Spring MVC interceptor HandleInterceptorAdapter example

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Sometimes you need to intercept incoming request and do some preprocessing or you need to do it after completion of request. It is very much similar to filters that we use with servlet.
There are two ways to use interceptor with Spring MVC.

Spring MVC tutorial:

HandlerInterceptor Interface :

We can implement HandlerInterceptor interface to use interceptor. It has three methods which we need to implement.

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) : This method is executed before request is handed over to handler method.
If you notice it has boolean return type. If this method returns true, then it will go to other interceptors or to handler method. If this method returns false then this request is handled by interceptor only and we should use response object to send back to client.
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) : This method is called when handler method has completed its process but dispatcherServlet is yet process the view. This method can be use to add some model view objects that can be used in view. It can be done by adding object to modelAndView object.
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) :  This method is called after view is render and request is completely processed.

HandlerInterceptorAdapter class:

Issue with HandlerInterceptor is that you need to implement all the methods but if you extend to abstract class called HandlerInterceptorAdapter, you can implement only those method which you want and other methods will have default implementation.

Lets implement custom interceptor example using HandlerInterceptorAdapter class.

Spring MVC interceptor example:

I am using Spring MVC hello world example here with small changes to it.

Spring MVC interceptor project structure

Adding Spring MVC dependency

Add spring dependency in pom.xml. We require spring core and spring mvc dependency here.
pom.xml 

Create Controller 

Create a package named “org.arpit.java2blog.springmvc.controller”
create a controller class named “HelloWorldController.java”

Create interceptor 

create interceptor class called SampleInterceptor.java

Here I am setting request attribute(blogName) in preHandle method and we are getting it in postHandle method. We are also adding two objects to modelAndView which we will use in jsp.

Create view

Modify index.jsp as below

Create hello.jsp in /WEB-INF/ folder

Configuring spring mvc application

 Now we need to configure two files “web.xml” and “springmvc-dispatcher-servlet.xml” We need to declare DispatcherServlet in web.xml for spring MVC. When DisplatcherServlet is initialized,spring tries to load application context from [servlet name]-servet.xml file. So in this case, it will be try to load springmvc-dispatcher-servlet.xml.

create xml file named “springmvc-dispatcher-servlet.xml” in /WEB-INF folder as below.

create xml file named “springmvc-dispatcher-servlet.xml” in /WEB-INF folder as below.

Here we have declared interceptor(SampleInterceptor) in above file which will intercept specific URL (/helloworld.html).

It ‘s time to do maven build.

Right click on project -> Run as -> Maven build
Provide goals as clean install (given below) and click on run

Run the application

Right click on project -> run as -> run on server
Select apache tomcat and click on finish

 You will see below screen:



When you click on above link, you will get below screen

We are done with Spring MVC interceptor example. If you are still facing any issue, please comment.

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