Spring MVC 指导文档解读（二）

Special Bean Types In the WebApplicationContext

解读

1.WebApplicationContext 特有的几种 Bean Types

2. 也表明 与之相对的 还有 ApplicationContext

下面这几种特有的 web bean types 也理应定义到 web 的上下文配置文件中，比如 a-servlet.xml

Table 22.1. Special bean types in the WebApplicationContext

查看dispatcherServlet 相关日志

Line 2: 2016-10-04 13:07:57 DEBUG DispatcherServlet:118 - Initializing servlet ‘dispatcher‘
Line 9: 2016-10-04 13:07:57 INFO  DispatcherServlet:489 - FrameworkServlet ‘dispatcher‘: initialization started
Line 10: 2016-10-04 13:07:57 DEBUG DispatcherServlet:617 - Servlet with name ‘dispatcher‘ will try to create custom WebApplicationContext context of class ‘org.springframework.web.context.support.XmlWebApplicationContext‘, using parent context [null]
Line 577: 2016-10-04 13:07:59 DEBUG DispatcherServlet:511 - Unable to locate MultipartResolver with name ‘multipartResolver‘: no multipart request handling provided
Line 586: 2016-10-04 13:07:59 DEBUG DispatcherServlet:533 - Unable to locate LocaleResolver with name ‘localeResolver‘: using default [[email protected]3af54caa]
Line 594: 2016-10-04 13:07:59 DEBUG DispatcherServlet:555 - Unable to locate ThemeResolver with name ‘themeResolver‘: using default [[email protected]]
Line 619: 2016-10-04 13:07:59 DEBUG DispatcherServlet:692 - Unable to locate RequestToViewNameTranslator with name ‘viewNameTranslator‘: using default [org.spri[email protected]4a233666]
Line 629: 2016-10-04 13:07:59 DEBUG DispatcherServlet:753 - Unable to locate FlashMapManager with name ‘flashMapManager‘: using default [org.springframework.web.servlet.support.S[email protected]]
Line 643: 2016-10-04 13:07:59 DEBUG DispatcherServlet:568 - Published WebApplicationContext of servlet ‘dispatcher‘ as ServletContext attribute with name [org.springframework.web.servlet.FrameworkServlet.CONTEXT.dispatcher]
Line 644: 2016-10-04 13:07:59 INFO  DispatcherServlet:508 - FrameworkServlet ‘dispatcher‘: initialization completed in 1538 ms
Line 645: 2016-10-04 13:07:59 DEBUG DispatcherServlet:139 - Servlet ‘dispatcher‘ configured successfully

dispatcherServlet 干了什么

1. 设置默认的策略（位于DispatcherServlet.properties 中）

    static {
        // Load default strategy implementations from properties file.
        // This is currently strictly internal and not meant to be customized
        // by application developers.
        try {
            ClassPathResource resource = new ClassPathResource(DEFAULT_STRATEGIES_PATH, DispatcherServlet.class);
            defaultStrategies = PropertiesLoaderUtils.loadProperties(resource);
        }
        catch (IOException ex) {
            throw new IllegalStateException("Could not load ‘DispatcherServlet.properties‘: " + ex.getMessage());
        }
    }

# Default implementation classes for DispatcherServlet‘s strategy interfaces.
# Used as fallback when no matching beans are found in the DispatcherServlet context.
# Not meant to be customized by application developers.

org.springframework.web.servlet.LocaleResolver=org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver

org.springframework.web.servlet.ThemeResolver=org.springframework.web.servlet.theme.FixedThemeResolver

org.springframework.web.servlet.HandlerMapping=org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping,	org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping

org.springframework.web.servlet.HandlerAdapter=org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,	org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter,	org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter

org.springframework.web.servlet.HandlerExceptionResolver=org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver,	org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver,	org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver

org.springframework.web.servlet.RequestToViewNameTranslator=org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator

org.springframework.web.servlet.ViewResolver=org.springframework.web.servlet.view.InternalResourceViewResolver

DispatcherServlet.properties

2. 初始化

    protected void initStrategies(ApplicationContext context) {
        initMultipartResolver(context);
        initLocaleResolver(context);
        initThemeResolver(context);
        initHandlerMappings(context);
        initHandlerAdapters(context);
        initHandlerExceptionResolvers(context);
        initRequestToViewNameTranslator(context);
        initViewResolvers(context);
    }

举例来说就是存在指定的就用指定的，不存在指定的就用默认的

    private void initRequestToViewNameTranslator(ApplicationContext context) {
        try {
            this.viewNameTranslator =
                    context.getBean(REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME, RequestToViewNameTranslator.class);
            if (logger.isDebugEnabled()) {
                logger.debug("Using RequestToViewNameTranslator [" + this.viewNameTranslator + "]");
            }
        }
        catch (NoSuchBeanDefinitionException ex) {
            // We need to use the default.
            this.viewNameTranslator = getDefaultStrategy(context, RequestToViewNameTranslator.class);
            if (logger.isDebugEnabled()) {
                logger.debug("Unable to locate RequestToViewNameTranslator with name ‘" +
                        REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME + "‘: using default [" + this.viewNameTranslator +
                        "]");
            }
        }
    }

这便是上面的日志的原因