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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.
There are two ways to use interceptor with Spring MVC.
Spring MVC tutorial:
- Spring MVC hello world example
- Spring MVC Hibernate MySQL example
- Spring MVC interceptor example
- Spring MVC angularjs example
- Spring MVC @RequestMapping example
- Spring Component,Service, Repository and Controller example
- Spring MVC @ModelAttribute annotation example
- Spring MVC @RestController annotation example
- Spring MultiActionController Example
- Spring MVC ModelMapSpring MVC file upload example
- Spring restful web service example
- Spring restful web service json example
- Spring Restful web services CRUD example
- Spring security hello world example
- Spring security custom login form example
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) : Â 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](https://java2blog.com/abstract-class-java/ “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.
Adding Spring MVC dependency
Add spring dependency in pom.xml. We require spring core and spring mvc dependency here.
pom.xmlÂ
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.arpit.java2blog</groupId> <artifactId>SpringMVCHelloWorldExample</artifactId> <packaging>war</packaging> <version>0.0.1-SNAPSHOT</version> <name>SpringMVCHelloWorldExample Maven Webapp</name> <url>http://maven.apache.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> </dependency> </dependencies> <build> <finalName>SpringMVCHelloWorldExample</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.1</version> <configuration> <source>${jdk.version}</source> <target>${jdk.version}</target> </configuration> </plugin> </plugins> </build> <properties> <spring.version>4.2.1.RELEASE</spring.version> <jdk.version>1.7</jdk.version> </properties> </project> |
Create ControllerÂ
Create a package named “org.arpit.java2blog.springmvc.controller”
create a controller class named “HelloWorldController.java”
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package org.arpit.java2blog.springmvc.controller; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.servlet.ModelAndView; @Controller public class HelloWorldController { @RequestMapping("/helloworld") public ModelAndView hello() { return new ModelAndView("hello"); } } |
Create interceptorÂ
create interceptor class called SampleInterceptor.java
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package org.arpit.java2blog.springmvc.interceptor; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.servlet.handler.HandlerInterceptorAdapter; public class SampleInterceptor extends HandlerInterceptorAdapter { @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { request.setAttribute("blogName", "java2blog"); return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { String blogName = (String) request.getAttribute("blogName"); // We are adding some modelAndView objects here and will use it in view jsp. modelAndView.addObject("blogName",blogName); modelAndView.addObject("authorName", "Arpit"); } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { String blogName = (String) request.getAttribute("blogName"); String authorName = (String) request.getAttribute("authorName"); System.out.println("Request URL::" + request.getRequestURL().toString()); System.out.println("Blog name : " + blogName); System.out.println("Author Name : " + authorName); } } |
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
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<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>HelloWorld</title> </head> <body> <a href="helloworld.html">Click here to read hello message </a> </body> </html> |
Create hello.jsp in /WEB-INF/ folder
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<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Hello</title> </head> <body> This is written by ${authorName} on ${blogName} </body> </html> |
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.
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<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> <display-name>Archetype Created Web Application</display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>springmvc-dispatcher</servlet-name> <servlet-class> org.springframework.web.servlet.DispatcherServlet </servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>springmvc-dispatcher</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> </web-app> |
create xml file named “springmvc-dispatcher-servlet.xml” in /WEB-INF folder as below.
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<beans:beans xmlns="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <context:component-scan base-package="org.arpit.java2blog.springmvc.controller" /> <beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <beans:property name="prefix" value="/WEB-INF/"/> <beans:property name="suffix" value=".jsp" /> </beans:bean> <interceptors> <interceptor> <mapping path="/helloworld.html" /> <beans:bean class="org.arpit.java2blog.springmvc.interceptor.SampleInterceptor"></beans:bean> </interceptor> </interceptors> </beans:beans> |
create xml file named “springmvc-dispatcher-servlet.xml” in /WEB-INF folder as below.
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> |
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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