springMVC源码分析--AbstractHandlerMapping（二）

上一篇博客 springMVC源码分析--HandlerMapping(一)中我们简单的介绍了HandlerMapping，接下来我们介绍一下它的抽象实现类AbstractHandlerMapping

HandlerMapping中定义了方法getHandler（HttpServletRequest request），AbstractHandlerMapping中的实现如下：

//获得一个HandlerExecutionChain
	@Override
	public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
		//从实现类中获得HanlderMethod
		Object handler = getHandlerInternal(request);
		if (handler == null) {
			handler = getDefaultHandler();
		}
		if (handler == null) {
			return null;
		}
		// Bean name or resolved handler?
		if (handler instanceof String) {
			String handlerName = (String) handler;
			handler = getApplicationContext().getBean(handlerName);
		}
		//获得HandlerExecutionChain
		HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request);
		if (CorsUtils.isCorsRequest(request)) {
			CorsConfiguration globalConfig = this.corsConfigSource.getCorsConfiguration(request);
			CorsConfiguration handlerConfig = getCorsConfiguration(handler, request);
			CorsConfiguration config = (globalConfig != null ? globalConfig.combine(handlerConfig) : handlerConfig);
			executionChain = getCorsHandlerExecutionChain(request, executionChain, config);
		}
		return executionChain;
	}

在getHandler方法中又出现了两个方法getHandlerInternal（request），在子类中实现，目的就是获取要执行的Controller。

//模板方法，用于子类中实现，通过request去查找对应的执行方法HandlerMethod
	protected abstract Object getHandlerInternal(HttpServletRequest request) throws Exception;

getHandlerExecutionChain就是创建一个HandlerExecutionChain实例，参数值就是handler和request。

//
	protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {
		//如果没有获得则创建一个
		HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?
				(HandlerExecutionChain) handler : new HandlerExecutionChain(handler));
		//获得IP地址及端口后的URL地址
		String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);
		//在HandlerExecutionChain中添加拦截器
		for (HandlerInterceptor interceptor : this.adaptedInterceptors) {
			if (interceptor instanceof MappedInterceptor) {
				MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor;
				//根据lookupPath来获取Interceptor
				if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {
					chain.addInterceptor(mappedInterceptor.getInterceptor());
				}
			}
			else {
				chain.addInterceptor(interceptor);
			}
		}
		return chain;
	}

AbstractHandlerMapping提供了设置不同HandlerMapping的执行顺序oder。

//设置不同HandlerMapping实现类的执行顺序
	public final void setOrder(int order) {
	  this.order = order;
	}

	@Override
	public final int getOrder() {
	  return this.order;
	}

除了以上几个重要的方法外，AbstractHandlerMapping还提供了进行拦截器初始化的一些操作。

//初始化时调用，初始化一些基本信息，这里主要是初始化一些拦截器
	@Override
	protected void initApplicationContext() throws BeansException {
		extendInterceptors(this.interceptors);//添加或修车intercept，现在并没有具体实现
		detectMappedInterceptors(this.adaptedInterceptors);//将springMVC容器或者父容器中的所有MappedInterceptor类型的Bean添加到mappedInterceptors属性中
		initInterceptors();
	}

	protected void extendInterceptors(List