在Spring IOC容器的设计中，有两个主要的容器系列，一个是实现BeanFactory接口的简单容器系列，这系列容器只实现了容器的最基本功能；另一个是ApplicationContext应用上下文，它作为容器的高级形态而存在。应用上下文在简单容器的基础上，增加了许多面向框架的特性，同时对应用环境做了许多适配。
用户在使用容器时，可以使用转义符“&”来得到FactoryBean本身，用来区分通过容器来获得FactoryBean产生的对象和获取FactoryBean本身。例如，如果MyBean是一个FactoryBean，那么使用&MyBean得到的是FactoryBean，而不是MyBean这个FactoryBean产生出来的对象。
BeanFactory接口设计了getBean()方法，通过这个方法可以得到IOC容器中管理的bean，bean的去的是通过指定名字来索引的。
用户可以执行以下操作：
1.通过接口方法constainsBean让用户能够判断容器事都含有指定名字的Bean。
2.通过接口方法isSingleton来查询指定名字的Bean是否是Singleton类型的Bean。对于Singleton属性，用户可以在BeanDefinition中指定。
3.通过接口方法isPrototype来查询指定名字的Bean是否是prototype类型的。与Singleton属性是一样的，这个属性也可以由用户在BeanDefinition中指定。
4.通过接口方法isTypeMatch来查询指定了名字的Bean的Class类型是否是特定的Class类型。这个Class类型可以由用户来指定。
5.通过接口方法getType来查询指定名字的Bean的Class类型。
6.通过接口方法getAliases来查询指定了名字的Bean的所有别名，这些别名都是由用户在Beandefinition中定义的。
1 /*
2 * Copyright 2002-2013 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.springframework.beans.factory;
18
19 import org.springframework.beans.BeansException;
20
21 /**
22 * The root interface for accessing a Spring bean container.
23 * This is the basic client view of a bean container;
24 * further interfaces such as {@link ListableBeanFactory} and
25 * {@link org.springframework.beans.factory.config.ConfigurableBeanFactory}
26 * are available for specific purposes.
27 *
28 * <p>This interface is implemented by objects that hold a number of bean definitions,
29 * each uniquely identified by a String name. Depending on the bean definition,
30 * the factory will return either an independent instance of a contained object
31 * (the Prototype design pattern), or a single shared instance (a superior
32 * alternative to the Singleton design pattern, in which the instance is a
33 * singleton in the scope of the factory). Which type of instance will be returned
34 * depends on the bean factory configuration: the API is the same. Since Spring
35 * 2.0, further scopes are available depending on the concrete application
36 * context (e.g. "request" and "session" scopes in a web environment).
37 *
38 * <p>The point of this approach is that the BeanFactory is a central registry
39 * of application components, and centralizes configuration of application
40 * components (no more do individual objects need to read properties files,
41 * for example). See chapters 4 and 11 of "Expert One-on-One J2EE Design and
42 * Development" for a discussion of the benefits of this approach.
43 *
44 * <p>Note that it is generally better to rely on Dependency Injection
45 * ("push" configuration) to configure application objects through setters
46 * or constructors, rather than use any form of "pull" configuration like a
47 * BeanFactory lookup. Spring‘s Dependency Injection functionality is
48 * implemented using this BeanFactory interface and its subinterfaces.
49 *
50 * <p>Normally a BeanFactory will load bean definitions stored in a configuration
51 * source (such as an XML document), and use the {@code org.springframework.beans}
52 * package to configure the beans. However, an implementation could simply return
53 * Java objects it creates as necessary directly in Java code. There are no
54 * constraints on how the definitions could be stored: LDAP, RDBMS, XML,
55 * properties file, etc. Implementations are encouraged to support references
56 * amongst beans (Dependency Injection).
57 *
58 * <p>In contrast to the methods in {@link ListableBeanFactory}, all of the
59 * operations in this interface will also check parent factories if this is a
60 * {@link HierarchicalBeanFactory}. If a bean is not found in this factory instance,
61 * the immediate parent factory will be asked. Beans in this factory instance
62 * are supposed to override beans of the same name in any parent factory.
63 *
64 * <p>Bean factory implementations should support the standard bean lifecycle interfaces
65 * as far as possible. The full set of initialization methods and their standard order is:<br>
66 * 1. BeanNameAware‘s {@code setBeanName}<br>
67 * 2. BeanClassLoaderAware‘s {@code setBeanClassLoader}<br>
68 * 3. BeanFactoryAware‘s {@code setBeanFactory}<br>
69 * 4. ResourceLoaderAware‘s {@code setResourceLoader}
70 * (only applicable when running in an application context)<br>
71 * 5. ApplicationEventPublisherAware‘s {@code setApplicationEventPublisher}
72 * (only applicable when running in an application context)<br>
73 * 6. MessageSourceAware‘s {@code setMessageSource}
74 * (only applicable when running in an application context)<br>
75 * 7. ApplicationContextAware‘s {@code setApplicationContext}
76 * (only applicable when running in an application context)<br>
77 * 8. ServletContextAware‘s {@code setServletContext}
78 * (only applicable when running in a web application context)<br>
79 * 9. {@code postProcessBeforeInitialization} methods of BeanPostProcessors<br>
80 * 10. InitializingBean‘s {@code afterPropertiesSet}<br>
81 * 11. a custom init-method definition<br>
82 * 12. {@code postProcessAfterInitialization} methods of BeanPostProcessors
83 *
84 * <p>On shutdown of a bean factory, the following lifecycle methods apply:<br>
85 * 1. DisposableBean‘s {@code destroy}<br>
86 * 2. a custom destroy-method definition
87 *
88 * @author Rod Johnson
89 * @author Juergen Hoeller
90 * @author Chris Beams
91 * @since 13 April 2001
92 * @see BeanNameAware#setBeanName
93 * @see BeanClassLoaderAware#setBeanClassLoader
94 * @see BeanFactoryAware#setBeanFactory
95 * @see org.springframework.context.ResourceLoaderAware#setResourceLoader
96 * @see org.springframework.context.ApplicationEventPublisherAware#setApplicationEventPublisher
97 * @see org.springframework.context.MessageSourceAware#setMessageSource
98 * @see org.springframework.context.ApplicationContextAware#setApplicationContext
99 * @see org.springframework.web.context.ServletContextAware#setServletContext
100 * @see org.springframework.beans.factory.config.BeanPostProcessor#postProcessBeforeInitialization
101 * @see InitializingBean#afterPropertiesSet
102 * @see org.springframework.beans.factory.support.RootBeanDefinition#getInitMethodName
103 * @see org.springframework.beans.factory.config.BeanPostProcessor#postProcessAfterInitialization
104 * @see DisposableBean#destroy
105 * @see org.springframework.beans.factory.support.RootBeanDefinition#getDestroyMethodName
106 */
107 public interface BeanFactory {
108
109 /**
110 * Used to dereference a {@link FactoryBean} instance and distinguish it from
111 * beans <i>created</i> by the FactoryBean. For example, if the bean named
112 * {@code myJndiObject} is a FactoryBean, getting {@code &myJndiObject}
113 * will return the factory, not the instance returned by the factory.
114 */
115 String FACTORY_BEAN_PREFIX = "&";
116
117 /**
118 * Return an instance, which may be shared or independent, of the specified bean.
119 * <p>This method allows a Spring BeanFactory to be used as a replacement for the
120 * Singleton or Prototype design pattern. Callers may retain references to
121 * returned objects in the case of Singleton beans.
122 * <p>Translates aliases back to the corresponding canonical bean name.
123 * Will ask the parent factory if the bean cannot be found in this factory instance.
124 * @param name the name of the bean to retrieve
125 * @return an instance of the bean
126 * @throws NoSuchBeanDefinitionException if there is no bean definition
127 * with the specified name
128 * @throws BeansException if the bean could not be obtained
129 */
130 Object getBean(String name) throws BeansException;
131
132 /**
133 * Return an instance, which may be shared or independent, of the specified bean.
134 * <p>Behaves the same as {@link #getBean(String)}, but provides a measure of type
135 * safety by throwing a BeanNotOfRequiredTypeException if the bean is not of the
136 * required type. This means that ClassCastException can‘t be thrown on casting
137 * the result correctly, as can happen with {@link #getBean(String)}.
138 * <p>Translates aliases back to the corresponding canonical bean name.
139 * Will ask the parent factory if the bean cannot be found in this factory instance.
140 * @param name the name of the bean to retrieve
141 * @param requiredType type the bean must match. Can be an interface or superclass
142 * of the actual class, or {@code null} for any match. For example, if the value
143 * is {@code Object.class}, this method will succeed whatever the class of the
144 * returned instance.
145 * @return an instance of the bean
146 * @throws NoSuchBeanDefinitionException if there is no such bean definition
147 * @throws BeanNotOfRequiredTypeException if the bean is not of the required type
148 * @throws BeansException if the bean could not be created
149 */
150 <T> T getBean(String name, Class<T> requiredType) throws BeansException;
151
152 /**
153 * Return the bean instance that uniquely matches the given object type, if any.
154 * @param requiredType type the bean must match; can be an interface or superclass.
155 * {@code null} is disallowed.
156 * <p>This method goes into {@link ListableBeanFactory} by-type lookup territory
157 * but may also be translated into a conventional by-name lookup based on the name
158 * of the given type. For more extensive retrieval operations across sets of beans,
159 * use {@link ListableBeanFactory} and/or {@link BeanFactoryUtils}.
160 * @return an instance of the single bean matching the required type
161 * @throws NoSuchBeanDefinitionException if no bean of the given type was found
162 * @throws NoUniqueBeanDefinitionException if more than one bean of the given type was found
163 * @since 3.0
164 * @see ListableBeanFactory
165 */
166 <T> T getBean(Class<T> requiredType) throws BeansException;
167
168 /**
169 * Return an instance, which may be shared or independent, of the specified bean.
170 * <p>Allows for specifying explicit constructor arguments / factory method arguments,
171 * overriding the specified default arguments (if any) in the bean definition.
172 * @param name the name of the bean to retrieve
173 * @param args arguments to use if creating a prototype using explicit arguments to a
174 * static factory method. It is invalid to use a non-null args value in any other case.
175 * @return an instance of the bean
176 * @throws NoSuchBeanDefinitionException if there is no such bean definition
177 * @throws BeanDefinitionStoreException if arguments have been given but
178 * the affected bean isn‘t a prototype
179 * @throws BeansException if the bean could not be created
180 * @since 2.5
181 */
182 Object getBean(String name, Object... args) throws BeansException;
183
184 /**
185 * Does this bean factory contain a bean definition or externally registered singleton
186 * instance with the given name?
187 * <p>If the given name is an alias, it will be translated back to the corresponding
188 * canonical bean name.
189 * <p>If this factory is hierarchical, will ask any parent factory if the bean cannot
190 * be found in this factory instance.
191 * <p>If a bean definition or singleton instance matching the given name is found,
192 * this method will return {@code true} whether the named bean definition is concrete
193 * or abstract, lazy or eager, in scope or not. Therefore, note that a {@code true}
194 * return value from this method does not necessarily indicate that {@link #getBean}
195 * will be able to obtain an instance for the same name.
196 * @param name the name of the bean to query
197 * @return whether a bean with the given name is present
198 */
199 boolean containsBean(String name);
200
201 /**
202 * Is this bean a shared singleton? That is, will {@link #getBean} always
203 * return the same instance?
204 * <p>Note: This method returning {@code false} does not clearly indicate
205 * independent instances. It indicates non-singleton instances, which may correspond
206 * to a scoped bean as well. Use the {@link #isPrototype} operation to explicitly
207 * check for independent instances.
208 * <p>Translates aliases back to the corresponding canonical bean name.
209 * Will ask the parent factory if the bean cannot be found in this factory instance.
210 * @param name the name of the bean to query
211 * @return whether this bean corresponds to a singleton instance
212 * @throws NoSuchBeanDefinitionException if there is no bean with the given name
213 * @see #getBean
214 * @see #isPrototype
215 */
216 boolean isSingleton(String name) throws NoSuchBeanDefinitionException;
217
218 /**
219 * Is this bean a prototype? That is, will {@link #getBean} always return
220 * independent instances?
221 * <p>Note: This method returning {@code false} does not clearly indicate
222 * a singleton object. It indicates non-independent instances, which may correspond
223 * to a scoped bean as well. Use the {@link #isSingleton} operation to explicitly
224 * check for a shared singleton instance.
225 * <p>Translates aliases back to the corresponding canonical bean name.
226 * Will ask the parent factory if the bean cannot be found in this factory instance.
227 * @param name the name of the bean to query
228 * @return whether this bean will always deliver independent instances
229 * @throws NoSuchBeanDefinitionException if there is no bean with the given name
230 * @since 2.0.3
231 * @see #getBean
232 * @see #isSingleton
233 */
234 boolean isPrototype(String name) throws NoSuchBeanDefinitionException;
235
236 /**
237 * Check whether the bean with the given name matches the specified type.
238 * More specifically, check whether a {@link #getBean} call for the given name
239 * would return an object that is assignable to the specified target type.
240 * <p>Translates aliases back to the corresponding canonical bean name.
241 * Will ask the parent factory if the bean cannot be found in this factory instance.
242 * @param name the name of the bean to query
243 * @param targetType the type to match against
244 * @return {@code true} if the bean type matches,
245 * {@code false} if it doesn‘t match or cannot be determined yet
246 * @throws NoSuchBeanDefinitionException if there is no bean with the given name
247 * @since 2.0.1
248 * @see #getBean
249 * @see #getType
250 */
251 boolean isTypeMatch(String name, Class<?> targetType) throws NoSuchBeanDefinitionException;
252
253 /**
254 * Determine the type of the bean with the given name. More specifically,
255 * determine the type of object that {@link #getBean} would return for the given name.
256 * <p>For a {@link FactoryBean}, return the type of object that the FactoryBean creates,
257 * as exposed by {@link FactoryBean#getObjectType()}.
258 * <p>Translates aliases back to the corresponding canonical bean name.
259 * Will ask the parent factory if the bean cannot be found in this factory instance.
260 * @param name the name of the bean to query
261 * @return the type of the bean, or {@code null} if not determinable
262 * @throws NoSuchBeanDefinitionException if there is no bean with the given name
263 * @since 1.1.2
264 * @see #getBean
265 * @see #isTypeMatch
266 */
267 Class<?> getType(String name) throws NoSuchBeanDefinitionException;
268
269 /**
270 * Return the aliases for the given bean name, if any.
271 * All of those aliases point to the same bean when used in a {@link #getBean} call.
272 * <p>If the given name is an alias, the corresponding original bean name
273 * and other aliases (if any) will be returned, with the original bean name
274 * being the first element in the array.
275 * <p>Will ask the parent factory if the bean cannot be found in this factory instance.
276 * @param name the bean name to check for aliases
277 * @return the aliases, or an empty array if none
278 * @see #getBean
279 */
280 String[] getAliases(String name);
281
282 }
时间： 2024-11-10 17:31:39