SPRINGMVC Learning-Interceptors

• Brief introduction

Spring Web MVC's processor interceptors are similar to the filter filters in servlet development for preprocessing and post-processing of processors.

• Interceptor definition

　　Define the interceptor to implement the Handlerinterceptor interface. Three methods are available in an interface.

1  Public classHandlerInterceptor1ImplementsHandlerinterceptor {2 3     4     //execute before entering the handler method5     //for identity authentication, identity authorization6     //such as identity authentication, if the authentication by means that the current user does not log in, need this method to intercept no longer execution down7 @Override8      Public BooleanPrehandle (httpservletrequest request,9HttpServletResponse response, Object handler)throwsException {Ten          One         //return False indicates interception, not down execution A         //return TRUE indicates release -         return false; -     } the  -     //after entering the handler method, return to Modelandview before executing -     //The scenario starts with Modelandview: Upload common model data (such as menu navigation) to the view here, or you can unify the specified view here - @Override +      Public voidPosthandle (httpservletrequest request, - httpservletresponse Response, Object handler, +Modelandview Modelandview)throwsException { A          at          -     } -  -     //execute handler complete execution of this method -     //Application Scenario: Unified exception handling, unified log processing - @Override in      Public voidaftercompletion (httpservletrequest request, - httpservletresponse Response, Object handler, Exception ex) to             throwsException { +          -          the     } *  $}

• Interceptor Configuration

1, for handlermapping configuration

SPRINGMVC interceptors are set for handlermapping , and if blocking is configured in a handlermapping , the handlermapping the mapping succeeds Handler The Interceptor is eventually used.

1<Bean2     class= "Org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping" >3<property name= "Interceptors" >4<list>5<ref bean= "HandlerInterceptor1"/>6<ref bean= "HandlerInterceptor2"/>7</list>8</property>9</bean>Ten<bean id= "HandlerInterceptor1"class= "Springmvc.intercapter.HandlerInterceptor1"/> One<bean id= "HandlerInterceptor2"class= "Springmvc.intercapter.HandlerInterceptor2"/>

2, the global interceptor

1 <!--Interception Device -2 <mvc:interceptors>3     <!--multiple interceptors, sequential execution -4     <Mvc:interceptor>5         <mvc:mappingPath="/**"/>6         <Beanclass= "Com.luchao.springmvc.filter.HandlerInterceptor1"></Bean>7     </Mvc:interceptor>8     <Mvc:interceptor>9         <mvc:mappingPath="/**"/>Ten         <Beanclass= "Com,luchao.springmvc.filter.handlerinterceptor2"></Bean> One     </Mvc:interceptor> A </mvc:interceptors>

• Intercept test

Write two interceptors to intercept the test.

1, Two interceptors are released .

1 Handlerinterceptor1...prehandle 2 Handlerinterceptor2...prehandle 3 4 Handlerinterceptor2...posthandle 5 Handlerinterceptor1...posthandle 6 7 handlerinterceptor2...aftercompletion 8 Handlerinterceptor1...aftercompletion

Summarize:

The Prehandle method executes sequentially,

Posthandle and aftercompletion are executed in reverse order of interceptor configuration.

2, Interceptor 1 release, Interceptor 2 not released

1 Handlerinterceptor1...prehandle 2 Handlerinterceptor2...prehandle 3 handlerinterceptor1...aftercompletion

Summarize:

Interceptor 1 release, Interceptor 2 prehandle will be executed.

Interceptors 2 Prehandle not released, interceptors 2 posthandle and aftercompletion will not be executed.

Posthandle will not execute as long as an interceptor is not released.

3, Interceptor 1 does not release, Interceptor 2 does not release

1 Handlerinterceptor1...prehandle

Interceptors 1 prehandle not released, Posthandle and Aftercompletion will not be executed.

Interceptor 1 prehandle not release, Interceptor 2 does not execute.

Summarize:

Based on the test results, the interceptor is applied. For example: Unified log processing Interceptor, need the Interceptor Prehandle must be released, and put it in the Interceptor link in the first position. For example: Login to the authentication interceptor, placed in the Interceptor link in the first position. The permission check blocker is placed after the login authentication interceptor. (check permissions only after login)

• Interceptor Application (for login authentication)

1. Controller method

@Controller Public classLogincontroller {//Login@RequestMapping ("/login")     PublicString Login (HttpSession session, string Username, string password)throwsException {//invoking service for user authentication// ...        //Save user identity information in sessionSession.setattribute ("username", username); //REDIRECT to Product List page        return"Redirect:/items/queryitems.action"; }    //Exit@RequestMapping ("/logout")     PublicString Logout (HttpSession session)throwsException {//Clear Sessionsession.invalidate (); //REDIRECT to Product List page        return"Redirect:/items/queryitems.action"; }}

2, Login Authentication Interceptor

1  Public classLogininterceptorImplementsHandlerinterceptor {2 3     4     //execute before entering the handler method5     //for identity authentication, identity authorization6     //such as identity authentication, if the authentication by means that the current user does not log in, need this method to intercept no longer execution down7 @Override8      Public BooleanPrehandle (httpservletrequest request,9HttpServletResponse response, Object handler)throwsException {Ten          One         //gets the requested URL AString URL =Request.getrequesturi (); -         //determine if the URL is a public address (it will be exposed in the address configuration profile when it is actually used) -         //Here the address is the address of the landing submission the         if(Url.indexof ("Login.action") >=0){ -             //If the login is submitted, the release -             return true; -         } +          -         //Judging Session +HttpSession session =request.getsession (); A         //Remove user identity information from the session atString username = (string) session.getattribute ("username"); -          -         if(Username! =NULL){ -             //identity exists, release -             return true; -         } in          -         //Execute here indicates user identity needs authentication, jump landing page toRequest.getrequestdispatcher ("/web-inf/jsp/login.jsp"). Forward (request, response); +          -         //return False indicates interception, not down execution the         //return TRUE indicates release *         return false; $}

SPRINGMVC Learning-Interceptors