springMVC源码分析--AbstractHandlerMethodMapping注册url和HandlerMethod对应关系（十一）

一时失言乱红尘 2022-07-13 03:08 117阅读 0赞

在上一篇博客[springMVC源码分析--AbstractHandlerMethodMapping获取url和HandlerMethod对应关系（十）][springMVC_--AbstractHandlerMethodMapping_url_HandlerMethod]中我们简单地介绍了获取url和HandlerMethod的过程，接下来我介绍一些url和HandlerMethod对应关系的注册过程。

![Image 1][]

在AbstractHandlerMethodMapping中当bean被注入到容器后会执行一系列的初始化过程，代码如下：

//容器启动时会运行此方法，完成handlerMethod的注册操作
    	@Override
    	public void afterPropertiesSet() {
    		initHandlerMethods();
    	}

进行HandlerMethod的注册操作，简单来说就是从springMVC的容器中获取所有的beanName，注册url和实现方法HandlerMethod的对应关系。

//handlerMethod的注册操作
    	protected void initHandlerMethods() {
    		if (logger.isDebugEnabled()) {
    			logger.debug("Looking for request mappings in application context: " + getApplicationContext());
    		}
    		//从springMVC容器中获取所有的beanName
    		String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ?
    				BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) :
    				getApplicationContext().getBeanNamesForType(Object.class));
     //注册从容器中获取的beanName
    		for (String name : beanNames) {
    			if (!name.startsWith(SCOPED_TARGET_NAME_PREFIX) && isHandler(getApplicationContext().getType(name))) {
    				detectHandlerMethods(name);
    			}
    		}
    		handlerMethodsInitialized(getHandlerMethods());
    	}

根据beanName进行一系列的注册，最终实现是在registerHandlerMethod

protected void detectHandlerMethods(final Object handler) {
    		//获取bean实例
    		Class<?> handlerType =
    				(handler instanceof String ? getApplicationContext().getType((String) handler) : handler.getClass());
    
    		// Avoid repeated calls to getMappingForMethod which would rebuild RequestMappingInfo instances
    		final Map<Method, T> mappings = new IdentityHashMap<Method, T>();
    		final Class<?> userType = ClassUtils.getUserClass(handlerType);
    
    		Set<Method> methods = HandlerMethodSelector.selectMethods(userType, new MethodFilter() {
    			@Override
    			public boolean matches(Method method) {
    				//创建RequestMappingInfo
    				T mapping = getMappingForMethod(method, userType);
    				if (mapping != null) {
    					mappings.put(method, mapping);
    					return true;
    				}
    				else {
    					return false;
    				}
    			}
    		});
    	
    		for (Method method : methods) {
    			registerHandlerMethod(handler, method, mappings.get(method));
    		}
    	}

registerHandlerMethod的注册操作是将beanName，Method及创建的RequestMappingInfo之间的 关系。

//注册beanName和method及RequestMappingInfo之间的关系，RequestMappingInfo会保存url信息
    	@Deprecated
    	protected void registerHandlerMethod(Object handler, Method method, T mapping) {
    		this.mappingRegistry.register(mapping, handler, method);
    	}

getMappingForMethod方法是在子类RequestMappingHandlerMapping中实现的，具体实现就是创建一个RequestMappingInfo

@Override
    	protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
    		RequestMappingInfo info = createRequestMappingInfo(method);
    		if (info != null) {
    			RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType);
    			if (typeInfo != null) {
    				info = typeInfo.combine(info);
    			}
    		}
    		return info;
    	}
    
    	private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {
    		RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping.class);
    		RequestCondition<?> condition = (element instanceof Class<?> ?
    				getCustomTypeCondition((Class<?>) element) : getCustomMethodCondition((Method) element));
    		return (requestMapping != null ? createRequestMappingInfo(requestMapping, condition) : null);
    	}

这样就简单实现了将url和HandlerMethod的对应关系注册到mappingRegistry中。

MappingRegistry中的注册实现如下，并且MappingRegistry定义了几个map结构，用来存储注册信息

private final Map<T, MappingRegistration<T>> registry = new HashMap<T, MappingRegistration<T>>();
    
    		private final Map<T, HandlerMethod> mappingLookup = new LinkedHashMap<T, HandlerMethod>();
    
    		private final MultiValueMap<String, T> urlLookup = new LinkedMultiValueMap<String, T>();
    
    		private final Map<String, List<HandlerMethod>> nameLookup =
    				new ConcurrentHashMap<String, List<HandlerMethod>>();
    
    		private final Map<HandlerMethod, CorsConfiguration> corsLookup =
    				new ConcurrentHashMap<HandlerMethod, CorsConfiguration>();

完成beanName，HandlerMethod及RequestMappingInfo之间的对应关系注册。

//注册beanName和method及RequestMappingInfo之间的关系，RequestMappingInfo中有url信息
    		public void register(T mapping, Object handler, Method method) {
    
    			this.readWriteLock.writeLock().lock();
    			try {
    				//创建HandlerMethod
    				HandlerMethod handlerMethod = createHandlerMethod(handler, method);
    				assertUniqueMethodMapping(handlerMethod, mapping);
    
    				if (logger.isInfoEnabled()) {
    					logger.info("Mapped \"" + mapping + "\" onto " + handlerMethod);
    				}
    				//保存url和handlerMethod之间的对应关系
    				this.mappingLookup.put(mapping, handlerMethod);
    				//保存url和RequestMappingInfo对应关系
    				List<String> directUrls = getDirectUrls(mapping);
    				for (String url : directUrls) {
    					this.urlLookup.add(url, mapping);
    				}
    
    				String name = null;
    				if (getNamingStrategy() != null) {
    					name = getNamingStrategy().getName(handlerMethod, mapping);
    					addMappingName(name, handlerMethod);
    				}
    
    				CorsConfiguration corsConfig = initCorsConfiguration(handler, method, mapping);
    				if (corsConfig != null) {
    					this.corsLookup.put(handlerMethod, corsConfig);
    				}
    
    				this.registry.put(mapping, new MappingRegistration<T>(mapping, handlerMethod, directUrls, name));
    			}
    			finally {
    				this.readWriteLock.writeLock().unlock();
    			}
    		}

[springMVC_--AbstractHandlerMethodMapping_url_HandlerMethod]: http://blog.csdn.net/qq924862077/article/details/53787699
[Image 1]: