目录
什么是自动装配
何时自动装配
原理分析
注:以下展示的代码springboot的版本为2.0.3版。因源码过长,大家选择展开代码 ㄟ( ▔, ▔ )ㄏ
什么是自动装配
自动装配还是利用了SpringFactoriesLoader来加载META-INF/spring.factoires文件里所有配置的EnableAutoConfgruation,它会经过exclude和filter等操作,最终确定要装配的类
流程:@Configuration 配置的Bean -> BeanFactory -> ImportSelector -> AutoConfigurationSelectImporter ->
SpringFactoriesLoader -> META-INF/spring.factories->
所有配置的@EnableAutoConfiguration -> @Configuration -> 收集好后注册到IOC容器里
何时自动装配,过程是什么
处理@Configuration的核心还是ConfigurationClassPostProcessor,这个类实现了BeanFactoryPostProcessor, 因此当AbstractApplicationContext执行refresh方法里的invokeBeanFactoryPostProcessors(beanFactory)方法时会执行自动装配
通过:ConfigurationClassPostProcessor这个类中的 ConfigurationClassParser parser()方法
过程:refresh() -> 注册BeanFatoryPostProcessor -> ConfigurationClassParser-> 内部类DeferredImportSelectorHolder
-> DeferredImportSeletor -> AutoConfigurationImportSelector -> selectImports方法
原理分析
什么是自动装配?
@EnableAutoConfiguration源码里import了EnableAutoConfigurationImportSelector这个类,
EnableAutoConfiguration接口
/* * Copyright 2012-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.boot.autoconfigure; import java.lang.annotation.Documented; import java.lang.annotation.ElementType; import java.lang.annotation.Inherited; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; import org.springframework.boot.autoconfigure.condition.ConditionalOnBean; import org.springframework.boot.autoconfigure.condition.ConditionalOnClass; import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean; import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory; import org.springframework.boot.web.servlet.server.ServletWebServerFactory; import org.springframework.context.annotation.Conditional; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.Import; import org.springframework.core.io.support.SpringFactoriesLoader; /** * Enable auto-configuration of the Spring Application Context, attempting to guess and * configure beans that you are likely to need. Auto-configuration classes are usually * applied based on your classpath and what beans you have defined. For example, if you * have {@code tomcat-embedded.jar} on your classpath you are likely to want a * {@link TomcatServletWebServerFactory} (unless you have defined your own * {@link ServletWebServerFactory} bean). * <p> * When using {@link SpringBootApplication}, the auto-configuration of the context is * automatically enabled and adding this annotation has therefore no additional effect. * <p> * Auto-configuration tries to be as intelligent as possible and will back-away as you * define more of your own configuration. You can always manually {@link #exclude()} any * configuration that you never want to apply (use {@link #excludeName()} if you don‘t * have access to them). You can also exclude them via the * {@code spring.autoconfigure.exclude} property. Auto-configuration is always applied * after user-defined beans have been registered. * <p> * The package of the class that is annotated with {@code @EnableAutoConfiguration}, * usually via {@code @SpringBootApplication}, has specific significance and is often used * as a ‘default‘. For example, it will be used when scanning for {@code @Entity} classes. * It is generally recommended that you place {@code @EnableAutoConfiguration} (if you‘re * not using {@code @SpringBootApplication}) in a root package so that all sub-packages * and classes can be searched. * <p> * Auto-configuration classes are regular Spring {@link Configuration} beans. They are * located using the {@link SpringFactoriesLoader} mechanism (keyed against this class). * Generally auto-configuration beans are {@link Conditional @Conditional} beans (most * often using {@link ConditionalOnClass @ConditionalOnClass} and * {@link ConditionalOnMissingBean @ConditionalOnMissingBean} annotations). * * @author Phillip Webb * @author Stephane Nicoll * @see ConditionalOnBean * @see ConditionalOnMissingBean * @see ConditionalOnClass * @see AutoConfigureAfter * @see SpringBootApplication */ @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Inherited @AutoConfigurationPackage @Import(AutoConfigurationImportSelector.class) public @interface EnableAutoConfiguration { String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration"; /** * Exclude specific auto-configuration classes such that they will never be applied. * @return the classes to exclude */ Class<?>[] exclude() default {}; /** * Exclude specific auto-configuration class names such that they will never be * applied. * @return the class names to exclude * @since 1.3.0 */ String[] excludeName() default {}; }
但是该类在SpringBoot1.5.X版本已经过时了,因此我们看一下它的父类AutoConfigurationImportSelector。(2.0.3版直接引入了父类AutoConfigurationImportSelector)
AutoConfigurationImportSelector类
/* * Copyright 2012-2018 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.boot.autoconfigure; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.LinkedHashMap; import java.util.LinkedHashSet; import java.util.List; import java.util.Map; import java.util.Set; import java.util.concurrent.TimeUnit; import java.util.stream.Collectors; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.BeansException; import org.springframework.beans.factory.Aware; import org.springframework.beans.factory.BeanClassLoaderAware; import org.springframework.beans.factory.BeanFactory; import org.springframework.beans.factory.BeanFactoryAware; import org.springframework.beans.factory.NoSuchBeanDefinitionException; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.boot.context.properties.bind.Binder; import org.springframework.context.EnvironmentAware; import org.springframework.context.ResourceLoaderAware; import org.springframework.context.annotation.DeferredImportSelector; import org.springframework.core.Ordered; import org.springframework.core.annotation.AnnotationAttributes; import org.springframework.core.env.ConfigurableEnvironment; import org.springframework.core.env.Environment; import org.springframework.core.io.ResourceLoader; import org.springframework.core.io.support.SpringFactoriesLoader; import org.springframework.core.type.AnnotationMetadata; import org.springframework.core.type.classreading.CachingMetadataReaderFactory; import org.springframework.core.type.classreading.MetadataReaderFactory; import org.springframework.util.Assert; import org.springframework.util.ClassUtils; import org.springframework.util.StringUtils; /** * {@link DeferredImportSelector} to handle {@link EnableAutoConfiguration * auto-configuration}. This class can also be subclassed if a custom variant of * {@link EnableAutoConfiguration @EnableAutoConfiguration}. is needed. * * @author Phillip Webb * @author Andy Wilkinson * @author Stephane Nicoll * @author Madhura Bhave * @since 1.3.0 * @see EnableAutoConfiguration */ public class AutoConfigurationImportSelector implements DeferredImportSelector, BeanClassLoaderAware, ResourceLoaderAware, BeanFactoryAware, EnvironmentAware, Ordered { private static final String[] NO_IMPORTS = {}; private static final Log logger = LogFactory .getLog(AutoConfigurationImportSelector.class); private static final String PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE = "spring.autoconfigure.exclude"; private ConfigurableListableBeanFactory beanFactory; private Environment environment; private ClassLoader beanClassLoader; private ResourceLoader resourceLoader; @Override public String[] selectImports(AnnotationMetadata annotationMetadata) { if (!isEnabled(annotationMetadata)) { return NO_IMPORTS; } AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader .loadMetadata(this.beanClassLoader); AnnotationAttributes attributes = getAttributes(annotationMetadata); List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes); configurations = removeDuplicates(configurations); Set<String> exclusions = getExclusions(annotationMetadata, attributes); checkExcludedClasses(configurations, exclusions); configurations.removeAll(exclusions); configurations = filter(configurations, autoConfigurationMetadata); fireAutoConfigurationImportEvents(configurations, exclusions); return StringUtils.toStringArray(configurations); } @Override public Class<? extends Group> getImportGroup() { return AutoConfigurationGroup.class; } protected boolean isEnabled(AnnotationMetadata metadata) { if (getClass() == AutoConfigurationImportSelector.class) { return getEnvironment().getProperty( EnableAutoConfiguration.ENABLED_OVERRIDE_PROPERTY, Boolean.class, true); } return true; } /** * Return the appropriate {@link AnnotationAttributes} from the * {@link AnnotationMetadata}. By default this method will return attributes for * {@link #getAnnotationClass()}. * @param metadata the annotation metadata * @return annotation attributes */ protected AnnotationAttributes getAttributes(AnnotationMetadata metadata) { String name = getAnnotationClass().getName(); AnnotationAttributes attributes = AnnotationAttributes .fromMap(metadata.getAnnotationAttributes(name, true)); Assert.notNull(attributes, () -> "No auto-configuration attributes found. Is " + metadata.getClassName() + " annotated with " + ClassUtils.getShortName(name) + "?"); return attributes; } /** * Return the source annotation class used by the selector. * @return the annotation class */ protected Class<?> getAnnotationClass() { return EnableAutoConfiguration.class; } /** * Return the auto-configuration class names that should be considered. By default * this method will load candidates using {@link SpringFactoriesLoader} with * {@link #getSpringFactoriesLoaderFactoryClass()}. * @param metadata the source metadata * @param attributes the {@link #getAttributes(AnnotationMetadata) annotation * attributes} * @return a list of candidate configurations */ protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) { List<String> configurations = SpringFactoriesLoader.loadFactoryNames( getSpringFactoriesLoaderFactoryClass(), getBeanClassLoader()); Assert.notEmpty(configurations, "No auto configuration classes found in META-INF/spring.factories. If you " + "are using a custom packaging, make sure that file is correct."); return configurations; } /** * Return the class used by {@link SpringFactoriesLoader} to load configuration * candidates. * @return the factory class */ protected Class<?> getSpringFactoriesLoaderFactoryClass() { return EnableAutoConfiguration.class; } private void checkExcludedClasses(List<String> configurations, Set<String> exclusions) { List<String> invalidExcludes = new ArrayList<>(exclusions.size()); for (String exclusion : exclusions) { if (ClassUtils.isPresent(exclusion, getClass().getClassLoader()) && !configurations.contains(exclusion)) { invalidExcludes.add(exclusion); } } if (!invalidExcludes.isEmpty()) { handleInvalidExcludes(invalidExcludes); } } /** * Handle any invalid excludes that have been specified. * @param invalidExcludes the list of invalid excludes (will always have at least one * element) */ protected void handleInvalidExcludes(List<String> invalidExcludes) { StringBuilder message = new StringBuilder(); for (String exclude : invalidExcludes) { message.append("\t- ").append(exclude).append(String.format("%n")); } throw new IllegalStateException(String .format("The following classes could not be excluded because they are" + " not auto-configuration classes:%n%s", message)); } /** * Return any exclusions that limit the candidate configurations. * @param metadata the source metadata * @param attributes the {@link #getAttributes(AnnotationMetadata) annotation * attributes} * @return exclusions or an empty set */ protected Set<String> getExclusions(AnnotationMetadata metadata, AnnotationAttributes attributes) { Set<String> excluded = new LinkedHashSet<>(); excluded.addAll(asList(attributes, "exclude")); excluded.addAll(Arrays.asList(attributes.getStringArray("excludeName"))); excluded.addAll(getExcludeAutoConfigurationsProperty()); return excluded; } private List<String> getExcludeAutoConfigurationsProperty() { if (getEnvironment() instanceof ConfigurableEnvironment) { Binder binder = Binder.get(getEnvironment()); return binder.bind(PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE, String[].class) .map(Arrays::asList).orElse(Collections.emptyList()); } String[] excludes = getEnvironment() .getProperty(PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE, String[].class); return (excludes != null ? Arrays.asList(excludes) : Collections.emptyList()); } private List<String> filter(List<String> configurations, AutoConfigurationMetadata autoConfigurationMetadata) { long startTime = System.nanoTime(); String[] candidates = StringUtils.toStringArray(configurations); boolean[] skip = new boolean[candidates.length]; boolean skipped = false; for (AutoConfigurationImportFilter filter : getAutoConfigurationImportFilters()) { invokeAwareMethods(filter); boolean[] match = filter.match(candidates, autoConfigurationMetadata); for (int i = 0; i < match.length; i++) { if (!match[i]) { skip[i] = true; skipped = true; } } } if (!skipped) { return configurations; } List<String> result = new ArrayList<>(candidates.length); for (int i = 0; i < candidates.length; i++) { if (!skip[i]) { result.add(candidates[i]); } } if (logger.isTraceEnabled()) { int numberFiltered = configurations.size() - result.size(); logger.trace("Filtered " + numberFiltered + " auto configuration class in " + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime) + " ms"); } return new ArrayList<>(result); } protected List<AutoConfigurationImportFilter> getAutoConfigurationImportFilters() { return SpringFactoriesLoader.loadFactories(AutoConfigurationImportFilter.class, this.beanClassLoader); } protected final <T> List<T> removeDuplicates(List<T> list) { return new ArrayList<>(new LinkedHashSet<>(list)); } protected final List<String> asList(AnnotationAttributes attributes, String name) { String[] value = attributes.getStringArray(name); return Arrays.asList(value != null ? value : new String[0]); } private void fireAutoConfigurationImportEvents(List<String> configurations, Set<String> exclusions) { List<AutoConfigurationImportListener> listeners = getAutoConfigurationImportListeners(); if (!listeners.isEmpty()) { AutoConfigurationImportEvent event = new AutoConfigurationImportEvent(this, configurations, exclusions); for (AutoConfigurationImportListener listener : listeners) { invokeAwareMethods(listener); listener.onAutoConfigurationImportEvent(event); } } } protected List<AutoConfigurationImportListener> getAutoConfigurationImportListeners() { return SpringFactoriesLoader.loadFactories(AutoConfigurationImportListener.class, this.beanClassLoader); } private void invokeAwareMethods(Object instance) { if (instance instanceof Aware) { if (instance instanceof BeanClassLoaderAware) { ((BeanClassLoaderAware) instance) .setBeanClassLoader(this.beanClassLoader); } if (instance instanceof BeanFactoryAware) { ((BeanFactoryAware) instance).setBeanFactory(this.beanFactory); } if (instance instanceof EnvironmentAware) { ((EnvironmentAware) instance).setEnvironment(this.environment); } if (instance instanceof ResourceLoaderAware) { ((ResourceLoaderAware) instance).setResourceLoader(this.resourceLoader); } } } @Override public void setBeanFactory(BeanFactory beanFactory) throws BeansException { Assert.isInstanceOf(ConfigurableListableBeanFactory.class, beanFactory); this.beanFactory = (ConfigurableListableBeanFactory) beanFactory; } protected final ConfigurableListableBeanFactory getBeanFactory() { return this.beanFactory; } @Override public void setBeanClassLoader(ClassLoader classLoader) { this.beanClassLoader = classLoader; } protected ClassLoader getBeanClassLoader() { return this.beanClassLoader; } @Override public void setEnvironment(Environment environment) { this.environment = environment; } protected final Environment getEnvironment() { return this.environment; } @Override public void setResourceLoader(ResourceLoader resourceLoader) { this.resourceLoader = resourceLoader; } protected final ResourceLoader getResourceLoader() { return this.resourceLoader; } @Override public int getOrder() { return Ordered.LOWEST_PRECEDENCE - 1; } private static class AutoConfigurationGroup implements DeferredImportSelector.Group, BeanClassLoaderAware, BeanFactoryAware, ResourceLoaderAware { private ClassLoader beanClassLoader; private BeanFactory beanFactory; private ResourceLoader resourceLoader; private final Map<String, AnnotationMetadata> entries = new LinkedHashMap<>(); @Override public void setBeanClassLoader(ClassLoader classLoader) { this.beanClassLoader = classLoader; } @Override public void setBeanFactory(BeanFactory beanFactory) { this.beanFactory = beanFactory; } @Override public void setResourceLoader(ResourceLoader resourceLoader) { this.resourceLoader = resourceLoader; } @Override public void process(AnnotationMetadata annotationMetadata, DeferredImportSelector deferredImportSelector) { String[] imports = deferredImportSelector.selectImports(annotationMetadata); for (String importClassName : imports) { this.entries.put(importClassName, annotationMetadata); } } @Override public Iterable<Entry> selectImports() { return sortAutoConfigurations().stream() .map((importClassName) -> new Entry(this.entries.get(importClassName), importClassName)) .collect(Collectors.toList()); } private List<String> sortAutoConfigurations() { List<String> autoConfigurations = new ArrayList<>(this.entries.keySet()); if (this.entries.size() <= 1) { return autoConfigurations; } AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader .loadMetadata(this.beanClassLoader); return new AutoConfigurationSorter(getMetadataReaderFactory(), autoConfigurationMetadata).getInPriorityOrder(autoConfigurations); } private MetadataReaderFactory getMetadataReaderFactory() { try { return this.beanFactory.getBean( SharedMetadataReaderFactoryContextInitializer.BEAN_NAME, MetadataReaderFactory.class); } catch (NoSuchBeanDefinitionException ex) { return new CachingMetadataReaderFactory(this.resourceLoader); } } } }
该类实现了DeferredImportSelector接口,这个接口继承了ImportSelector。该接口主要是为了导入@Configuration的配置项。
DeferredImportSelector接口
/* * Copyright 2002-2018 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.context.annotation; import java.util.Objects; import org.springframework.core.type.AnnotationMetadata; import org.springframework.lang.Nullable; /** * A variation of {@link ImportSelector} that runs after all {@code @Configuration} beans * have been processed. This type of selector can be particularly useful when the selected * imports are {@code @Conditional}. * * <p>Implementations can also extend the {@link org.springframework.core.Ordered} * interface or use the {@link org.springframework.core.annotation.Order} annotation to * indicate a precedence against other {@link DeferredImportSelector}s. * * <p>Implementations may also provide an {@link #getImportGroup() import group} which * can provide additional sorting and filtering logic across different selectors. * * @author Phillip Webb * @author Stephane Nicoll * @since 4.0 */ public interface DeferredImportSelector extends ImportSelector { /** * Return a specific import group or {@code null} if no grouping is required. * @return the import group class or {@code null} */ @Nullable default Class<? extends Group> getImportGroup() { return null; } /** * Interface used to group results from different import selectors. */ interface Group { /** * Process the {@link AnnotationMetadata} of the importing @{@link Configuration} * class using the specified {@link DeferredImportSelector}. */ void process(AnnotationMetadata metadata, DeferredImportSelector selector); /** * Return the {@link Entry entries} of which class(es) should be imported for this * group. */ Iterable<Entry> selectImports(); /** * An entry that holds the {@link AnnotationMetadata} of the importing * {@link Configuration} class and the class name to import. */ class Entry { private final AnnotationMetadata metadata; private final String importClassName; public Entry(AnnotationMetadata metadata, String importClassName) { this.metadata = metadata; this.importClassName = importClassName; } /** * Return the {@link AnnotationMetadata} of the importing * {@link Configuration} class. */ public AnnotationMetadata getMetadata() { return this.metadata; } /** * Return the fully qualified name of the class to import. */ public String getImportClassName() { return this.importClassName; } @Override public boolean equals(Object o) { if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } Entry entry = (Entry) o; return Objects.equals(this.metadata, entry.metadata) && Objects.equals(this.importClassName, entry.importClassName); } @Override public int hashCode() { return Objects.hash(this.metadata, this.importClassName); } } } }
ImportSelector接口
/* * Copyright 2002-2013 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.context.annotation; import org.springframework.core.type.AnnotationMetadata; /** * Interface to be implemented by types that determine which @{@link Configuration} * class(es) should be imported based on a given selection criteria, usually one or more * annotation attributes. * * <p>An {@link ImportSelector} may implement any of the following * {@link org.springframework.beans.factory.Aware Aware} interfaces, and their respective * methods will be called prior to {@link #selectImports}: * <ul> * <li>{@link org.springframework.context.EnvironmentAware EnvironmentAware}</li> * <li>{@link org.springframework.beans.factory.BeanFactoryAware BeanFactoryAware}</li> * <li>{@link org.springframework.beans.factory.BeanClassLoaderAware BeanClassLoaderAware}</li> * <li>{@link org.springframework.context.ResourceLoaderAware ResourceLoaderAware}</li> * </ul> * * <p>ImportSelectors are usually processed in the same way as regular {@code @Import} * annotations, however, it is also possible to defer selection of imports until all * {@code @Configuration} classes have been processed (see {@link DeferredImportSelector} * for details). * * @author Chris Beams * @since 3.1 * @see DeferredImportSelector * @see Import * @see ImportBeanDefinitionRegistrar * @see Configuration */ public interface ImportSelector { /** * Select and return the names of which class(es) should be imported based on * the {@link AnnotationMetadata} of the importing @{@link Configuration} class. */ String[] selectImports(AnnotationMetadata importingClassMetadata); }
然后我们回头看AutoConfigurationImportSelector重写的selectImport方法,该方法刚开始会先判断是否进行自动装配,而后会从META-INF/spring-autoconfigure-metadata.properties读取元数据与元数据的相关属性
@Override public String[] selectImports(AnnotationMetadata annotationMetadata) { if (!isEnabled(annotationMetadata)) { return NO_IMPORTS; } AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader .loadMetadata(this.beanClassLoader); AnnotationAttributes attributes = getAttributes(annotationMetadata); List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes); configurations = removeDuplicates(configurations); Set<String> exclusions = getExclusions(annotationMetadata, attributes); checkExcludedClasses(configurations, exclusions); configurations.removeAll(exclusions); configurations = filter(configurations, autoConfigurationMetadata); fireAutoConfigurationImportEvents(configurations, exclusions); return StringUtils.toStringArray(configurations); }
紧接着会调用getCandidateConfigurations方法。这个方法里有个 SpringFactoryiesLoader, 它会读取META-INF/spring.factories下的EnableAutoConfiguration的配置
/** * Return the auto-configuration class names that should be considered. By default * this method will load candidates using {@link SpringFactoriesLoader} with * {@link #getSpringFactoriesLoaderFactoryClass()}. * @param metadata the source metadata * @param attributes the {@link #getAttributes(AnnotationMetadata) annotation * attributes} * @return a list of candidate configurations */ protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) { List<String> configurations = SpringFactoriesLoader.loadFactoryNames( getSpringFactoriesLoaderFactoryClass(), getBeanClassLoader()); Assert.notEmpty(configurations, "No auto configuration classes found in META-INF/spring.factories. If you " + "are using a custom packaging, make sure that file is correct."); return configurations; } /** * Return the class used by {@link SpringFactoriesLoader} to load configuration * candidates. * @return the factory class */ protected Class<?> getSpringFactoriesLoaderFactoryClass() { return EnableAutoConfiguration.class; }
紧接着在进行排除与过滤,进而得到需要装配的类。最后让所有配置在META-INF/spring.factories下的AutoConfigurationImportListener执行AutoConfigurationImportEvent事件
所有配置的@EnableAutoConfiguration 收集好后注册到IOC容器里
private void fireAutoConfigurationImportEvents(List<String> configurations, Set<String> exclusions) { List<AutoConfigurationImportListener> listeners = getAutoConfigurationImportListeners(); if (!listeners.isEmpty()) { AutoConfigurationImportEvent event = new AutoConfigurationImportEvent(this, configurations, exclusions); for (AutoConfigurationImportListener listener : listeners) { invokeAwareMethods(listener); listener.onAutoConfigurationImportEvent(event); } } } protected List<AutoConfigurationImportListener> getAutoConfigurationImportListeners() { return SpringFactoriesLoader.loadFactories(AutoConfigurationImportListener.class, this.beanClassLoader); }
何时自动装配?
上面只是确定最终要将哪些类进行自动装配,那么SpringBoot何时处理这些自动装配的类呢?下面我们简要的分析一下:
AbstractApplicationContext的refresh方法:
当AbstractApplicationContext执行refresh方法里的invokeBeanFactoryPostProcessors(beanFactory)方法时会执行自动装配
AbstractApplicationContext类的refresh()方法
@Override public void refresh() throws BeansException, IllegalStateException { synchronized (this.startupShutdownMonitor) { // Prepare this context for refreshing. prepareRefresh(); // Tell the subclass to refresh the internal bean factory. ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); // Prepare the bean factory for use in this context. prepareBeanFactory(beanFactory); try { // Allows post-processing of the bean factory in context subclasses. postProcessBeanFactory(beanFactory); // Invoke factory processors registered as beans in the context. invokeBeanFactoryPostProcessors(beanFactory); // Register bean processors that intercept bean creation. registerBeanPostProcessors(beanFactory); // Initialize message source for this context. initMessageSource(); // Initialize event multicaster for this context. initApplicationEventMulticaster(); // Initialize other special beans in specific context subclasses. onRefresh(); // Check for listener beans and register them. registerListeners(); // Instantiate all remaining (non-lazy-init) singletons. finishBeanFactoryInitialization(beanFactory); // Last step: publish corresponding event. finishRefresh(); } catch (BeansException ex) { if (logger.isWarnEnabled()) { logger.warn("Exception encountered during context initialization - " + "cancelling refresh attempt: " + ex); } // Destroy already created singletons to avoid dangling resources. destroyBeans(); // Reset ‘active‘ flag. cancelRefresh(ex); // Propagate exception to caller. throw ex; } finally { // Reset common introspection caches in Spring‘s core, since we // might not ever need metadata for singleton beans anymore... resetCommonCaches(); } } }
在这里是处理BeanFactoryPostProcessor的,那么我们在来看一下这个接口BeanDefinitionRegistryPostProcessor
BeanDefinitionRegistryPostProcessor接口
/* * Copyright 2002-2010 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.beans.factory.support; import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanFactoryPostProcessor; /** * Extension to the standard {@link BeanFactoryPostProcessor} SPI, allowing for * the registration of further bean definitions <i>before</i> regular * BeanFactoryPostProcessor detection kicks in. In particular, * BeanDefinitionRegistryPostProcessor may register further bean definitions * which in turn define BeanFactoryPostProcessor instances. * * @author Juergen Hoeller * @since 3.0.1 * @see org.springframework.context.annotation.ConfigurationClassPostProcessor */ public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor { /** * Modify the application context‘s internal bean definition registry after its * standard initialization. All regular bean definitions will have been loaded, * but no beans will have been instantiated yet. This allows for adding further * bean definitions before the next post-processing phase kicks in. * @param registry the bean definition registry used by the application context * @throws org.springframework.beans.BeansException in case of errors */ void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException; }
该类又实现 BeanFactoryPostProcessor
BeanFactoryPostProcessor接口
/* * Copyright 2002-2016 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.beans.factory.config; import org.springframework.beans.BeansException; /** * Allows for custom modification of an application context‘s bean definitions, * adapting the bean property values of the context‘s underlying bean factory. * * <p>Application contexts can auto-detect BeanFactoryPostProcessor beans in * their bean definitions and apply them before any other beans get created. * * <p>Useful for custom config files targeted at system administrators that * override bean properties configured in the application context. * * <p>See PropertyResourceConfigurer and its concrete implementations * for out-of-the-box solutions that address such configuration needs. * * <p>A BeanFactoryPostProcessor may interact with and modify bean * definitions, but never bean instances. Doing so may cause premature bean * instantiation, violating the container and causing unintended side-effects. * If bean instance interaction is required, consider implementing * {@link BeanPostProcessor} instead. * * @author Juergen Hoeller * @since 06.07.2003 * @see BeanPostProcessor * @see PropertyResourceConfigurer */ @FunctionalInterface public interface BeanFactoryPostProcessor { /** * Modify the application context‘s internal bean factory after its standard * initialization. All bean definitions will have been loaded, but no beans * will have been instantiated yet. This allows for overriding or adding * properties even to eager-initializing beans. * @param beanFactory the bean factory used by the application context * @throws org.springframework.beans.BeansException in case of errors */ void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException; }
ConfigurationClassPostProcessor 类
处理@Configuration的核心还是ConfigurationClassPostProcessor。该类主要处理@Configuration注解的,它实现了BeanDefinitionRegistryPostProcessor, 那么也间接实现了BeanFactoryPostProcessor,代码如下:
ConfigurationClassPostProcessor类
/* * Copyright 2002-2018 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.context.annotation; import java.beans.PropertyDescriptor; import java.util.ArrayList; import java.util.Arrays; import java.util.HashSet; import java.util.LinkedHashMap; import java.util.LinkedHashSet; import java.util.List; import java.util.Map; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.aop.framework.autoproxy.AutoProxyUtils; import org.springframework.beans.PropertyValues; import org.springframework.beans.factory.BeanClassLoaderAware; import org.springframework.beans.factory.BeanDefinitionStoreException; import org.springframework.beans.factory.BeanFactory; import org.springframework.beans.factory.config.BeanDefinition; import org.springframework.beans.factory.config.BeanDefinitionHolder; import org.springframework.beans.factory.config.BeanFactoryPostProcessor; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter; import org.springframework.beans.factory.config.SingletonBeanRegistry; import org.springframework.beans.factory.parsing.FailFastProblemReporter; import org.springframework.beans.factory.parsing.PassThroughSourceExtractor; import org.springframework.beans.factory.parsing.ProblemReporter; import org.springframework.beans.factory.parsing.SourceExtractor; import org.springframework.beans.factory.support.AbstractBeanDefinition; import org.springframework.beans.factory.support.BeanDefinitionRegistry; import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor; import org.springframework.beans.factory.support.BeanNameGenerator; import org.springframework.context.EnvironmentAware; import org.springframework.context.ResourceLoaderAware; import org.springframework.context.annotation.ConfigurationClassEnhancer.EnhancedConfiguration; import org.springframework.core.Ordered; import org.springframework.core.PriorityOrdered; import org.springframework.core.env.Environment; import org.springframework.core.env.StandardEnvironment; import org.springframework.core.io.DefaultResourceLoader; import org.springframework.core.io.ResourceLoader; import org.springframework.core.type.AnnotationMetadata; import org.springframework.core.type.classreading.CachingMetadataReaderFactory; import org.springframework.core.type.classreading.MetadataReaderFactory; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.util.ClassUtils; import static org.springframework.context.annotation.AnnotationConfigUtils.*; /** * {@link BeanFactoryPostProcessor} used for bootstrapping processing of * {@link Configuration @Configuration} classes. * * <p>Registered by default when using {@code <context:annotation-config/>} or * {@code <context:component-scan/>}. Otherwise, may be declared manually as * with any other BeanFactoryPostProcessor. * * <p>This post processor is {@link Ordered#HIGHEST_PRECEDENCE} as it is important * that any {@link Bean} methods declared in Configuration classes have their * respective bean definitions registered before any other BeanFactoryPostProcessor * executes. * * @author Chris Beams * @author Juergen Hoeller * @author Phillip Webb * @since 3.0 */ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPostProcessor, PriorityOrdered, ResourceLoaderAware, BeanClassLoaderAware, EnvironmentAware { private static final String IMPORT_REGISTRY_BEAN_NAME = ConfigurationClassPostProcessor.class.getName() + ".importRegistry"; private final Log logger = LogFactory.getLog(getClass()); private SourceExtractor sourceExtractor = new PassThroughSourceExtractor(); private ProblemReporter problemReporter = new FailFastProblemReporter(); @Nullable private Environment environment; private ResourceLoader resourceLoader = new DefaultResourceLoader(); @Nullable private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader(); private MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory(); private boolean setMetadataReaderFactoryCalled = false; private final Set<Integer> registriesPostProcessed = new HashSet<>(); private final Set<Integer> factoriesPostProcessed = new HashSet<>(); @Nullable private ConfigurationClassBeanDefinitionReader reader; private boolean localBeanNameGeneratorSet = false; /* Using short class names as default bean names */ private BeanNameGenerator componentScanBeanNameGenerator = new AnnotationBeanNameGenerator(); /* Using fully qualified class names as default bean names */ private BeanNameGenerator importBeanNameGenerator = new AnnotationBeanNameGenerator() { @Override protected String buildDefaultBeanName(BeanDefinition definition) { String beanClassName = definition.getBeanClassName(); Assert.state(beanClassName != null, "No bean class name set"); return beanClassName; } }; @Override public int getOrder() { return Ordered.LOWEST_PRECEDENCE; // within PriorityOrdered } /** * Set the {@link SourceExtractor} to use for generated bean definitions * that correspond to {@link Bean} factory methods. */ public void setSourceExtractor(@Nullable SourceExtractor sourceExtractor) { this.sourceExtractor = (sourceExtractor != null ? sourceExtractor : new PassThroughSourceExtractor()); } /** * Set the {@link ProblemReporter} to use. * <p>Used to register any problems detected with {@link Configuration} or {@link Bean} * declarations. For instance, an @Bean method marked as {@code final} is illegal * and would be reported as a problem. Defaults to {@link FailFastProblemReporter}. */ public void setProblemReporter(@Nullable ProblemReporter problemReporter) { this.problemReporter = (problemReporter != null ? problemReporter : new FailFastProblemReporter()); } /** * Set the {@link MetadataReaderFactory} to use. * <p>Default is a {@link CachingMetadataReaderFactory} for the specified * {@linkplain #setBeanClassLoader bean class loader}. */ public void setMetadataReaderFactory(MetadataReaderFactory metadataReaderFactory) { Assert.notNull(metadataReaderFactory, "MetadataReaderFactory must not be null"); this.metadataReaderFactory = metadataReaderFactory; this.setMetadataReaderFactoryCalled = true; } /** * Set the {@link BeanNameGenerator} to be used when triggering component scanning * from {@link Configuration} classes and when registering {@link Import}‘ed * configuration classes. The default is a standard {@link AnnotationBeanNameGenerator} * for scanned components (compatible with the default in {@link ClassPathBeanDefinitionScanner}) * and a variant thereof for imported configuration classes (using unique fully-qualified * class names instead of standard component overriding). * <p>Note that this strategy does <em>not</em> apply to {@link Bean} methods. * <p>This setter is typically only appropriate when configuring the post-processor as * a standalone bean definition in XML, e.g. not using the dedicated * {@code AnnotationConfig*} application contexts or the {@code * <context:annotation-config>} element. Any bean name generator specified against * the application context will take precedence over any value set here. * @since 3.1.1 * @see AnnotationConfigApplicationContext#setBeanNameGenerator(BeanNameGenerator) * @see AnnotationConfigUtils#CONFIGURATION_BEAN_NAME_GENERATOR */ public void setBeanNameGenerator(BeanNameGenerator beanNameGenerator) { Assert.notNull(beanNameGenerator, "BeanNameGenerator must not be null"); this.localBeanNameGeneratorSet = true; this.componentScanBeanNameGenerator = beanNameGenerator; this.importBeanNameGenerator = beanNameGenerator; } @Override public void setEnvironment(Environment environment) { Assert.notNull(environment, "Environment must not be null"); this.environment = environment; } @Override public void setResourceLoader(ResourceLoader resourceLoader) { Assert.notNull(resourceLoader, "ResourceLoader must not be null"); this.resourceLoader = resourceLoader; if (!this.setMetadataReaderFactoryCalled) { this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader); } } @Override public void setBeanClassLoader(ClassLoader beanClassLoader) { this.beanClassLoader = beanClassLoader; if (!this.setMetadataReaderFactoryCalled) { this.metadataReaderFactory = new CachingMetadataReaderFactory(beanClassLoader); } } /** * Derive further bean definitions from the configuration classes in the registry. */ @Override public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) { int registryId = System.identityHashCode(registry); if (this.registriesPostProcessed.contains(registryId)) { throw new IllegalStateException( "postProcessBeanDefinitionRegistry already called on this post-processor against " + registry); } if (this.factoriesPostProcessed.contains(registryId)) { throw new IllegalStateException( "postProcessBeanFactory already called on this post-processor against " + registry); } this.registriesPostProcessed.add(registryId); processConfigBeanDefinitions(registry); } /** * Prepare the Configuration classes for servicing bean requests at runtime * by replacing them with CGLIB-enhanced subclasses. */ @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { int factoryId = System.identityHashCode(beanFactory); if (this.factoriesPostProcessed.contains(factoryId)) { throw new IllegalStateException( "postProcessBeanFactory already called on this post-processor against " + beanFactory); } this.factoriesPostProcessed.add(factoryId); if (!this.registriesPostProcessed.contains(factoryId)) { // BeanDefinitionRegistryPostProcessor hook apparently not supported... // Simply call processConfigurationClasses lazily at this point then. processConfigBeanDefinitions((BeanDefinitionRegistry) beanFactory); } enhanceConfigurationClasses(beanFactory); beanFactory.addBeanPostProcessor(new ImportAwareBeanPostProcessor(beanFactory)); } /** * Build and validate a configuration model based on the registry of * {@link Configuration} classes. */ public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) { List<BeanDefinitionHolder> configCandidates = new ArrayList<>(); String[] candidateNames = registry.getBeanDefinitionNames(); for (String beanName : candidateNames) { BeanDefinition beanDef = registry.getBeanDefinition(beanName); if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) || ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) { if (logger.isDebugEnabled()) { logger.debug("Bean definition has already been processed as a configuration class: " + beanDef); } } else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) { configCandidates.add(new BeanDefinitionHolder(beanDef, beanName)); } } // Return immediately if no @Configuration classes were found if (configCandidates.isEmpty()) { return; } // Sort by previously determined @Order value, if applicable configCandidates.sort((bd1, bd2) -> { int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition()); int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition()); return Integer.compare(i1, i2); }); // Detect any custom bean name generation strategy supplied through the enclosing application context SingletonBeanRegistry sbr = null; if (registry instanceof SingletonBeanRegistry) { sbr = (SingletonBeanRegistry) registry; if (!this.localBeanNameGeneratorSet) { BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR); if (generator != null) { this.componentScanBeanNameGenerator = generator; this.importBeanNameGenerator = generator; } } } if (this.environment == null) { this.environment = new StandardEnvironment(); } // Parse each @Configuration class ConfigurationClassParser parser = new ConfigurationClassParser( this.metadataReaderFactory, this.problemReporter, this.environment, this.resourceLoader, this.componentScanBeanNameGenerator, registry); Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates); Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size()); do { parser.parse(candidates); parser.validate(); Set<ConfigurationClass> configClasses = new LinkedHashSet<>(parser.getConfigurationClasses()); configClasses.removeAll(alreadyParsed); // Read the model and create bean definitions based on its content if (this.reader == null) { this.reader = new ConfigurationClassBeanDefinitionReader( registry, this.sourceExtractor, this.resourceLoader, this.environment, this.importBeanNameGenerator, parser.getImportRegistry()); } this.reader.loadBeanDefinitions(configClasses); alreadyParsed.addAll(configClasses); candidates.clear(); if (registry.getBeanDefinitionCount() > candidateNames.length) { String[] newCandidateNames = registry.getBeanDefinitionNames(); Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames)); Set<String> alreadyParsedClasses = new HashSet<>(); for (ConfigurationClass configurationClass : alreadyParsed) { alreadyParsedClasses.add(configurationClass.getMetadata().getClassName()); } for (String candidateName : newCandidateNames) { if (!oldCandidateNames.contains(candidateName)) { BeanDefinition bd = registry.getBeanDefinition(candidateName); if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) && !alreadyParsedClasses.contains(bd.getBeanClassName())) { candidates.add(new BeanDefinitionHolder(bd, candidateName)); } } } candidateNames = newCandidateNames; } } while (!candidates.isEmpty()); // Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) { sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry()); } if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) { // Clear cache in externally provided MetadataReaderFactory; this is a no-op // for a shared cache since it‘ll be cleared by the ApplicationContext. ((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache(); } } /** * Post-processes a BeanFactory in search of Configuration class BeanDefinitions; * any candidates are then enhanced by a {@link ConfigurationClassEnhancer}. * Candidate status is determined by BeanDefinition attribute metadata. * @see ConfigurationClassEnhancer */ public void enhanceConfigurationClasses(ConfigurableListableBeanFactory beanFactory) { Map<String, AbstractBeanDefinition> configBeanDefs = new LinkedHashMap<>(); for (String beanName : beanFactory.getBeanDefinitionNames()) { BeanDefinition beanDef = beanFactory.getBeanDefinition(beanName); if (ConfigurationClassUtils.isFullConfigurationClass(beanDef)) { if (!(beanDef instanceof AbstractBeanDefinition)) { throw new BeanDefinitionStoreException("Cannot enhance @Configuration bean definition ‘" + beanName + "‘ since it is not stored in an AbstractBeanDefinition subclass"); } else if (logger.isWarnEnabled() && beanFactory.containsSingleton(beanName)) { logger.warn("Cannot enhance @Configuration bean definition ‘" + beanName + "‘ since its singleton instance has been created too early. The typical cause " + "is a non-static @Bean method with a BeanDefinitionRegistryPostProcessor " + "return type: Consider declaring such methods as ‘static‘."); } configBeanDefs.put(beanName, (AbstractBeanDefinition) beanDef); } } if (configBeanDefs.isEmpty()) { // nothing to enhance -> return immediately return; } ConfigurationClassEnhancer enhancer = new ConfigurationClassEnhancer(); for (Map.Entry<String, AbstractBeanDefinition> entry : configBeanDefs.entrySet()) { AbstractBeanDefinition beanDef = entry.getValue(); // If a @Configuration class gets proxied, always proxy the target class beanDef.setAttribute(AutoProxyUtils.PRESERVE_TARGET_CLASS_ATTRIBUTE, Boolean.TRUE); try { // Set enhanced subclass of the user-specified bean class Class<?> configClass = beanDef.resolveBeanClass(this.beanClassLoader); if (configClass != null) { Class<?> enhancedClass = enhancer.enhance(configClass, this.beanClassLoader); if (configClass != enhancedClass) { if (logger.isDebugEnabled()) { logger.debug(String.format("Replacing bean definition ‘%s‘ existing class ‘%s‘ with " + "enhanced class ‘%s‘", entry.getKey(), configClass.getName(), enhancedClass.getName())); } beanDef.setBeanClass(enhancedClass); } } } catch (Throwable ex) { throw new IllegalStateException("Cannot load configuration class: " + beanDef.getBeanClassName(), ex); } } } private static class ImportAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter { private final BeanFactory beanFactory; public ImportAwareBeanPostProcessor(BeanFactory beanFactory) { this.beanFactory = beanFactory; } @Override public PropertyValues postProcessPropertyValues( PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) { // Inject the BeanFactory before AutowiredAnnotationBeanPostProcessor‘s // postProcessPropertyValues method attempts to autowire other configuration beans. if (bean instanceof EnhancedConfiguration) { ((EnhancedConfiguration) bean).setBeanFactory(this.beanFactory); } return pvs; } @Override public Object postProcessBeforeInitialization(Object bean, String beanName) { if (bean instanceof ImportAware) { ImportRegistry ir = this.beanFactory.getBean(IMPORT_REGISTRY_BEAN_NAME, ImportRegistry.class); AnnotationMetadata importingClass = ir.getImportingClassFor(bean.getClass().getSuperclass().getName()); if (importingClass != null) { ((ImportAware) bean).setImportMetadata(importingClass); } } return bean; } } }
其关键代码为:postProcessBeanFactory和processConfigBeanDefinitions方法
这里可以看到解析每一个@ConfigurationClass的关键类是:ConfigurationClassParser 会调用该类的parse方法
ConfigurationClassParser类
/* * Copyright 2002-2018 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.context.annotation; import java.io.FileNotFoundException; import java.io.IOException; import java.lang.annotation.Annotation; import java.net.UnknownHostException; import java.util.ArrayDeque; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.Comparator; import java.util.Deque; import java.util.HashMap; import java.util.Iterator; import java.util.LinkedHashMap; import java.util.LinkedHashSet; import java.util.LinkedList; import java.util.List; import java.util.Map; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.BeanUtils; import org.springframework.beans.factory.BeanDefinitionStoreException; import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition; import org.springframework.beans.factory.config.BeanDefinition; import org.springframework.beans.factory.config.BeanDefinitionHolder; import org.springframework.beans.factory.parsing.Location; import org.springframework.beans.factory.parsing.Problem; import org.springframework.beans.factory.parsing.ProblemReporter; import org.springframework.beans.factory.support.AbstractBeanDefinition; import org.springframework.beans.factory.support.BeanDefinitionReader; import org.springframework.beans.factory.support.BeanDefinitionRegistry; import org.springframework.beans.factory.support.BeanNameGenerator; import org.springframework.context.annotation.ConfigurationCondition.ConfigurationPhase; import org.springframework.context.annotation.DeferredImportSelector.Group; import org.springframework.core.NestedIOException; import org.springframework.core.OrderComparator; import org.springframework.core.Ordered; import org.springframework.core.annotation.AnnotationAttributes; import org.springframework.core.annotation.AnnotationAwareOrderComparator; import org.springframework.core.annotation.AnnotationUtils; import org.springframework.core.env.CompositePropertySource; import org.springframework.core.env.ConfigurableEnvironment; import org.springframework.core.env.Environment; import org.springframework.core.env.MutablePropertySources; import org.springframework.core.env.PropertySource; import org.springframework.core.io.Resource; import org.springframework.core.io.ResourceLoader; import org.springframework.core.io.support.DefaultPropertySourceFactory; import org.springframework.core.io.support.EncodedResource; import org.springframework.core.io.support.PropertySourceFactory; import org.springframework.core.io.support.ResourcePropertySource; import org.springframework.core.type.AnnotationMetadata; import org.springframework.core.type.MethodMetadata; import org.springframework.core.type.StandardAnnotationMetadata; import org.springframework.core.type.classreading.MetadataReader; import org.springframework.core.type.classreading.MetadataReaderFactory; import org.springframework.core.type.filter.AssignableTypeFilter; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.util.ClassUtils; import org.springframework.util.CollectionUtils; import org.springframework.util.LinkedMultiValueMap; import org.springframework.util.MultiValueMap; import org.springframework.util.StringUtils; /** * Parses a {@link Configuration} class definition, populating a collection of * {@link ConfigurationClass} objects (parsing a single Configuration class may result in * any number of ConfigurationClass objects because one Configuration class may import * another using the {@link Import} annotation). * * <p>This class helps separate the concern of parsing the structure of a Configuration * class from the concern of registering BeanDefinition objects based on the * content of that model (with the exception of {@code @ComponentScan} annotations which * need to be registered immediately). * * <p>This ASM-based implementation avoids reflection and eager class loading in order to * interoperate effectively with lazy class loading in a Spring ApplicationContext. * * @author Chris Beams * @author Juergen Hoeller * @author Phillip Webb * @author Sam Brannen * @author Stephane Nicoll * @since 3.0 * @see ConfigurationClassBeanDefinitionReader */ class ConfigurationClassParser { private static final PropertySourceFactory DEFAULT_PROPERTY_SOURCE_FACTORY = new DefaultPropertySourceFactory(); private static final Comparator<DeferredImportSelectorHolder> DEFERRED_IMPORT_COMPARATOR = (o1, o2) -> AnnotationAwareOrderComparator.INSTANCE.compare(o1.getImportSelector(), o2.getImportSelector()); private final Log logger = LogFactory.getLog(getClass()); private final MetadataReaderFactory metadataReaderFactory; private final ProblemReporter problemReporter; private final Environment environment; private final ResourceLoader resourceLoader; private final BeanDefinitionRegistry registry; private final ComponentScanAnnotationParser componentScanParser; private final ConditionEvaluator conditionEvaluator; private final Map<ConfigurationClass, ConfigurationClass> configurationClasses = new LinkedHashMap<>(); private final Map<String, ConfigurationClass> knownSuperclasses = new HashMap<>(); private final List<String> propertySourceNames = new ArrayList<>(); private final ImportStack importStack = new ImportStack(); @Nullable private List<DeferredImportSelectorHolder> deferredImportSelectors; /** * Create a new {@link ConfigurationClassParser} instance that will be used * to populate the set of configuration classes. */ public ConfigurationClassParser(MetadataReaderFactory metadataReaderFactory, ProblemReporter problemReporter, Environment environment, ResourceLoader resourceLoader, BeanNameGenerator componentScanBeanNameGenerator, BeanDefinitionRegistry registry) { this.metadataReaderFactory = metadataReaderFactory; this.problemReporter = problemReporter; this.environment = environment; this.resourceLoader = resourceLoader; this.registry = registry; this.componentScanParser = new ComponentScanAnnotationParser( environment, resourceLoader, componentScanBeanNameGenerator, registry); this.conditionEvaluator = new ConditionEvaluator(registry, environment, resourceLoader); } public void parse(Set<BeanDefinitionHolder> configCandidates) { this.deferredImportSelectors = new LinkedList<>(); for (BeanDefinitionHolder holder : configCandidates) { BeanDefinition bd = holder.getBeanDefinition(); try { if (bd instanceof AnnotatedBeanDefinition) { parse(((AnnotatedBeanDefinition) bd).getMetadata(), holder.getBeanName()); } else if (bd instanceof AbstractBeanDefinition && ((AbstractBeanDefinition) bd).hasBeanClass()) { parse(((AbstractBeanDefinition) bd).getBeanClass(), holder.getBeanName()); } else { parse(bd.getBeanClassName(), holder.getBeanName()); } } catch (BeanDefinitionStoreException ex) { throw ex; } catch (Throwable ex) { throw new BeanDefinitionStoreException( "Failed to parse configuration class [" + bd.getBeanClassName() + "]", ex); } } processDeferredImportSelectors(); } protected final void parse(@Nullable String className, String beanName) throws IOException { Assert.notNull(className, "No bean class name for configuration class bean definition"); MetadataReader reader = this.metadataReaderFactory.getMetadataReader(className); processConfigurationClass(new ConfigurationClass(reader, beanName)); } protected final void parse(Class<?> clazz, String beanName) throws IOException { processConfigurationClass(new ConfigurationClass(clazz, beanName)); } protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException { processConfigurationClass(new ConfigurationClass(metadata, beanName)); } /** * Validate each {@link ConfigurationClass} object. * @see ConfigurationClass#validate */ public void validate() { for (ConfigurationClass configClass : this.configurationClasses.keySet()) { configClass.validate(this.problemReporter); } } public Set<ConfigurationClass> getConfigurationClasses() { return this.configurationClasses.keySet(); } protected void processConfigurationClass(ConfigurationClass configClass) throws IOException { if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) { return; } ConfigurationClass existingClass = this.configurationClasses.get(configClass); if (existingClass != null) { if (configClass.isImported()) { if (existingClass.isImported()) { existingClass.mergeImportedBy(configClass); } // Otherwise ignore new imported config class; existing non-imported class overrides it. return; } else { // Explicit bean definition found, probably replacing an import. // Let‘s remove the old one and go with the new one. this.configurationClasses.remove(configClass); this.knownSuperclasses.values().removeIf(configClass::equals); } } // Recursively process the configuration class and its superclass hierarchy. SourceClass sourceClass = asSourceClass(configClass); do { sourceClass = doProcessConfigurationClass(configClass, sourceClass); } while (sourceClass != null); this.configurationClasses.put(configClass, configClass); } /** * Apply processing and build a complete {@link ConfigurationClass} by reading the * annotations, members and methods from the source class. This method can be called * multiple times as relevant sources are discovered. * @param configClass the configuration class being build * @param sourceClass a source class * @return the superclass, or {@code null} if none found or previously processed */ @Nullable protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass) throws IOException { // Recursively process any member (nested) classes first processMemberClasses(configClass, sourceClass); // Process any @PropertySource annotations for (AnnotationAttributes propertySource : AnnotationConfigUtils.attributesForRepeatable( sourceClass.getMetadata(), PropertySources.class, org.springframework.context.annotation.PropertySource.class)) { if (this.environment instanceof ConfigurableEnvironment) { processPropertySource(propertySource); } else { logger.warn("Ignoring @PropertySource annotation on [" + sourceClass.getMetadata().getClassName() + "]. Reason: Environment must implement ConfigurableEnvironment"); } } // Process any @ComponentScan annotations Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable( sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class); if (!componentScans.isEmpty() && !this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) { for (AnnotationAttributes componentScan : componentScans) { // The config class is annotated with @ComponentScan -> perform the scan immediately Set<BeanDefinitionHolder> scannedBeanDefinitions = this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName()); // Check the set of scanned definitions for any further config classes and parse recursively if needed for (BeanDefinitionHolder holder : scannedBeanDefinitions) { BeanDefinition bdCand = holder.getBeanDefinition().getOriginatingBeanDefinition(); if (bdCand == null) { bdCand = holder.getBeanDefinition(); } if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) { parse(bdCand.getBeanClassName(), holder.getBeanName()); } } } } // Process any @Import annotations processImports(configClass, sourceClass, getImports(sourceClass), true); // Process any @ImportResource annotations AnnotationAttributes importResource = AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class); if (importResource != null) { String[] resources = importResource.getStringArray("locations"); Class<? extends BeanDefinitionReader> readerClass = importResource.getClass("reader"); for (String resource : resources) { String resolvedResource = this.environment.resolveRequiredPlaceholders(resource); configClass.addImportedResource(resolvedResource, readerClass); } } // Process individual @Bean methods Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass); for (MethodMetadata methodMetadata : beanMethods) { configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass)); } // Process default methods on interfaces processInterfaces(configClass, sourceClass); // Process superclass, if any if (sourceClass.getMetadata().hasSuperClass()) { String superclass = sourceClass.getMetadata().getSuperClassName(); if (superclass != null && !superclass.startsWith("java") && !this.knownSuperclasses.containsKey(superclass)) { this.knownSuperclasses.put(superclass, configClass); // Superclass found, return its annotation metadata and recurse return sourceClass.getSuperClass(); } } // No superclass -> processing is complete return null; } /** * Register member (nested) classes that happen to be configuration classes themselves. */ private void processMemberClasses(ConfigurationClass configClass, SourceClass sourceClass) throws IOException { Collection<SourceClass> memberClasses = sourceClass.getMemberClasses(); if (!memberClasses.isEmpty()) { List<SourceClass> candidates = new ArrayList<>(memberClasses.size()); for (SourceClass memberClass : memberClasses) { if (ConfigurationClassUtils.isConfigurationCandidate(memberClass.getMetadata()) && !memberClass.getMetadata().getClassName().equals(configClass.getMetadata().getClassName())) { candidates.add(memberClass); } } OrderComparator.sort(candidates); for (SourceClass candidate : candidates) { if (this.importStack.contains(configClass)) { this.problemReporter.error(new CircularImportProblem(configClass, this.importStack)); } else { this.importStack.push(configClass); try { processConfigurationClass(candidate.asConfigClass(configClass)); } finally { this.importStack.pop(); } } } } } /** * Register default methods on interfaces implemented by the configuration class. */ private void processInterfaces(ConfigurationClass configClass, SourceClass sourceClass) throws IOException { for (SourceClass ifc : sourceClass.getInterfaces()) { Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(ifc); for (MethodMetadata methodMetadata : beanMethods) { if (!methodMetadata.isAbstract()) { // A default method or other concrete method on a Java 8+ interface... configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass)); } } processInterfaces(configClass, ifc); } } /** * Retrieve the metadata for all <code>@Bean</code> methods. */ private Set<MethodMetadata> retrieveBeanMethodMetadata(SourceClass sourceClass) { AnnotationMetadata original = sourceClass.getMetadata(); Set<MethodMetadata> beanMethods = original.getAnnotatedMethods(Bean.class.getName()); if (beanMethods.size() > 1 && original instanceof StandardAnnotationMetadata) { // Try reading the class file via ASM for deterministic declaration order... // Unfortunately, the JVM‘s standard reflection returns methods in arbitrary // order, even between different runs of the same application on the same JVM. try { AnnotationMetadata asm = this.metadataReaderFactory.getMetadataReader(original.getClassName()).getAnnotationMetadata(); Set<MethodMetadata> asmMethods = asm.getAnnotatedMethods(Bean.class.getName()); if (asmMethods.size() >= beanMethods.size()) { Set<MethodMetadata> selectedMethods = new LinkedHashSet<>(asmMethods.size()); for (MethodMetadata asmMethod : asmMethods) { for (MethodMetadata beanMethod : beanMethods) { if (beanMethod.getMethodName().equals(asmMethod.getMethodName())) { selectedMethods.add(beanMethod); break; } } } if (selectedMethods.size() == beanMethods.size()) { // All reflection-detected methods found in ASM method set -> proceed beanMethods = selectedMethods; } } } catch (IOException ex) { logger.debug("Failed to read class file via ASM for determining @Bean method order", ex); // No worries, let‘s continue with the reflection metadata we started with... } } return beanMethods; } /** * Process the given <code>@PropertySource</code> annotation metadata. * @param propertySource metadata for the <code>@PropertySource</code> annotation found * @throws IOException if loading a property source failed */ private void processPropertySource(AnnotationAttributes propertySource) throws IOException { String name = propertySource.getString("name"); if (!StringUtils.hasLength(name)) { name = null; } String encoding = propertySource.getString("encoding"); if (!StringUtils.hasLength(encoding)) { encoding = null; } String[] locations = propertySource.getStringArray("value"); Assert.isTrue(locations.length > 0, "At least one @PropertySource(value) location is required"); boolean ignoreResourceNotFound = propertySource.getBoolean("ignoreResourceNotFound"); Class<? extends PropertySourceFactory> factoryClass = propertySource.getClass("factory"); PropertySourceFactory factory = (factoryClass == PropertySourceFactory.class ? DEFAULT_PROPERTY_SOURCE_FACTORY : BeanUtils.instantiateClass(factoryClass)); for (String location : locations) { try { String resolvedLocation = this.environment.resolveRequiredPlaceholders(location); Resource resource = this.resourceLoader.getResource(resolvedLocation); addPropertySource(factory.createPropertySource(name, new EncodedResource(resource, encoding))); } catch (IllegalArgumentException | FileNotFoundException | UnknownHostException ex) { // Placeholders not resolvable or resource not found when trying to open it if (ignoreResourceNotFound) { if (logger.isInfoEnabled()) { logger.info("Properties location [" + location + "] not resolvable: " + ex.getMessage()); } } else { throw ex; } } } } private void addPropertySource(PropertySource<?> propertySource) { String name = propertySource.getName(); MutablePropertySources propertySources = ((ConfigurableEnvironment) this.environment).getPropertySources(); if (this.propertySourceNames.contains(name)) { // We‘ve already added a version, we need to extend it PropertySource<?> existing = propertySources.get(name); if (existing != null) { PropertySource<?> newSource = (propertySource instanceof ResourcePropertySource ? ((ResourcePropertySource) propertySource).withResourceName() : propertySource); if (existing instanceof CompositePropertySource) { ((CompositePropertySource) existing).addFirstPropertySource(newSource); } else { if (existing instanceof ResourcePropertySource) { existing = ((ResourcePropertySource) existing).withResourceName(); } CompositePropertySource composite = new CompositePropertySource(name); composite.addPropertySource(newSource); composite.addPropertySource(existing); propertySources.replace(name, composite); } return; } } if (this.propertySourceNames.isEmpty()) { propertySources.addLast(propertySource); } else { String firstProcessed = this.propertySourceNames.get(this.propertySourceNames.size() - 1); propertySources.addBefore(firstProcessed, propertySource); } this.propertySourceNames.add(name); } /** * Returns {@code @Import} class, considering all meta-annotations. */ private Set<SourceClass> getImports(SourceClass sourceClass) throws IOException { Set<SourceClass> imports = new LinkedHashSet<>(); Set<SourceClass> visited = new LinkedHashSet<>(); collectImports(sourceClass, imports, visited); return imports; } /** * Recursively collect all declared {@code @Import} values. Unlike most * meta-annotations it is valid to have several {@code @Import}s declared with * different values; the usual process of returning values from the first * meta-annotation on a class is not sufficient. * <p>For example, it is common for a {@code @Configuration} class to declare direct * {@code @Import}s in addition to meta-imports originating from an {@code @Enable} * annotation. * @param sourceClass the class to search * @param imports the imports collected so far * @param visited used to track visited classes to prevent infinite recursion * @throws IOException if there is any problem reading metadata from the named class */ private void collectImports(SourceClass sourceClass, Set<SourceClass> imports, Set<SourceClass> visited) throws IOException { if (visited.add(sourceClass)) { for (SourceClass annotation : sourceClass.getAnnotations()) { String annName = annotation.getMetadata().getClassName(); if (!annName.startsWith("java") && !annName.equals(Import.class.getName())) { collectImports(annotation, imports, visited); } } imports.addAll(sourceClass.getAnnotationAttributes(Import.class.getName(), "value")); } } private void processDeferredImportSelectors() { List<DeferredImportSelectorHolder> deferredImports = this.deferredImportSelectors; this.deferredImportSelectors = null; if (deferredImports == null) { return; } deferredImports.sort(DEFERRED_IMPORT_COMPARATOR); Map<Object, DeferredImportSelectorGrouping> groupings = new LinkedHashMap<>(); Map<AnnotationMetadata, ConfigurationClass> configurationClasses = new HashMap<>(); for (DeferredImportSelectorHolder deferredImport : deferredImports) { Class<? extends Group> group = deferredImport.getImportSelector().getImportGroup(); DeferredImportSelectorGrouping grouping = groupings.computeIfAbsent( (group == null ? deferredImport : group), (key) -> new DeferredImportSelectorGrouping(createGroup(group))); grouping.add(deferredImport); configurationClasses.put(deferredImport.getConfigurationClass().getMetadata(), deferredImport.getConfigurationClass()); } for (DeferredImportSelectorGrouping grouping : groupings.values()) { grouping.getImports().forEach((entry) -> { ConfigurationClass configurationClass = configurationClasses.get( entry.getMetadata()); try { processImports(configurationClass, asSourceClass(configurationClass), asSourceClasses(entry.getImportClassName()), false); } catch (BeanDefinitionStoreException ex) { throw ex; } catch (Throwable ex) { throw new BeanDefinitionStoreException( "Failed to process import candidates for configuration class [" + configurationClass.getMetadata().getClassName() + "]", ex); } }); } } private Group createGroup(@Nullable Class<? extends Group> type) { Class<? extends Group> effectiveType = (type != null ? type : DefaultDeferredImportSelectorGroup.class); Group group = BeanUtils.instantiateClass(effectiveType); ParserStrategyUtils.invokeAwareMethods(group, ConfigurationClassParser.this.environment, ConfigurationClassParser.this.resourceLoader, ConfigurationClassParser.this.registry); return group; } private void processImports(ConfigurationClass configClass, SourceClass currentSourceClass, Collection<SourceClass> importCandidates, boolean checkForCircularImports) { if (importCandidates.isEmpty()) { return; } if (checkForCircularImports && isChainedImportOnStack(configClass)) { this.problemReporter.error(new CircularImportProblem(configClass, this.importStack)); } else { this.importStack.push(configClass); try { for (SourceClass candidate : importCandidates) { if (candidate.isAssignable(ImportSelector.class)) { // Candidate class is an ImportSelector -> delegate to it to determine imports Class<?> candidateClass = candidate.loadClass(); ImportSelector selector = BeanUtils.instantiateClass(candidateClass, ImportSelector.class); ParserStrategyUtils.invokeAwareMethods( selector, this.environment, this.resourceLoader, this.registry); if (this.deferredImportSelectors != null && selector instanceof DeferredImportSelector) { this.deferredImportSelectors.add( new DeferredImportSelectorHolder(configClass, (DeferredImportSelector) selector)); } else { String[] importClassNames = selector.selectImports(currentSourceClass.getMetadata()); Collection<SourceClass> importSourceClasses = asSourceClasses(importClassNames); processImports(configClass, currentSourceClass, importSourceClasses, false); } } else if (candidate.isAssignable(ImportBeanDefinitionRegistrar.class)) { // Candidate class is an ImportBeanDefinitionRegistrar -> // delegate to it to register additional bean definitions Class<?> candidateClass = candidate.loadClass(); ImportBeanDefinitionRegistrar registrar = BeanUtils.instantiateClass(candidateClass, ImportBeanDefinitionRegistrar.class); ParserStrategyUtils.invokeAwareMethods( registrar, this.environment, this.resourceLoader, this.registry); configClass.addImportBeanDefinitionRegistrar(registrar, currentSourceClass.getMetadata()); } else { // Candidate class not an ImportSelector or ImportBeanDefinitionRegistrar -> // process it as an @Configuration class this.importStack.registerImport( currentSourceClass.getMetadata(), candidate.getMetadata().getClassName()); processConfigurationClass(candidate.asConfigClass(configClass)); } } } catch (BeanDefinitionStoreException ex) { throw ex; } catch (Throwable ex) { throw new BeanDefinitionStoreException( "Failed to process import candidates for configuration class [" + configClass.getMetadata().getClassName() + "]", ex); } finally { this.importStack.pop(); } } } private boolean isChainedImportOnStack(ConfigurationClass configClass) { if (this.importStack.contains(configClass)) { String configClassName = configClass.getMetadata().getClassName(); AnnotationMetadata importingClass = this.importStack.getImportingClassFor(configClassName); while (importingClass != null) { if (configClassName.equals(importingClass.getClassName())) { return true; } importingClass = this.importStack.getImportingClassFor(importingClass.getClassName()); } } return false; } ImportRegistry getImportRegistry() { return this.importStack; } /** * Factory method to obtain a {@link SourceClass} from a {@link ConfigurationClass}. */ private SourceClass asSourceClass(ConfigurationClass configurationClass) throws IOException { AnnotationMetadata metadata = configurationClass.getMetadata(); if (metadata instanceof StandardAnnotationMetadata) { return asSourceClass(((StandardAnnotationMetadata) metadata).getIntrospectedClass()); } return asSourceClass(metadata.getClassName()); } /** * Factory method to obtain a {@link SourceClass} from a {@link Class}. */ SourceClass asSourceClass(@Nullable Class<?> classType) throws IOException { if (classType == null) { return new SourceClass(Object.class); } try { // Sanity test that we can reflectively read annotations, // including Class attributes; if not -> fall back to ASM for (Annotation ann : classType.getAnnotations()) { AnnotationUtils.validateAnnotation(ann); } return new SourceClass(classType); } catch (Throwable ex) { // Enforce ASM via class name resolution return asSourceClass(classType.getName()); } } /** * Factory method to obtain {@link SourceClass}s from class names. */ private Collection<SourceClass> asSourceClasses(String... classNames) throws IOException { List<SourceClass> annotatedClasses = new ArrayList<>(classNames.length); for (String className : classNames) { annotatedClasses.add(asSourceClass(className)); } return annotatedClasses; } /** * Factory method to obtain a {@link SourceClass} from a class name. */ SourceClass asSourceClass(@Nullable String className) throws IOException { if (className == null) { return new SourceClass(Object.class); } if (className.startsWith("java")) { // Never use ASM for core java types try { return new SourceClass(ClassUtils.forName(className, this.resourceLoader.getClassLoader())); } catch (ClassNotFoundException ex) { throw new NestedIOException("Failed to load class [" + className + "]", ex); } } return new SourceClass(this.metadataReaderFactory.getMetadataReader(className)); } @SuppressWarnings("serial") private static class ImportStack extends ArrayDeque<ConfigurationClass> implements ImportRegistry { private final MultiValueMap<String, AnnotationMetadata> imports = new LinkedMultiValueMap<>(); public void registerImport(AnnotationMetadata importingClass, String importedClass) { this.imports.add(importedClass, importingClass); } @Override @Nullable public AnnotationMetadata getImportingClassFor(String importedClass) { return CollectionUtils.lastElement(this.imports.get(importedClass)); } @Override public void removeImportingClass(String importingClass) { for (List<AnnotationMetadata> list : this.imports.values()) { for (Iterator<AnnotationMetadata> iterator = list.iterator(); iterator.hasNext();) { if (iterator.next().getClassName().equals(importingClass)) { iterator.remove(); break; } } } } /** * Given a stack containing (in order) * <ul> * <li>com.acme.Foo</li> * <li>com.acme.Bar</li> * <li>com.acme.Baz</li> * </ul> * return "[Foo->Bar->Baz]". */ @Override public String toString() { StringBuilder builder = new StringBuilder("["); Iterator<ConfigurationClass> iterator = iterator(); while (iterator.hasNext()) { builder.append(iterator.next().getSimpleName()); if (iterator.hasNext()) { builder.append("->"); } } return builder.append(‘]‘).toString(); } } private static class DeferredImportSelectorHolder { private final ConfigurationClass configurationClass; private final DeferredImportSelector importSelector; public DeferredImportSelectorHolder(ConfigurationClass configClass, DeferredImportSelector selector) { this.configurationClass = configClass; this.importSelector = selector; } public ConfigurationClass getConfigurationClass() { return this.configurationClass; } public DeferredImportSelector getImportSelector() { return this.importSelector; } } private static class DeferredImportSelectorGrouping { private final DeferredImportSelector.Group group; private final List<DeferredImportSelectorHolder> deferredImports = new ArrayList<>(); DeferredImportSelectorGrouping(Group group) { this.group = group; } public void add(DeferredImportSelectorHolder deferredImport) { this.deferredImports.add(deferredImport); } /** * Return the imports defined by the group. * @return each import with its associated configuration class */ public Iterable<Group.Entry> getImports() { for (DeferredImportSelectorHolder deferredImport : this.deferredImports) { this.group.process(deferredImport.getConfigurationClass().getMetadata(), deferredImport.getImportSelector()); } return this.group.selectImports(); } } private static class DefaultDeferredImportSelectorGroup implements Group { private final List<Entry> imports = new ArrayList<>(); @Override public void process(AnnotationMetadata metadata, DeferredImportSelector selector) { for (String importClassName : selector.selectImports(metadata)) { this.imports.add(new Entry(metadata, importClassName)); } } @Override public Iterable<Entry> selectImports() { return this.imports; } } /** * Simple wrapper that allows annotated source classes to be dealt with * in a uniform manner, regardless of how they are loaded. */ private class SourceClass implements Ordered { private final Object source; // Class or MetadataReader private final AnnotationMetadata metadata; public SourceClass(Object source) { this.source = source; if (source instanceof Class) { this.metadata = new StandardAnnotationMetadata((Class<?>) source, true); } else { this.metadata = ((MetadataReader) source).getAnnotationMetadata(); } } public final AnnotationMetadata getMetadata() { return this.metadata; } @Override public int getOrder() { Integer order = ConfigurationClassUtils.getOrder(this.metadata); return (order != null ? order : Ordered.LOWEST_PRECEDENCE); } public Class<?> loadClass() throws ClassNotFoundException { if (this.source instanceof Class) { return (Class<?>) this.source; } String className = ((MetadataReader) this.source).getClassMetadata().getClassName(); return ClassUtils.forName(className, resourceLoader.getClassLoader()); } public boolean isAssignable(Class<?> clazz) throws IOException { if (this.source instanceof Class) { return clazz.isAssignableFrom((Class<?>) this.source); } return new AssignableTypeFilter(clazz).match((MetadataReader) this.source, metadataReaderFactory); } public ConfigurationClass asConfigClass(ConfigurationClass importedBy) throws IOException { if (this.source instanceof Class) { return new ConfigurationClass((Class<?>) this.source, importedBy); } return new ConfigurationClass((MetadataReader) this.source, importedBy); } public Collection<SourceClass> getMemberClasses() throws IOException { Object sourceToProcess = this.source; if (sourceToProcess instanceof Class) { Class<?> sourceClass = (Class<?>) sourceToProcess; try { Class<?>[] declaredClasses = sourceClass.getDeclaredClasses(); List<SourceClass> members = new ArrayList<>(declaredClasses.length); for (Class<?> declaredClass : declaredClasses) { members.add(asSourceClass(declaredClass)); } return members; } catch (NoClassDefFoundError err) { // getDeclaredClasses() failed because of non-resolvable dependencies // -> fall back to ASM below sourceToProcess = metadataReaderFactory.getMetadataReader(sourceClass.getName()); } } // ASM-based resolution - safe for non-resolvable classes as well MetadataReader sourceReader = (MetadataReader) sourceToProcess; String[] memberClassNames = sourceReader.getClassMetadata().getMemberClassNames(); List<SourceClass> members = new ArrayList<>(memberClassNames.length); for (String memberClassName : memberClassNames) { try { members.add(asSourceClass(memberClassName)); } catch (IOException ex) { // Let‘s skip it if it‘s not resolvable - we‘re just looking for candidates if (logger.isDebugEnabled()) { logger.debug("Failed to resolve member class [" + memberClassName + "] - not considering it as a configuration class candidate"); } } } return members; } public SourceClass getSuperClass() throws IOException { if (this.source instanceof Class) { return asSourceClass(((Class<?>) this.source).getSuperclass()); } return asSourceClass(((MetadataReader) this.source).getClassMetadata().getSuperClassName()); } public Set<SourceClass> getInterfaces() throws IOException { Set<SourceClass> result = new LinkedHashSet<>(); if (this.source instanceof Class) { Class<?> sourceClass = (Class<?>) this.source; for (Class<?> ifcClass : sourceClass.getInterfaces()) { result.add(asSourceClass(ifcClass)); } } else { for (String className : this.metadata.getInterfaceNames()) { result.add(asSourceClass(className)); } } return result; } public Set<SourceClass> getAnnotations() throws IOException { Set<SourceClass> result = new LinkedHashSet<>(); for (String className : this.metadata.getAnnotationTypes()) { try { result.add(getRelated(className)); } catch (Throwable ex) { // An annotation not present on the classpath is being ignored // by the JVM‘s class loading -> ignore here as well. } } return result; } public Collection<SourceClass> getAnnotationAttributes(String annType, String attribute) throws IOException { Map<String, Object> annotationAttributes = this.metadata.getAnnotationAttributes(annType, true); if (annotationAttributes == null || !annotationAttributes.containsKey(attribute)) { return Collections.emptySet(); } String[] classNames = (String[]) annotationAttributes.get(attribute); Set<SourceClass> result = new LinkedHashSet<>(); for (String className : classNames) { result.add(getRelated(className)); } return result; } private SourceClass getRelated(String className) throws IOException { if (this.source instanceof Class) { try { Class<?> clazz = ((Class<?>) this.source).getClassLoader().loadClass(className); return asSourceClass(clazz); } catch (ClassNotFoundException ex) { // Ignore -> fall back to ASM next, except for core java types. if (className.startsWith("java")) { throw new NestedIOException("Failed to load class [" + className + "]", ex); } return new SourceClass(metadataReaderFactory.getMetadataReader(className)); } } return asSourceClass(className); } @Override public boolean equals(Object other) { return (this == other || (other instanceof SourceClass && this.metadata.getClassName().equals(((SourceClass) other).metadata.getClassName()))); } @Override public int hashCode() { return this.metadata.getClassName().hashCode(); } @Override public String toString() { return this.metadata.getClassName(); } } /** * {@link Problem} registered upon detection of a circular {@link Import}. */ private static class CircularImportProblem extends Problem { public CircularImportProblem(ConfigurationClass attemptedImport, Deque<ConfigurationClass> importStack) { super(String.format("A circular @Import has been detected: " + "Illegal attempt by @Configuration class ‘%s‘ to import class ‘%s‘ as ‘%s‘ is " + "already present in the current import stack %s", importStack.element().getSimpleName(), attemptedImport.getSimpleName(), attemptedImport.getSimpleName(), importStack), new Location(importStack.element().getResource(), attemptedImport.getMetadata())); } } }
注意parse方法的最后一句processDeferredImportSelectors方法,在这里将会对DeferredImportSelector进行处理,这样我们就和AutoConfigurationSelectImporter结合到一起了。
注意processDeferredImportSelectors中的
Class<? extends Group> group = deferredImport.getImportSelector().getImportGroup();这句代码
这里deferredImport的类型为DeferredImportSelectorHolder:
private static class DeferredImportSelectorHolder { private final ConfigurationClass configurationClass; private final DeferredImportSelector importSelector; public DeferredImportSelectorHolder(ConfigurationClass configClass, DeferredImportSelector selector) { this.configurationClass = configClass; this.importSelector = selector; } public ConfigurationClass getConfigurationClass() { return this.configurationClass; } public DeferredImportSelector getImportSelector() { return this.importSelector; } }
在这个内部类里持有了一个DeferredImportSelector的引用,至此将会执行自动装配的所有操作
ㄟ( ▔, ▔ )ㄏ
原文地址:https://www.cnblogs.com/yanfeiLiu/p/9304049.html