SpringMVC源码情操陶冶-AnnotationDrivenBeanDefinitionParser注解解析器
mvc:annotation-driven节点的解析器，是springmvc的核心解析器
官方注释
Open Declaration org.springframework.web.servlet.config.AnnotationDrivenBeanDefinitionParser
A BeanDefinitionParser that provides the configuration for the <annotation-driven/> MVC namespace element.
This class registers the following <<HandlerMappings>>:
•RequestMappingHandlerMapping ordered at 0 for mapping requests to annotated controller methods.
•BeanNameUrlHandlerMapping ordered at 2 to map URL paths to controller bean names.
Note: Additional HandlerMappings may be registered as a result of using the <view-controller> or the <resources> MVC namespace elements.
This class registers the following <<HandlerAdapters>>:
•RequestMappingHandlerAdapter for processing requests with annotated controller methods.
•HttpRequestHandlerAdapter for processing requests with HttpRequestHandlers.
•SimpleControllerHandlerAdapter for processing requests with interface-based Controllers.
This class registers the following <<HandlerExceptionResolvers>>:
•ExceptionHandlerExceptionResolver for handling exceptions through @ExceptionHandler methods.
•ResponseStatusExceptionResolver for exceptions annotated with @ResponseStatus.
•DefaultHandlerExceptionResolver for resolving known Spring exception types
This class registers an org.springframework.util.<<AntPathMatcher>> and a org.springframework.web.util.<<UrlPathHelper>> to be used by:
•the RequestMappingHandlerMapping,
•the HandlerMapping for ViewControllers
•and the HandlerMapping for serving resources
Note that those beans can be configured by using the path-matching MVC namespace element.
Both the RequestMappingHandlerAdapter and the ExceptionHandlerExceptionResolver are configured with instances of the following by default:
•A ContentNegotiationManager
•A DefaultFormattingConversionService
•A org.springframework.validation.beanvalidation.LocalValidatorFactoryBean if a JSR-303 implementation is available on the classpath
•A range of HttpMessageConverters depending on what 3rd party libraries are available on the classpath.
主要注册HandlerMappings-路径匹配器、HandlerAdapters-路径匹配适配器、HandlerExceptionResolvers-异常解析器、AntPathMatcher-路径解析器、UrlPathHelper-请求路径获取帮助类等beans，提前为mvc做好基础的准备
AnnotationDrivenBeanDefinitionParser#parse
从此方法中，提炼实现的最主要代码片段，代码如下
parserContext.registerComponent(new BeanComponentDefinition(handlerMappingDef, HANDLER_MAPPING_BEAN_NAME));
parserContext.registerComponent(new BeanComponentDefinition(handlerAdapterDef, HANDLER_ADAPTER_BEAN_NAME));
parserContext.registerComponent(new BeanComponentDefinition(uriCompContribDef, uriCompContribName));
parserContext.registerComponent(new BeanComponentDefinition(exceptionHandlerExceptionResolver, methodExceptionResolverName));
parserContext.registerComponent(new BeanComponentDefinition(responseStatusExceptionResolver, responseStatusExceptionResolverName));
parserContext.registerComponent(new BeanComponentDefinition(defaultExceptionResolver, defaultExceptionResolverName));
//格式转换处理拦截类，比如时间、数字等
parserContext.registerComponent(new BeanComponentDefinition(mappedCsInterceptorDef, mappedInterceptorName));
// Ensure BeanNameUrlHandlerMapping (SPR-8289) and default HandlerAdapters are not "turned off"
MvcNamespaceUtils.registerDefaultComponents(parserContext, source);
跟官方注释提及的一样，主要目的是注册与mvc处理有关的相关beans以及默认的mvc组件，下面我们将从以上代码的不同组件生成进行逐个分析
HandlerMappings组件注册
对应parse()方法的代码片段如下
//生成RequestMappingHandlerMapping组件对象
RootBeanDefinition handlerMappingDef = new RootBeanDefinition(RequestMappingHandlerMapping.class);
handlerMappingDef.setSource(source);
handlerMappingDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
//优先级设置为最高
handlerMappingDef.getPropertyValues().add("order", 0);
//添加contentNegotiationManager属性，处理media type handlerMappingDef.getPropertyValues().add("contentNegotiationManager", contentNegotiationManager);
//查看mvc:annotation-driven有无enable-matrix-variables/enableMatrixVariables，表示是否开启多变量映射比如/cars;a=1;b=1
//具体使用可查阅相关文档，默认removeSemicolonContent为false
if (element.hasAttribute("enable-matrix-variables")) {
Boolean enableMatrixVariables = Boolean.valueOf(element.getAttribute("enable-matrix-variables"));
handlerMappingDef.getPropertyValues().add("removeSemicolonContent", !enableMatrixVariables);
}
else if (element.hasAttribute("enableMatrixVariables")) {
Boolean enableMatrixVariables = Boolean.valueOf(element.getAttribute("enableMatrixVariables"));
handlerMappingDef.getPropertyValues().add("removeSemicolonContent", !enableMatrixVariables);
}
//配置路径匹配解析器等属性
configurePathMatchingProperties(handlerMappingDef, element, parserContext);
//将RequestMappingHandlerMapping注册为bean对象放置bean工厂中 readerContext.getRegistry().registerBeanDefinition(HANDLER_MAPPING_BEAN_NAME , handlerMappingDef);
RequestMappingHandlerMapping主要是处理@Controller和@RequestMapping注解的，另外再看下configurePathMatchingProperties()配置路径解析器方法
AnnotationDrivenBeanDefinitionParser#configurePathMatchingProperties-路径匹配解析器配置
代码如下
private void configurePathMatchingProperties(RootBeanDefinition handlerMappingDef, Element element,
ParserContext parserContext) {
//获取mvc:annotation-driven下子节点mvc:path-matching
Element pathMatchingElement = DomUtils.getChildElementByTagName(element, "path-matching");
if (pathMatchingElement != null) {
Object source = parserContext.extractSource(element);
//是否采用suffix-pattern，即.*,比如/user也匹配/user.*。默认为true
if (pathMatchingElement.hasAttribute("suffix-pattern")) {
Boolean useSuffixPatternMatch = Boolean.valueOf(pathMatchingElement.getAttribute("suffix-pattern"));
handlerMappingDef.getPropertyValues().add("useSuffixPatternMatch", useSuffixPatternMatch);
}
//是否采用分隔符，特指/，比如/user也匹配/user/。默认为true
if (pathMatchingElement.hasAttribute("trailing-slash")) {
Boolean useTrailingSlashMatch = Boolean.valueOf(pathMatchingElement.getAttribute("trailing-slash"));
handlerMappingDef.getPropertyValues().add("useTrailingSlashMatch", useTrailingSlashMatch);
}
//是否采用contentNegotiationManager中的格式，比如*.json/*.xml。默认为false
if (pathMatchingElement.hasAttribute("registered-suffixes-only")) {
Boolean useRegisteredSuffixPatternMatch = Boolean.valueOf(pathMatchingElement.getAttribute("registered-suffixes-only"));
handlerMappingDef.getPropertyValues().add("useRegisteredSuffixPatternMatch", useRegisteredSuffixPatternMatch);
}
RuntimeBeanReference pathHelperRef = null;
//路径解析帮助类，可指定，默认为UrlPathHelper
if (pathMatchingElement.hasAttribute("path-helper")) {
pathHelperRef = new RuntimeBeanReference(pathMatchingElement.getAttribute("path-helper"));
}
pathHelperRef = MvcNamespaceUtils.registerUrlPathHelper(pathHelperRef, parserContext, source);
handlerMappingDef.getPropertyValues().add("urlPathHelper", pathHelperRef);
RuntimeBeanReference pathMatcherRef = null;
//路径解析器，默认为AntPathMatcher解析器
if (pathMatchingElement.hasAttribute("path-matcher")) {
pathMatcherRef = new RuntimeBeanReference(pathMatchingElement.getAttribute("path-matcher"));
}
pathMatcherRef = MvcNamespaceUtils.registerPathMatcher(pathMatcherRef, parserContext, source);
handlerMappingDef.getPropertyValues().add("pathMatcher", pathMatcherRef);
}
}
看代码逻辑，主要是通过mvc:annotation-driven下的mvc:path-matching节点来配置
- suffix-pattern-是否启用后缀匹配，默认为true，即对指定的url会再新增
.*，比如/user实际匹配/user.*->/user匹配/user.html,/user.jsp- trailing-slash-是否启动尾部斜线匹配，默认为true，即对指定的url会新增
/，比如/user也会匹配/user/- registered-suffixes-only-是否启用media type类型的匹配，即对指定的url新增
*.json/*.xml等匹配，默认为false- path-helper-路径获取帮助类，默认为UrlPathHelper类
- path-matcher-路径匹配解析器，默认为AntPathMather
HandlerAdapters组件注册
相应的代码片段如下
//获取conversion-service属性，默认为FormattingConversionServiceFactoryBean
//处理一些基本类的格式与转换，比如时间、数字等
RuntimeBeanReference conversionService = getConversionService(element, source, parserContext);
//获取validator,默认为OptionalValidatorFactoryBean，基于java自带的Validator接口，表示校验器，可用于javabean的参数校验等
RuntimeBeanReference validator = getValidator(element, source, parserContext);
//获取message-codes-resolver属性，默认为null。
RuntimeBeanReference messageCodesResolver = getMessageCodesResolver(element);
//设置ConfigurableWebBindingInitializer类 用于数据绑定
RootBeanDefinition bindingDef = new RootBeanDefinition(ConfigurableWebBindingInitializer.class);
bindingDef.setSource(source);
bindingDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
bindingDef.getPropertyValues().add("conversionService", conversionService);
bindingDef.getPropertyValues().add("validator", validator);
bindingDef.getPropertyValues().add("messageCodesResolver", messageCodesResolver);
//获取message-converters子节点的配置，消息转换器，可用于向前端发送数据再次自定义组装
//比如MappingJackson2HttpMessageConverter json转字符串
ManagedList<?> messageConverters = getMessageConverters(element, source, parserContext);
//argument-resolvers子节点配置，参数解析
ManagedList<?> argumentResolvers = getArgumentResolvers(element, parserContext);
//return-value-handlers子节点解析
ManagedList<?> returnValueHandlers = getReturnValueHandlers(element, parserContext);
//async-support子节点解析，获取其中的default-timeout属性，作为异步处理超时时间，默认null
String asyncTimeout = getAsyncTimeout(element);
//async-support子节点解析，获取其中的task-executor属性。异步任务线程池
RuntimeBeanReference asyncExecutor = getAsyncExecutor(element);
//async-support子节点解析，获取其中的callable-interceptors节点。异步处理callable类型拦截器
ManagedList<?> callableInterceptors = getCallableInterceptors(element, source, parserContext);
ManagedList<?> deferredResultInterceptors = getDeferredResultInterceptors(element, source, parserContext);
//将上述的属性添加到RequestMappingHandlerAdapter中
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);
addRequestBodyAdvice(handlerAdapterDef);
addResponseBodyAdvice(handlerAdapterDef);
//ignoreDefaultModelOnRedirect属性配置
if (element.hasAttribute("ignore-default-model-on-redirect")) {
Boolean ignoreDefaultModel = Boolean.valueOf(element.getAttribute("ignore-default-model-on-redirect"));
handlerAdapterDef.getPropertyValues().add("ignoreDefaultModelOnRedirect", ignoreDefaultModel);
}
else if (element.hasAttribute("ignoreDefaultModelOnRedirect")) {
// "ignoreDefaultModelOnRedirect" spelling is deprecated
Boolean ignoreDefaultModel = Boolean.valueOf(element.getAttribute("ignoreDefaultModelOnRedirect"));
handlerAdapterDef.getPropertyValues().add("ignoreDefaultModelOnRedirect", ignoreDefaultModel);
}
if (argumentResolvers != null) {
handlerAdapterDef.getPropertyValues().add("customArgumentResolvers", argumentResolvers);
}
if (returnValueHandlers != null) {
handlerAdapterDef.getPropertyValues().add("customReturnValueHandlers", returnValueHandlers);
}
if (asyncTimeout != null) {
handlerAdapterDef.getPropertyValues().add("asyncRequestTimeout", asyncTimeout);
}
if (asyncExecutor != null) {
handlerAdapterDef.getPropertyValues().add("taskExecutor", asyncExecutor);
}
handlerAdapterDef.getPropertyValues().add("callableInterceptors", callableInterceptors);
handlerAdapterDef.getPropertyValues().add("deferredResultInterceptors", deferredResultInterceptors);
readerContext.getRegistry().registerBeanDefinition(HANDLER_ADAPTER_BEAN_NAME , handlerAdapterDef);
配置的主要是
RequestMappingHandlerAdapter对象，其中的属性较多，读者可查看>>>SpringMVC源码情操陶冶-RequestMappingHandlerAdapter适配器。其主要支持HandlerMethod类，而这些类都是由RequestMappingHandlerMapping来生成的，而这又是通过AbstractHandlerMethodMapping#initHandlerMethods来实现的，有兴趣的可以自行去查阅
ExceptionResolver组件注册
默认采用ExceptionHandlerExceptionResolver、ResponseStatusExceptionResolver、DefaultHandlerExceptionResolver作为异常处理类
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);
String methodExceptionResolverName = readerContext.registerWithGeneratedName(exceptionHandlerExceptionResolver);
RootBeanDefinition responseStatusExceptionResolver = new RootBeanDefinition(ResponseStatusExceptionResolver.class);
responseStatusExceptionResolver.setSource(source);
responseStatusExceptionResolver.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
responseStatusExceptionResolver.getPropertyValues().add("order", 1);
String responseStatusExceptionResolverName =
readerContext.registerWithGeneratedName(responseStatusExceptionResolver);
RootBeanDefinition defaultExceptionResolver = new RootBeanDefinition(DefaultHandlerExceptionResolver.class);
defaultExceptionResolver.setSource(source);
defaultExceptionResolver.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
defaultExceptionResolver.getPropertyValues().add("order", 2);
String defaultExceptionResolverName =
readerContext.registerWithGeneratedName(defaultExceptionResolver);
ExceptionHandlerExceptionResolver-处理
@ExceptionHandler方法注解ResponseStatusExceptionResolver-处理
@ResponseStatus类型、方法注解DefaultHandlerExceptionResolver-处理普通的spring异常
更准确的可查看官方注释说明
小结
mvc:annotation-driven一句话便囊括了springmvc的基本处理组件注册成bean到springmvc上下文，结合此处再去理解springmvc的逻辑源码就简单了
作者：南柯问天
出处：http://www.cnblogs.com/question-sky/
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