SpringMVC之分析AnnotationDrivenBeanDefinitionParser(三)

我们在之前的文章中对这篇文章中AnnotationDrivenBeanDefinitionParser的parse方法进行了一些分析，我们在这篇文章中接着分析AnnotationDrivenBeanDefinitionParser的parse方法的内容。

ManagedList<?> messageConverters = getMessageConverters(element, source, parserContext);

private ManagedList<?> getMessageConverters(Element element, Object source, ParserContext parserContext) {//解析message-converters的标签//格式如下：/*    <mvc:annotation-driven><mvc:message-converters><bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/><bean class="org.springframework.http.converter.StringHttpMessageConverter"><property name="supportedMediaTypes"><list><value>text/html;charset=UTF-8</value><value>application/javascript;charset=UTF-8</value></list></property></bean></mvc:message-converters></mvc:annotation-driven>*/Element convertersElement = DomUtils.getChildElementByTagName(element, "message-converters");//存放自己配置的HttpMessageConverterManagedList<? super Object> messageConverters = new ManagedList<Object>();if (convertersElement != null) {messageConverters.setSource(source);//解析自己配置的HttpMessageConverter的beanfor (Element beanElement : DomUtils.getChildElementsByTagName(convertersElement, "bean", "ref")) {Object object = parserContext.getDelegate().parsePropertySubElement(beanElement, null);messageConverters.add(object);}}//如果没有配置<mvc:message-converters>或者register-defaults的值为true 默认为trueif (convertersElement == null || Boolean.valueOf(convertersElement.getAttribute("register-defaults"))) {messageConverters.setSource(source);//添加ByteArrayHttpMessageConverter的BeanDefinitionmessageConverters.add(createConverterDefinition(ByteArrayHttpMessageConverter.class, source));//添加StringHttpMessageConverter的BeanDefinitionRootBeanDefinition stringConverterDef = createConverterDefinition(StringHttpMessageConverter.class, source);stringConverterDef.getPropertyValues().add("writeAcceptCharset", false);messageConverters.add(stringConverterDef);//添加ResourceHttpMessageConverter的BeanDefinitionmessageConverters.add(createConverterDefinition(ResourceHttpMessageConverter.class, source));//添加SourceHttpMessageConverter的BeanDefinitionmessageConverters.add(createConverterDefinition(SourceHttpMessageConverter.class, source));//添加AllEncompassingFormHttpMessageConverter的BeanDefinitionmessageConverters.add(createConverterDefinition(AllEncompassingFormHttpMessageConverter.class, source));//如果有Classpath下面有 com.rometools.rome.feed.WireFeed，则添加//AtomFeedHttpMessageConverter和RssChannelHttpMessageConverter的BeanDefinitionif (romePresent) {messageConverters.add(createConverterDefinition(AtomFeedHttpMessageConverter.class, source));messageConverters.add(createConverterDefinition(RssChannelHttpMessageConverter.class, source));}//如果有Classpath下面有 com.fasterxml.jackson.dataformat.xml.XmlMapper，则添加//MappingJackson2XmlHttpMessageConverter和RssChannelHttpMessageConverter的BeanDefinitionif (jackson2XmlPresent) {RootBeanDefinition jacksonConverterDef = createConverterDefinition(MappingJackson2XmlHttpMessageConverter.class, source);//创建Jackson2ObjectMapperFactoryBean的BeanDefinitionGenericBeanDefinition jacksonFactoryDef = createObjectMapperFactoryDefinition(source);jacksonFactoryDef.getPropertyValues().add("createXmlMapper", true);jacksonConverterDef.getConstructorArgumentValues().addIndexedArgumentValue(0, jacksonFactoryDef);messageConverters.add(jacksonConverterDef);}//如果有Classpath下面有 javax.xml.bind.Binder，则添加//Jaxb2RootElementHttpMessageConverter的BeanDefinitionelse if (jaxb2Present) {messageConverters.add(createConverterDefinition(Jaxb2RootElementHttpMessageConverter.class, source));}//如果有Classpath下面有 com.fasterxml.jackson.databind.ObjectMapper和Jaxb2RootElementHttpMessageConverter的BeanDefinition，则添加//MappingJackson2HttpMessageConverter的BeanDefinitionif (jackson2Present) {RootBeanDefinition jacksonConverterDef = createConverterDefinition(MappingJackson2HttpMessageConverter.class, source);//创建Jackson2ObjectMapperFactoryBean的BeanDefinitionGenericBeanDefinition jacksonFactoryDef = createObjectMapperFactoryDefinition(source);//添加到MappingJackson2HttpMessageConverter的构造函数中jacksonConverterDef.getConstructorArgumentValues().addIndexedArgumentValue(0, jacksonFactoryDef);messageConverters.add(jacksonConverterDef);}//如果有Classpath下面有 com.google.gson.Gson，则添加//GsonHttpMessageConverter的BeanDefinitionelse if (gsonPresent) {messageConverters.add(createConverterDefinition(GsonHttpMessageConverter.class, source));}}return messageConverters;}

上面的这段内容主要是添加一些自己配置的HttpMessageConverter的BeanDefinition或者是一些初始化的HttpMessageConverter的BeanDefinition

ManagedList<?> argumentResolvers = getArgumentResolvers(element, parserContext);

这一段的内容主要是获取自定义的一些参数解析器(HandlerMethodArgumentResolver的实现类)

ManagedList<?> returnValueHandlers = getReturnValueHandlers(element, parserContext);

这一段是配置自定义的HandlerMethodReturnValueHandler的实现类，没什么可说的。标签如下：

        <mvc:return-value-handlers>        </mvc:return-value-handlers>

String asyncTimeout = getAsyncTimeout(element);RuntimeBeanReference asyncExecutor = getAsyncExecutor(element);ManagedList<?> callableInterceptors = getCallableInterceptors(element, source, parserContext);ManagedList<?> deferredResultInterceptors = getDeferredResultInterceptors(element, source, parserContext);

上面这一段是配置异步的请求处理信息。

RootBeanDefinition handlerAdapterDef = new RootBeanDefinition(RequestMappingHandlerAdapter.class);handlerAdapterDef.setSource(source);handlerAdapterDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);handlerAdapterDef.getPropertyValues().add("contentNegotiationManager", contentNegotiationManager);handlerAdapterDef.getPropertyValues().add("webBindingInitializer", bindingDef);handlerAdapterDef.getPropertyValues().add("messageConverters", messageConverters);

上面这一段是创建RequestMappingHandlerAdapter的BeanDefinition。并给webBindingInitializer属性和messageConverters属性赋值，赋值的内容是前面获取的的Bean对象。

addRequestBodyAdvice(handlerAdapterDef);

protected void addRequestBodyAdvice(RootBeanDefinition beanDef) {//如果Classpath下面有com.fasterxml.jackson.databind.ObjectMapper和//com.fasterxml.jackson.core.JsonGenerator这两个类的话，则添加JsonViewRequestBodyAdvice到//requestResponseBodyAdvice集合中if (jackson2Present) {beanDef.getPropertyValues().add("requestBodyAdvice",new RootBeanDefinition(JsonViewRequestBodyAdvice.class));}}

上面的这段代码中是给RequestHandlerMappingAdapter的requestResponseBodyAdvice属性中添加值。

addResponseBodyAdvice(handlerAdapterDef);

protected void addResponseBodyAdvice(RootBeanDefinition beanDef) {//如果Classpath下面有com.fasterxml.jackson.databind.ObjectMapper和//com.fasterxml.jackson.core.JsonGenerator这两个类的话，则添加JsonViewResponseBodyAdvice到//requestResponseBodyAdvice集合中if (jackson2Present) {beanDef.getPropertyValues().add("responseBodyAdvice",new RootBeanDefinition(JsonViewResponseBodyAdvice.class));}}

-上面的这段代码中是给RequestHandlerMappingAdapter的requestResponseBodyAdvice属性中添加值。

if (argumentResolvers != null) {handlerAdapterDef.getPropertyValues().add("customArgumentResolvers", argumentResolvers);}if (returnValueHandlers != null) {handlerAdapterDef.getPropertyValues().add("customReturnValueHandlers", returnValueHandlers);}

给RequestHandlerMappingAdapter中的customArgumentResolvers添加自定义的参数解析器。给RequestHandlerMappingAdapter中的customReturnValueHandlers添加自定义的参数返回处理器。

readerContext.getRegistry().registerBeanDefinition(HANDLER_ADAPTER_BEAN_NAME , handlerAdapterDef);

将创建的RequestMappingHandlerAdapter注册到IOC容器中。bean的name为org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter。

在AnnotationDrivenBeanDefinitionParser中还添加了其他的一些Bean到IOC容器中，下面我们挑一些我们熟悉的说一下：

RootBeanDefinition exceptionHandlerExceptionResolver = new RootBeanDefinition(ExceptionHandlerExceptionResolver.class);exceptionHandlerExceptionResolver.setSource(source);exceptionHandlerExceptionResolver.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);exceptionHandlerExceptionResolver.getPropertyValues().add("contentNegotiationManager", contentNegotiationManager);exceptionHandlerExceptionResolver.getPropertyValues().add("messageConverters", messageConverters);exceptionHandlerExceptionResolver.getPropertyValues().add("order", 0);addResponseBodyAdvice(exceptionHandlerExceptionResolver);if (argumentResolvers != null) {exceptionHandlerExceptionResolver.getPropertyValues().add("customArgumentResolvers", argumentResolvers);}if (returnValueHandlers != null) {exceptionHandlerExceptionResolver.getPropertyValues().add("customReturnValueHandlers", returnValueHandlers);}

添加ExceptionHandlerExceptionResolver，处理异常信息的。

RootBeanDefinition responseStatusExceptionResolver = new RootBeanDefinition(ResponseStatusExceptionResolver.class);responseStatusExceptionResolver.setSource(source);responseStatusExceptionResolver.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);responseStatusExceptionResolver.getPropertyValues().add("order", 1);String responseStatusExceptionResolverName =readerContext.registerWithGeneratedName(responseStatusExceptionResolver);

异常信息的另外一种处理方式，将异常信息映射为HTTP状态码。

RootBeanDefinition defaultExceptionResolver = new RootBeanDefinition(DefaultHandlerExceptionResolver.class);defaultExceptionResolver.setSource(source);defaultExceptionResolver.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);defaultExceptionResolver.getPropertyValues().add("order", 2);String defaultExceptionResolverName =readerContext.registerWithGeneratedName(defaultExceptionResolver);

默认的异常信息解析器。这三个异常信息解析器的处理顺序是：ExceptionHandlerExceptionResolver最先，ResponseStatusExceptionResolver次之，DefaultHandlerExceptionResolver顺序为最后。

MvcNamespaceUtils.registerDefaultComponents(parserContext, source);

这这一段代码总主要是添加默认的几个Bean，分别是：BeanNameUrlHandlerMapping、HttpRequestHandlerAdapter、SimpleControllerHandlerAdapter。