接着上篇的 第一个点分析

getHandler

 mappedHandler = this.getHandler(processedRequest);

 @Nullable
    protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
        if (this.handlerMappings != null) {
            Iterator var2 = this.handlerMappings.iterator();

            while(var2.hasNext()) {
                HandlerMapping mapping = (HandlerMapping)var2.next();
                HandlerExecutionChain handler = mapping.getHandler(request);
                if (handler != null) {
                    return handler;
                }
            }
        }

        return null;
    }

从源码中可以看出 从一个HandlerMapping列表中获取到一个不为空的HandlerExecutionChain就返回

其中handlerMappings是个list

@Nullable
    private List<HandlerMapping> handlerMappings;

看看HandlerMapping和HandlerExecutionChain是个什么东东

1. HandlerMapping

是一个接口，只有一个返回HandlerExecutionChain的方法

public interface HandlerMapping {
    String BEST_MATCHING_HANDLER_ATTRIBUTE = HandlerMapping.class.getName() + ".bestMatchingHandler";
    String PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE = HandlerMapping.class.getName() + ".pathWithinHandlerMapping";
    String BEST_MATCHING_PATTERN_ATTRIBUTE = HandlerMapping.class.getName() + ".bestMatchingPattern";
    String INTROSPECT_TYPE_LEVEL_MAPPING = HandlerMapping.class.getName() + ".introspectTypeLevelMapping";
    String URI_TEMPLATE_VARIABLES_ATTRIBUTE = HandlerMapping.class.getName() + ".uriTemplateVariables";
    String MATRIX_VARIABLES_ATTRIBUTE = HandlerMapping.class.getName() + ".matrixVariables";
    String PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE = HandlerMapping.class.getName() + ".producibleMediaTypes";

    @Nullable
    HandlerExecutionChain getHandler(HttpServletRequest var1) throws Exception;
}

2.HandlerExecutionChain

2.1 属性

 private final Object handler;
    @Nullable
    private HandlerInterceptor[] interceptors;
    @Nullable
    private List<HandlerInterceptor> interceptorList;
    private int interceptorIndex;

• handler：具体执行方法
• HandlerInterceptor：拦截器

2.2 主要方法

• applyPreHandle

boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
        HandlerInterceptor[] interceptors = this.getInterceptors();
        if (!ObjectUtils.isEmpty(interceptors)) {
            for(int i = 0; i < interceptors.length; this.interceptorIndex = i++) {
                HandlerInterceptor interceptor = interceptors[i];
                if (!interceptor.preHandle(request, response, this.handler)) {
                    this.triggerAfterCompletion(request, response, (Exception)null);
                    return false;
                }
            }
        }

        return true;
    }

执行了拦截器的preHandle方法
下面基本思路相同

• applyPostHandle

 void applyPostHandle(HttpServletRequest request, HttpServletResponse response, @Nullable ModelAndView mv) throws Exception {
        HandlerInterceptor[] interceptors = this.getInterceptors();
        if (!ObjectUtils.isEmpty(interceptors)) {
            for(int i = interceptors.length - 1; i >= 0; --i) {
                HandlerInterceptor interceptor = interceptors[i];
                interceptor.postHandle(request, response, this.handler, mv);
            }
        }

    }

• triggerAfterCompletion

void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, @Nullable Exception ex) throws Exception {
        HandlerInterceptor[] interceptors = this.getInterceptors();
        if (!ObjectUtils.isEmpty(interceptors)) {
            for(int i = this.interceptorIndex; i >= 0; --i) {
                HandlerInterceptor interceptor = interceptors[i];

                try {
                    interceptor.afterCompletion(request, response, this.handler, ex);
                } catch (Throwable var8) {
                    logger.error("HandlerInterceptor.afterCompletion threw exception", var8);
                }
            }
        }

    }

• applyAfterConcurrentHandlingStarted

    void applyAfterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response) {
        HandlerInterceptor[] interceptors = this.getInterceptors();
        if (!ObjectUtils.isEmpty(interceptors)) {
            for(int i = interceptors.length - 1; i >= 0; --i) {
                if (interceptors[i] instanceof AsyncHandlerInterceptor) {
                    try {
                        AsyncHandlerInterceptor asyncInterceptor = (AsyncHandlerInterceptor)interceptors[i];
                        asyncInterceptor.afterConcurrentHandlingStarted(request, response, this.handler);
                    } catch (Throwable var6) {
                        logger.error("Interceptor [" + interceptors[i] + "] failed in afterConcurrentHandlingStarted", var6);
                    }
                }
            }
        }

    }

看到这里就必须知道handlerMappings怎么初始化的，怎么和controller绑定，怎么和拦截器绑定，怎么查找的 初始化过程会详细描述