//RequestMappingHandlerMapping
@Override
  public void afterPropertiesSet() {
    this.config = new RequestMappingInfo.BuilderConfiguration();
    this.config.setUrlPathHelper(getUrlPathHelper());
    this.config.setPathMatcher(getPathMatcher());
    this.config.setSuffixPatternMatch(this.useSuffixPatternMatch);
    this.config.setTrailingSlashMatch(this.useTrailingSlashMatch);
    this.config.setRegisteredSuffixPatternMatch(this.useRegisteredSuffixPatternMatch);
    this.config.setContentNegotiationManager(getContentNegotiationManager());
        //调用父类的方法，跟进去--->
    super.afterPropertiesSet();
  }

//AbstractHandlerMethodMapping
protected void initHandlerMethods() {
        //遍历所有的类
    for (String beanName : getCandidateBeanNames()) {
      if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) {
                //当beanName为自定义的helloController时跟进去--->
        processCandidateBean(beanName);
      }
    }
    handlerMethodsInitialized(getHandlerMethods());
  }

//AbstractHandlerMethodMapping
protected void processCandidateBean(String beanName) {
    Class<?> beanType = null;
    try {
      beanType = obtainApplicationContext().getType(beanName);
    }
    catch (Throwable ex) {
      // An unresolvable bean type, probably from a lazy bean - let's ignore it.
      if (logger.isTraceEnabled()) {
        logger.trace("Could not resolve type for bean '" + beanName + "'", ex);
      }
    }
        //如果此类上有Controller或者RequestMapping，则返回真
    if (beanType != null && isHandler(beanType)) {
            //跟进去--->
      detectHandlerMethods(beanName);
    }

AbstractHandlerMethodMapping
protected void detectHandlerMethods(Object handler) {
    Class<?> handlerType = (handler instanceof String ?
        obtainApplicationContext().getType((String) handler) : handler.getClass());
    if (handlerType != null) {
      Class<?> userType = ClassUtils.getUserClass(handlerType);
            //解析类并且获取所有带有requestMapping的方法
      Map<Method, T> methods = MethodIntrospector.selectMethods(userType,
          (MethodIntrospector.MetadataLookup<T>) method -> {
            try {
              return getMappingForMethod(method, userType);
            }
            catch (Throwable ex) {
              throw new IllegalStateException("Invalid mapping on handler class [" +
                  userType.getName() + "]: " + method, ex);
            }
          });
      if (logger.isTraceEnabled()) {
        logger.trace(formatMappings(userType, methods));
      }
            //此时将method和mapping都注入到某个地方(map)中，后面就可以直接使用了
      methods.forEach((method, mapping) -> {
        Method invocableMethod = AopUtils.selectInvocableMethod(method, userType);
        registerHandlerMethod(handler, invocableMethod, mapping);
      });
    }
  }