{"id":819,"date":"2012-03-11T21:09:25","date_gmt":"2012-03-11T20:09:25","guid":{"rendered":"http:\/\/doanduyhai.wordpress.com\/?p=819"},"modified":"2012-03-11T21:09:25","modified_gmt":"2012-03-11T20:09:25","slug":"spring-mvc-part-ii-requestmapping-internals","status":"publish","type":"post","link":"https:\/\/www.doanduyhai.com\/blog\/?p=819","title":{"rendered":"Spring MVC part II : @RequestMapping internals"},"content":{"rendered":"

This post follows upon the Spring MVC part I : Request Handling<\/a> topic.<\/p>\n

In this post we discuss in details how Spring handles the @RequestMapping<\/strong> annotation set on handler methods.<\/p>\n

<\/p>\n

I @RequestMapping arguments resolver<\/h1>\n

The argument resolver is done in the invokeHandlerMethod()<\/em> method of the class org.springframework.web.bind.annotation.support.HandlerMethodInvoker<\/strong>.<\/p>\n

A @SessionAttributes<\/em> & @ModelAttribute<\/em> handling<\/h3>\n
\npublic final Object invokeHandlerMethod(Method handlerMethod, Object handler,\nNativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {\n\n\tMethod handlerMethodToInvoke = BridgeMethodResolver.findBridgedMethod(handlerMethod);\n\ttry {\n\t\tboolean debug = logger.isDebugEnabled();\n\t\tfor (String attrName : this.methodResolver.getActualSessionAttributeNames()) {\n\t\t\tObject attrValue = this.sessionAttributeStore.retrieveAttribute(webRequest, attrName);\n\t\t\tif (attrValue != null) {\n\t\t\t\timplicitModel.addAttribute(attrName, attrValue);\n\t\t\t}\n\t\t}\n\t\tfor (Method attributeMethod : this.methodResolver.getModelAttributeMethods()) {\n\t\t\tMethod attributeMethodToInvoke = BridgeMethodResolver.findBridgedMethod(attributeMethod);\n\t\t\tObject[] args = resolveHandlerArguments(attributeMethodToInvoke, handler, webRequest, implicitModel);\n\t\t\t...\t\n\t\t\tString attrName = AnnotationUtils.findAnnotation(attributeMethod, ModelAttribute.class).value();\n\t\t\tif (!&quot;&quot;.equals(attrName) &amp;&amp; implicitModel.containsAttribute(attrName)) {\n\t\t\t\tcontinue;\n\t\t\t}\n\t\t\tReflectionUtils.makeAccessible(attributeMethodToInvoke);\n\t\t\tObject attrValue = attributeMethodToInvoke.invoke(handler, args);\n\t\t\tif (&quot;&quot;.equals(attrName)) {\n\t\t\t\tClass resolvedType = GenericTypeResolver.resolveReturnType(attributeMethodToInvoke, handler.getClass());\n\t\t\t\tattrName = Conventions.getVariableNameForReturnType(attributeMethodToInvoke, resolvedType, attrValue);\n\t\t\t}\n\t\t\tif (!implicitModel.containsAttribute(attrName)) {\n\t\t\t\timplicitModel.addAttribute(attrName, attrValue);\n\t\t\t}\n\t\t}\n\t\tObject[] args = resolveHandlerArguments(handlerMethodToInvoke, handler, webRequest, implicitModel);\n\t\t...\t\n\t\tReflectionUtils.makeAccessible(handlerMethodToInvoke);\n\t\treturn handlerMethodToInvoke.invoke(handler, args);\n\t}\n\t...\n}\n<\/pre>\n
 The first for<\/strong> loop at line 7<\/strong> simply injects into the implicit model HashMap all attributes declared in the @SessionAttributes<\/strong> annotation. These attributes are retrieved from the HTTP session.<\/p>\n
 The second for<\/strong> loop at line 11<\/strong> executes all methods in the current request handler that are annotated with @ModelAttribute<\/strong><\/p>\n
\n...\n@ModelAttribute(&quot;page&quot;)\npublic String getPage()\n{\n\treturn &quot;adminPage&quot;;\n}\n...\n@ModelAttribute(&quot;user&quot;)\npublic String getUser()\n{\n\treturn this.userService.getCurrentLoggedUser();\n}\n...\n<\/pre>\n
 These methods are supposed to be called for each request<\/strong> and the returned object is added to the implicit model HashMap (line 28<\/strong>).<\/p>\n
 Finally, the method arguments are resolved by calling resolveHandlerArguments()<\/em> at line 31<\/strong>
\n <\/p>\n
B Argument types resolution<\/h3>\n
\nprivate Object[] resolveHandlerArguments(Method handlerMethod, Object handler,\nNativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {\n\n\tClass[] paramTypes = handlerMethod.getParameterTypes();\n\tObject[] args = new Object[paramTypes.length];\n\n\tfor (int i = 0; i &lt; args.length; i++) {\n\t\tMethodParameter methodParam = new MethodParameter(handlerMethod, i);\n\t\tmethodParam.initParameterNameDiscovery(this.parameterNameDiscoverer);\n\t\tGenericTypeResolver.resolveParameterType(methodParam, handler.getClass());\n\t\tString paramName = null;\n\t\tString headerName = null;\n\t\tboolean requestBodyFound = false;\n\t\tString cookieName = null;\n\t\tString pathVarName = null;\n\t\tString attrName = null;\n\t\tboolean required = false;\n\t\tString defaultValue = null;\n\t\tboolean validate = false;\n\t\tObject[] validationHints = null;\n\t\tint annotationsFound = 0;\n\t\tAnnotation[] paramAnns = methodParam.getParameterAnnotations();\n\t\tfor (Annotation paramAnn : paramAnns) {\n\t\t\tif (RequestParam.class.isInstance(paramAnn)) {\n\t\t\t\tRequestParam requestParam = (RequestParam) paramAnn;\n\t\t\t\tparamName = requestParam.value();\n\t\t\t\trequired = requestParam.required();\n\t\t\t\tdefaultValue = parseDefaultValueAttribute(requestParam.defaultValue());\n\t\t\t\tannotationsFound++;\n\t\t\t}\n\t\t\telse if (RequestHeader.class.isInstance(paramAnn)) {\n\t\t\t\tRequestHeader requestHeader = (RequestHeader) paramAnn;\n\t\t\t\theaderName = requestHeader.value();\n\t\t\t\trequired = requestHeader.required();\n\t\t\t\tdefaultValue = parseDefaultValueAttribute(requestHeader.defaultValue());\n\t\t\t\tannotationsFound++;\n\t\t\t}\n\t\t\telse if (RequestBody.class.isInstance(paramAnn)) {\n\t\t\t\trequestBodyFound = true;\n\t\t\t\tannotationsFound++;\n\t\t\t}\n\t\t\telse if (CookieValue.class.isInstance(paramAnn)) {\n\t\t\t\tCookieValue cookieValue = (CookieValue) paramAnn;\n\t\t\t\tcookieName = cookieValue.value();\n\t\t\t\trequired = cookieValue.required();\n\t\t\t\tdefaultValue = parseDefaultValueAttribute(cookieValue.defaultValue());\n\t\t\t\tannotationsFound++;\n\t\t\t}\n\t\t\telse if (PathVariable.class.isInstance(paramAnn)) {\n\t\t\t\tPathVariable pathVar = (PathVariable) paramAnn;\n\t\t\t\tpathVarName = pathVar.value();\n\t\t\t\tannotationsFound++;\n\t\t\t}\n\t\t\telse if (ModelAttribute.class.isInstance(paramAnn)) {\n\t\t\t\tModelAttribute attr = (ModelAttribute) paramAnn;\n\t\t\t\tattrName = attr.value();\n\t\t\t\tannotationsFound++;\n\t\t\t}\n\t\t\telse if (Value.class.isInstance(paramAnn)) {\n\t\t\t\tdefaultValue = ((Value) paramAnn).value();\n\t\t\t}\n\t\t\telse if (paramAnn.annotationType().getSimpleName().startsWith(&quot;Valid&quot;)) {\n\t\t\t\tvalidate = true;\n\t\t\t\tObject value = AnnotationUtils.getValue(paramAnn);\n\t\t\t\tvalidationHints = (value instanceof Object[] ? (Object[]) value : new Object[] {value});\n\t\t\t}\n\t\t}\n\n\t\tif (annotationsFound &gt; 1) {\n\t\t\tthrow new IllegalStateException(&quot;Handler parameter annotations are exclusive choices - &quot; +&quot;do not specify more than one such annotation on the same parameter: &quot; + handlerMethod);\n\t\t}\n\t\tif (annotationsFound == 0) {\n\t\t\tObject argValue = resolveCommonArgument(methodParam, webRequest);\n\t\t\tif (argValue != WebArgumentResolver.UNRESOLVED) {\n\t\t\t\targs[i] = argValue;\n\t\t\t}\n\t\t\telse if (defaultValue != null) {\n\t\t\t\targs[i] = resolveDefaultValue(defaultValue);\n\t\t\t}\n\t\t\telse {\n\t\t\t\tClass&lt;?&gt; paramType = methodParam.getParameterType();\n\t\t\t\tif (Model.class.isAssignableFrom(paramType) || Map.class.isAssignableFrom(paramType)) {\n\t\t\t\t\tif (!paramType.isAssignableFrom(implicitModel.getClass())) {\n\t\t\t\t\t\tthrow new IllegalStateException(&quot;Argument [&quot; + paramType.getSimpleName() + &quot;] is of type &quot; +\t\t\t\t\t\t\t\t&quot;Model or Map but is not assignable from the actual model. You may need to switch &quot; +\t\t\t&quot;newer MVC infrastructure classes to use this argument.&quot;);\n\t\t\t\t\t}\n\t\t\t\t\targs[i] = implicitModel;\n\t\t\t\t}\n\t\t\t\telse if (SessionStatus.class.isAssignableFrom(paramType)) {\n\t\t\t\t\targs[i] = this.sessionStatus;\n\t\t\t\t}\n\t\t\t\telse if (HttpEntity.class.isAssignableFrom(paramType)) {\n\t\t\t\t\targs[i] = resolveHttpEntityRequest(methodParam, webRequest);\n\t\t\t\t}\n\t\t\t\telse if (Errors.class.isAssignableFrom(paramType)) {\n\t\t\t\t\tthrow new IllegalStateException(&quot;Errors\/BindingResult argument declared &quot; +&quot;without preceding model attribute. Check your handler method signature!&quot;);\n\t\t\t\t}\n\t\t\t\telse if (BeanUtils.isSimpleProperty(paramType)) {\n\t\t\t\t\tparamName = &quot;&quot;;\n\t\t\t\t}\n\t\t\t\telse {\n\t\t\t\t\tattrName = &quot;&quot;;\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t\tif (paramName != null) {\n\t\t\targs[i] = resolveRequestParam(paramName, required, defaultValue, methodParam, webRequest, handler);\n\t\t}\n\t\telse if (headerName != null) {\n\t\t\targs[i] = resolveRequestHeader(headerName, required, defaultValue, methodParam, webRequest, handler);\n\t\t}\n\t\telse if (requestBodyFound) {\n\t\t\targs[i] = resolveRequestBody(methodParam, webRequest, handler);\n\t\t}\n\t\telse if (cookieName != null) {\n\t\t\targs[i] = resolveCookieValue(cookieName, required, defaultValue, methodParam, webRequest, handler);\n\t\t}\n\t\telse if (pathVarName != null) {\n\t\t\targs[i] = resolvePathVariable(pathVarName, methodParam, webRequest, handler);\n\t\t}\n\t\telse if (attrName != null) {\n\t\t\tWebDataBinder binder =\n\t\t\t\t\tresolveModelAttribute(attrName, methodParam, implicitModel, webRequest, handler);\n\t\t\tboolean assignBindingResult = (args.length &gt; i + 1 &amp;&amp; Errors.class.isAssignableFrom(paramTypes[i + 1]));\n\t\t\tif (binder.getTarget() != null) {\n\t\t\t\tdoBind(binder, webRequest, validate, validationHints, !assignBindingResult);\n\t\t\t}\n\t\t\targs[i] = binder.getTarget();\n\t\t\tif (assignBindingResult) {\n\t\t\t\targs[i + 1] = binder.getBindingResult();\n\t\t\t\ti++;\n\t\t\t}\n\t\t\timplicitModel.putAll(binder.getBindingResult().getModel());\n\t\t}\n\t}\n\t\treturn args;\n}\n<\/pre>\n
 The for<\/strong> loop at line 23<\/strong> lists all argument types having supported annotations:<\/p>\n
    \n
  • line 24<\/strong>: @RequestPara<\/strong>m annotated argument<\/li>\n
  • line 31<\/strong>: @RequestHeader<\/strong> annotated argument<\/li>\n
  • line 38<\/strong>: @RequestBody<\/strong> annotated argument<\/li>\n
  • line 42<\/strong>: @CookieValue<\/strong> annotated argument<\/li>\n
  • line 49<\/strong>: @PathVariable<\/strong> annotated argument<\/li>\n
  • line 54<\/strong>: @ModelAttribute<\/strong> annotated argument<\/li>\n
  • line 62<\/strong>: @Valid<\/strong> annotated argument<\/li>\n<\/ul>\n
     If an argument is annotated more than once, Spring will raise an exception as per line 70<\/strong><\/p>\n
    Next, the method resolveCommonArgument()<\/em> is called if the argument has no annotation (line 73<\/strong>).<\/p>\n
    If the argument is of type<\/p>\n
      \n
    • Model<\/strong> or Map<\/strong> (java.util.Map), the implicit model HashMap built earlier will be returned (line 86<\/strong>)<\/li>\n
    • SessionStatus<\/strong>, the current session status object is returned (line 89<\/strong>)<\/li>\n
    • HttpEntity<\/strong>, the method resolveHttpEntityRequest() is called for resolution (line 92<\/strong>)<\/li>\n<\/ul>\n
      At lines 106, 109, 112, 115, 118 & 122<\/strong>, Spring resolves the arguments based on their annotation. Custom data binders, if any, are invoked at line 125<\/strong>.<\/p>\n
      Let’s focus on the resolveModelAttribute()<\/em> method at line 122<\/strong>. This method resolves all argument annotated by @ModelAttribute<\/strong><\/p>\n
      \nprivate WebDataBinder resolveModelAttribute(String attrName, MethodParameter methodParam,\nExtendedModelMap implicitModel, NativeWebRequest webRequest, Object handler) throws Exception {\n\n\t\/\/ Bind request parameter onto object...\n\tString name = attrName;\n\tif (&quot;&quot;.equals(name)) {\n\t\tname = Conventions.getVariableNameForParameter(methodParam);\n\t}\n\tClass&lt;?&gt; paramType = methodParam.getParameterType();\n\tObject bindObject;\n\tif (implicitModel.containsKey(name)) {\n\t\tbindObject = implicitModel.get(name);\n\t}\n\telse if (this.methodResolver.isSessionAttribute(name, paramType)) {\n\t\tbindObject = this.sessionAttributeStore.retrieveAttribute(webRequest, name);\n\t\tif (bindObject == null) {\n\t\t\traiseSessionRequiredException(&quot;Session attribute '&quot; + name + &quot;' required - not bound in session&quot;);\n\t\t}\n\t}\n\telse {\n\t\tbindObject = BeanUtils.instantiateClass(paramType);\n\t}\n\tWebDataBinder binder = createBinder(webRequest, bindObject, name);\n\tinitBinder(handler, name, binder, webRequest);\n\treturn binder;\n}\n<\/pre>\n
       As expected, if the arugment name is found in the implicit model HashMap, the value is returned (line 12<\/strong>) otherwise the value is search in the HTTP session itself (line 15<\/strong>).<\/p>\n
       Please notice at lines 23 & 24<\/strong> the initialization of a WebDataBinder<\/strong> to bind request parameter to a particular type.<\/p>\n
       Now let’s see how Spring resolves common arguments:<\/p>\n
      \nprotected Object resolveCommonArgument(MethodParameter methodParameter, NativeWebRequest webRequest)\nthrows Exception {\n\n\t\/\/ Invoke custom argument resolvers if present...\n\tif (this.customArgumentResolvers != null) {\n\t\tfor (WebArgumentResolver argumentResolver : this.customArgumentResolvers) {\n\t\t\tObject value = argumentResolver.resolveArgument(methodParameter, webRequest);\n\t\t\tif (value != WebArgumentResolver.UNRESOLVED) {\n\t\t\t\treturn value;\n\t\t\t}\n\t\t}\n\t}\n\t\/\/ Resolution of standard parameter types...\n\tClass paramType = methodParameter.getParameterType();\n\tObject value = resolveStandardArgument(paramType, webRequest);\n\tif (value != WebArgumentResolver.UNRESOLVED &amp;&amp; !ClassUtils.isAssignableValue(paramType, value)) {\n\t\tthrow new IllegalStateException(&quot;Standard argument type [&quot; + paramType.getName() +\n\t\t\t\t&quot;] resolved to incompatible value of type [&quot; + (value != null ? value.getClass() : null) +\n\t\t\t\t&quot;]. Consider declaring the argument type in a less specific fashion.&quot;);\n\t}\n\treturn value;\n}\n<\/pre>\n
       If you have declared custom argument resolvers, they are invoked here (line 5<\/strong>) otherwise Spring tries to resolve the argument by calling resolveStandardArgument()<\/em> (line 15<\/strong>) which matches only all argument of type WebRequest<\/strong> or NativeWebRequest<\/strong>.<\/p>\n
       <\/p>\n
      II Model and View resolution<\/h1>\n
      Remember the invokedHandlerMethod()<\/em> discussed in the previous topic ? <\/p>\n
      \nprotected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, Object handler)\tthrows Exception {\n\n\tServletHandlerMethodResolver methodResolver = getMethodResolver(handler);\n\tMethod handlerMethod = methodResolver.resolveHandlerMethod(request);\n\tServletHandlerMethodInvoker methodInvoker = new ServletHandlerMethodInvoker(methodResolver);\n\tServletWebRequest webRequest = new ServletWebRequest(request, response);\n\tExtendedModelMap implicitModel = new BindingAwareModelMap();\n\n\tObject result = methodInvoker.invokeHandlerMethod(handlerMethod, handler, webRequest, implicitModel);\n\tModelAndView mav =\nmethodInvoker.getModelAndView(handlerMethod, handler.getClass(), result, implicitModel, webRequest);\n\tmethodInvoker.updateModelAttributes(handler, (mav != null ? mav.getModel() : null), implicitModel, webRequest);\n\treturn mav;\n}\n <\/pre>\n
       In this chapter we zoom in the getModelAndView()<\/em> internals<\/p>\n
      \npublic ModelAndView getModelAndView(Method handlerMethod, Class handlerType, Object returnValue,\nExtendedModelMap implicitModel, ServletWebRequest webRequest) throws Exception {\n\n\tResponseStatus responseStatusAnn = AnnotationUtils.findAnnotation(handlerMethod, ResponseStatus.class);\n\tif (responseStatusAnn != null) {\n\t\t\tHttpStatus responseStatus = responseStatusAnn.value();\n\t\t\tString reason = responseStatusAnn.reason();\n\t\t\tif (!StringUtils.hasText(reason)) {\n\t\t\t\twebRequest.getResponse().setStatus(responseStatus.value());\n\t\t\t}\n\t\t\telse {\n\t\t\t\twebRequest.getResponse().sendError(responseStatus.value(), reason);\n\t\t\t}\n\t\t\t\/\/ to be picked up by the RedirectView\n\t\t\twebRequest.getRequest().setAttribute(View.RESPONSE_STATUS_ATTRIBUTE, responseStatus);\n\n\t\t\tresponseArgumentUsed = true;\n\t\t}\n\n\t\t\/\/ Invoke custom resolvers if present...\n\t\tif (customModelAndViewResolvers != null) {\n\t\t\tfor (ModelAndViewResolver mavResolver : customModelAndViewResolvers) {\n\t\t\t\tModelAndView mav = mavResolver.resolveModelAndView(\n\t\t\t\t\t\thandlerMethod, handlerType, returnValue, implicitModel, webRequest);\n\t\t\t\tif (mav != ModelAndViewResolver.UNRESOLVED) {\n\t\t\t\t\treturn mav;\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\n\t\tif (returnValue instanceof HttpEntity) {\n\t\t\thandleHttpEntityResponse((HttpEntity&lt;?&gt;) returnValue, webRequest);\n\t\t\treturn null;\n\t\t}\n\t\telse if (AnnotationUtils.findAnnotation(handlerMethod, ResponseBody.class) != null) {\n\t\t\thandleResponseBody(returnValue, webRequest);\n\t\t\treturn null;\n\t\t}\n\t\telse if (returnValue instanceof ModelAndView) {\n\t\t\tModelAndView mav = (ModelAndView) returnValue;\n\t\t\tmav.getModelMap().mergeAttributes(implicitModel);\n\t\t\treturn mav;\n\t\t}\n\t\telse if (returnValue instanceof Model) {\n\t\t\treturn new ModelAndView().addAllObjects(implicitModel).addAllObjects(((Model) returnValue).asMap());\n\t\t}\n\t\telse if (returnValue instanceof View) {\n\t\t\treturn new ModelAndView((View) returnValue).addAllObjects(implicitModel);\n\t\t}\n\t\telse if (AnnotationUtils.findAnnotation(handlerMethod, ModelAttribute.class) != null) {\n\t\t\taddReturnValueAsModelAttribute(handlerMethod, handlerType, returnValue, implicitModel);\n\t\t\treturn new ModelAndView().addAllObjects(implicitModel);\n\t\t}\n\t\telse if (returnValue instanceof Map) {\n\t\t\treturn new ModelAndView().addAllObjects(implicitModel).addAllObjects((Map) returnValue);\n\t\t}\n\t\telse if (returnValue instanceof String) {\n\t\t\treturn new ModelAndView((String) returnValue).addAllObjects(implicitModel);\n\t\t}\n\t\telse if (returnValue == null) {\n\t\t\t\/\/ Either returned null or was 'void' return.\n\t\t\tif (this.responseArgumentUsed || webRequest.isNotModified()) {\n\t\t\t\treturn null;\n\t\t\t}\n\t\t\telse {\n\t\t\t\t\/\/ Assuming view name translation...\n\t\t\t\treturn new ModelAndView().addAllObjects(implicitModel);\n\t\t\t}\n\t\t}\n\t\telse if (!BeanUtils.isSimpleProperty(returnValue.getClass())) {\n\t\t\t\/\/ Assume a single model attribute...\n\t\t\taddReturnValueAsModelAttribute(handlerMethod, handlerType, returnValue, implicitModel);\n\t\t\treturn new ModelAndView().addAllObjects(implicitModel);\n\t\t}\n\t\telse {\n\t\t\tthrow new IllegalArgumentException(&quot;Invalid handler method return value: &quot; + returnValue);\n\t\t}\n\t}\n<\/pre>\n
       The if<\/strong> block at line 5<\/strong> injects a ResponseStatus<\/strong> object into the request response.
      \n Then, if custom view and model resolvers<\/strong> have been declared, they are invoked (line 21<\/strong>)
      \n The case of HttpEntity<\/strong> and @ResponseBody<\/strong> returned value type are processed at lines 32 & 36<\/strong><\/p>\n
      From line 39<\/strong> to line 69<\/strong>, all returned types from Model<\/strong>, View<\/strong>, ModelAndView<\/strong>, String<\/strong>, Map<\/strong> or @ModelAttribute<\/strong> are handled. In most cases a ModelAndView<\/strong> object is created and the implicit model HashMap is added to this object as well as the view name, if present.<\/p>\n
       If the returned value is of primitive or any type not listed above, a simple ModelAndView object is created, fileld with the implicit model and returned (line 72<\/strong>).
      \n <\/p>\n
      III Model attributes update<\/h1>\n
      Last but not least, let’s see how Spring updates the model attributes before calling view renderers<\/p>\n
      \npublic final void updateModelAttributes(Object handler, Map&lt;String, Object&gt; mavModel,\nExtendedModelMap implicitModel, NativeWebRequest webRequest) throws Exception {\n\n\tif (this.methodResolver.hasSessionAttributes() &amp;&amp; this.sessionStatus.isComplete()) {\n\t\tfor (String attrName : this.methodResolver.getActualSessionAttributeNames()) {\n\t\t\tthis.sessionAttributeStore.cleanupAttribute(webRequest, attrName);\n\t\t}\n\t}\n\t\/\/ Expose model attributes as session attributes, if required.\n\t\/\/ Expose BindingResults for all attributes, making custom editors available.\n\tMap&lt;String, Object&gt; model = (mavModel != null ? mavModel : implicitModel);\n\tif (model != null) {\n\t\ttry {\n\t\t\tString[] originalAttrNames = model.keySet().toArray(new String[model.size()]);\n\t\t\tfor (String attrName : originalAttrNames) {\n\t\t\t\tObject attrValue = model.get(attrName);\n\t\t\t\tboolean isSessionAttr = this.methodResolver.isSessionAttribute(\n\t\t\t\t\t\tattrName, (attrValue != null ? attrValue.getClass() : null));\n\t\t\t\tif (isSessionAttr) {\n\t\t\t\t\tif (this.sessionStatus.isComplete()) {\n\t\t\t\t\t\timplicitModel.put(MODEL_KEY_PREFIX_STALE + attrName, Boolean.TRUE);\n\t\t\t\t\t}\n\t\t\t\t\telse if (!implicitModel.containsKey(MODEL_KEY_PREFIX_STALE + attrName)) {\n\t\t\t\t\t\tthis.sessionAttributeStore.storeAttribute(webRequest, attrName, attrValue);\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tif (!attrName.startsWith(BindingResult.MODEL_KEY_PREFIX) &amp;&amp;\n\t\t\t\t\t\t(isSessionAttr || isBindingCandidate(attrValue))) {\n\t\t\t\t\tString bindingResultKey = BindingResult.MODEL_KEY_PREFIX + attrName;\n\t\t\t\t\tif (mavModel != null &amp;&amp; !model.containsKey(bindingResultKey)) {\n\t\t\t\t\t\tWebDataBinder binder = createBinder(webRequest, attrValue, attrName);\n\t\t\t\t\t\tinitBinder(handler, attrName, binder, webRequest);\n\t\t\t\t\t\tmavModel.put(bindingResultKey, binder.getBindingResult());\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t\tcatch (InvocationTargetException ex) {\n\t\t\t\/\/ User-defined @InitBinder method threw an exception...\n\t\t\tReflectionUtils.rethrowException(ex.getTargetException());\n\t\t}\n\t}\n}\n<\/pre>\n
       At line 6<\/strong>, we can see that if the session status is set to complete, Spring will remove all attributes declared in @SessionAttributes<\/strong> from the HTTP session.<\/p>\n
       Next, the normal processing flow is invoked. Please notice the line 24<\/strong> where all session attributes are registered into the HTTP session.<\/p>\n
       For each model attribute candidate to a custom data binder, Spring will create one and call the binding method before putting the result into the ModelAndView map (lines 31 to 33<\/strong>).<\/p>\n","protected":false},"excerpt":{"rendered":"
      This post follows upon the Spring MVC part I : Request Handling topic. In this post we discuss in details how Spring handles the @RequestMapping annotation set on handler methods.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[31,19],"tags":[],"_links":{"self":[{"href":"https:\/\/www.doanduyhai.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/819"}],"collection":[{"href":"https:\/\/www.doanduyhai.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.doanduyhai.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.doanduyhai.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.doanduyhai.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=819"}],"version-history":[{"count":0,"href":"https:\/\/www.doanduyhai.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/819\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.doanduyhai.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=819"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.doanduyhai.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=819"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.doanduyhai.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=819"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}