<input type="button" value="测试JSON数据" onclick="testJSON()" /> 
<script type="text/javascript"> 
  function testJSON() { 
    $.ajax({ 
      type: "POST", 
      url: "/testJson", 
      contentType: "application/json", 
      dataType: "json", 
      data: JSON.stringify({"name":"张三"}), 
      success: function (jsonResult) { 
        alert(jsonResult); 
      } 
    }); 
  } 
</script> 

@RequestMapping(value ="testJson") 
public String testJson(@RequestBody Map name, HttpServletRequest request){ 
  System.out.println(name); 
  return "jsonp"; 
} 

Content-Type:application/json 

mv = ha.handle(processedRequest, response, mappedHandler.getHandler()); 

public final ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) 
    throws Exception { 
 
  return handleInternal(request, response, (HandlerMethod) handler); 
} 

@Override 
protected ModelAndView handleInternal(HttpServletRequest request, 
    HttpServletResponse response, HandlerMethod handlerMethod) throws Exception { 
 
  ModelAndView mav; 
  checkRequest(request);//检查是不是所支持的请求类型、是不是要求session 
 
  // Execute invokeHandlerMethod in synchronized block if required. 
  if (this.synchronizeOnSession) {//session中是不是要求同步执行 
    HttpSession session = request.getSession(false); 
    if (session != null) { 
      Object mutex = WebUtils.getSessionMutex(session); 
      synchronized (mutex) {//同步执行方法调用 
        mav = invokeHandlerMethod(request, response, handlerMethod); 
      } 
    } 
    else { 
      // No HttpSession available -> no mutex necessary 
      mav = invokeHandlerMethod(request, response, handlerMethod); 
    } 
  } 
  else { 
    // No synchronization on session demanded at all... 
    mav = invokeHandlerMethod(request, response, handlerMethod);//这三个invokeHandlerMethod调用的是同一个方法 
  }//缓存的设置 
  if (!response.containsHeader(HEADER_CACHE_CONTROL)) { 
    if (getSessionAttributesHandler(handlerMethod).hasSessionAttributes()) { 
      applyCacheSeconds(response, this.cacheSecondsForSessionAttributeHandlers); 
    } 
    else { 
      prepareResponse(response); 
    } 
  } 
 
  return mav; 
} 

invocableMethod.invokeAndHandle(webRequest, mavContainer); 

Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs); 

Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs); 

  private Object[] getMethodArgumentValues(NativeWebRequest request, ModelAndViewContainer mavContainer, 
      Object... providedArgs) throws Exception { 
//获取参数对象数组 方法中的参数都在这个对象数组中存放着。 
    MethodParameter[] parameters = getMethodParameters(); 
    Object[] args = new Object[parameters.length]; 
    for (int i = 0; i < parameters.length; i++) { 
      MethodParameter parameter = parameters[i]; 
      parameter.initParameterNameDiscovery(this.parameterNameDiscoverer); 
      GenericTypeResolver.resolveParameterType(parameter, getBean().getClass());//获取参数的类型（处理参数中的泛型） 
      args[i] = resolveProvidedArgument(parameter, providedArgs);//如果提供了参数的值的话，直接返回 
      if (args[i] != null) { 
        continue; 
      } 
      if (this.argumentResolvers.supportsParameter(parameter)) { //(1) 支持的参数类型 
        try { 
          args[i] = this.argumentResolvers.resolveArgument( // (2) 给参数赋值、校验的一些操作 
              parameter, mavContainer, request, this.dataBinderFactory); 
          continue; 
        } 
        catch (Exception ex) { 
          if (logger.isDebugEnabled()) { 
            logger.debug(getArgumentResolutionErrorMessage("Error resolving argument", i), ex); 
          } 
          throw ex; 
        } 
      } 
      if (args[i] == null) { 
        String msg = getArgumentResolutionErrorMessage("No suitable resolver for argument", i); 
        throw new IllegalStateException(msg); 
      } 
    } 
    return args; 
  } 

private HandlerMethodArgumentResolver getArgumentResolver(MethodParameter parameter) { 
  HandlerMethodArgumentResolver result = this.argumentResolverCache.get(parameter);//如果缓存中已经存在了，则从缓存中取 
  if (result == null) { 
    for (HandlerMethodArgumentResolver methodArgumentResolver : this.argumentResolvers) {//遍历所有的参数解析器 
      if (logger.isTraceEnabled()) { 
        logger.trace("Testing if argument resolver [" + methodArgumentResolver + "] supports [" + 
            parameter.getGenericParameterType() + "]"); 
      } 
      if (methodArgumentResolver.supportsParameter(parameter)) {//匹配合适的参数解析器并放入到缓存中 
        result = methodArgumentResolver; 
        this.argumentResolverCache.put(parameter, result); 
        break; 
      } 
    } 
  } 
  return result; 
} 

  public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, 
      NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception { 
//这里是对参数的解析赋值 
    Object arg = readWithMessageConverters(webRequest, parameter, parameter.getGenericParameterType());//[1] 
    String name = Conventions.getVariableNameForParameter(parameter); 
//获取参数校验的具体类 
    WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name); 
    if (arg != null) { 
      validateIfApplicable(binder, parameter);//进行参数校验 
      if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) { 
        throw new MethodArgumentNotValidException(parameter, binder.getBindingResult()); 
      } 
    } 
    mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult()); 
 
    return arg; 
  } 

  @Override 
  protected <T> Object readWithMessageConverters(NativeWebRequest webRequest, MethodParameter methodParam, 
      Type paramType) throws IOException, HttpMediaTypeNotSupportedException, HttpMessageNotReadableException { 
//获取请求对象 
    HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class); 
    ServletServerHttpRequest inputMessage = new ServletServerHttpRequest(servletRequest); 
//从请求输入流中解析出参数的值 
    Object arg = readWithMessageConverters(inputMessage, methodParam, paramType); 
    if (arg == null) { 
      if (checkRequired(methodParam)) {//校验参数是不是必须的 
        throw new HttpMessageNotReadableException("Required request body is missing: " + 
            methodParam.getMethod().toGenericString()); 
      } 
    } 
    return arg; 
  } 

inputMessage = getAdvice().beforeBodyRead(inputMessage, param, targetType, converterType); 
body = genericConverter.read(targetType, contextClass, inputMessage);[1] 
body = getAdvice().afterBodyRead(body, inputMessage, param, targetType, converterType); 

@Override 
public Object read(Type type, Class<?> contextClass, HttpInputMessage inputMessage) 
    throws IOException, HttpMessageNotReadableException { 
/获取Java中的类型 
  JavaType javaType = getJavaType(type, contextClass); 
  return readJavaType(javaType, inputMessage);//按照Java的类型，为参数赋值 
} 

private Object readJavaType(JavaType javaType, HttpInputMessage inputMessage) { 
  try { 
    if (inputMessage instanceof MappingJacksonInputMessage) { 
      Class<?> deserializationView = ((MappingJacksonInputMessage) inputMessage).getDeserializationView(); 
      if (deserializationView != null) { 
        return this.objectMapper.readerWithView(deserializationView).forType(javaType). 
            readValue(inputMessage.getBody()); 
      } 
    } 
    return this.objectMapper.readValue(inputMessage.getBody(), javaType);//[1]调用Jackson中的方法，解析Body的内容，赋值为java的类型 
  } 
  catch (IOException ex) { 
    throw new HttpMessageNotReadableException("Could not read document: " + ex.getMessage(), ex); 
  } 
} 

@RequestMapping(value ="testJson") 
public String testJson(HttpServletRequest request){ 
  try { 
    InputStream inputStream = request.getInputStream(); 
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); 
    byte[] bytes = new byte[1024]; 
    int flag = 0; 
    while ((flag = inputStream.read(bytes)) > 0){ 
      byteArrayOutputStream.write(bytes,0,flag); 
    } 
    System.out.println(new String(byteArrayOutputStream.toByteArray(),request.getCharacterEncoding())); 
  } catch (IOException e) { 
    e.printStackTrace(); 
  } 
  return "jsonp"; 
}