Programming for beginners: Spring mvc: SimpleUrlHandlerMapping annotation based configuration

In my previous post, I explained an example of SimpleUrlHandlerMapping using xml based approach. In this post, I am going to rewrite the same example using annotation based approach.

<bean

class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">

<value>

/hello=helloMsg

/welcome=helloMsg

/*/welcome=helloMsg

</value>

</property>

</bean>

Above configurations can be written like below.

@Bean

public SimpleUrlHandlerMapping simpleUrlHandlerMapping() {

SimpleUrlHandlerMapping simpleUrlHandlerMapping = new SimpleUrlHandlerMapping();

Map<String, Object> urlMap = new HashMap<>();

urlMap.put("/hello", helloMsg());

urlMap.put("/welcome", helloMsg());

urlMap.put("/*/welcome", helloMsg());

simpleUrlHandlerMapping.setUrlMap(urlMap);

return simpleUrlHandlerMapping;

}

@Bean

public HelloWorldController helloMsg() {

return new HelloWorldController();

}

Find the below working application.

ApplicationConfig.java

package com.sample.myApp.configs;

import java.util.HashMap;
import java.util.Map;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.handler.SimpleUrlHandlerMapping;

import com.sample.myApp.controllers.HelloWorldController;

@Configuration
public class ApplicationConfig {
 @Bean
 public SimpleUrlHandlerMapping simpleUrlHandlerMapping() {
  SimpleUrlHandlerMapping simpleUrlHandlerMapping = new SimpleUrlHandlerMapping();

  Map<String, Object> urlMap = new HashMap<>();
  urlMap.put("/hello", helloMsg());
  urlMap.put("/welcome", helloMsg());
  urlMap.put("/*/welcome", helloMsg());
  simpleUrlHandlerMapping.setUrlMap(urlMap);

  return simpleUrlHandlerMapping;
 }

 @Bean
 public HelloWorldController helloMsg() {
  return new HelloWorldController();
 }

}

HelloWorldController.java

package com.sample.myApp.controllers;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;

public class HelloWorldController extends AbstractController {

 @Override
 protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)
   throws Exception {
  ModelAndView modelAndView = new ModelAndView("hello");

  modelAndView.addObject("message", "Welcome to Spring MVC framework");
  return modelAndView;

 }

}

Create hello.jsp file under WEB-INF/jsp folder.

hello.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<title>Hello World Spring Web MVC</title>
</head>
<body>
 <h2>${message}</h2>
</body>
</html>

Create web.xml, HelloWorld-servlet.xml file under WEB-INF folder.

web.xml

<web-app id="WebApp_ID" version="2.4"
 xmlns="http://java.sun.com/xml/ns/j2ee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
   http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

 <display-name>Spring MVC Hello WorldApplication</display-name>

 <servlet>
  <servlet-name>HelloWorld</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <load-on-startup>1</load-on-startup>
 </servlet>

 <servlet-mapping>
  <servlet-name>HelloWorld</servlet-name>
  <url-pattern>/</url-pattern>
 </servlet-mapping>

</web-app>

HelloWorld-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:context="http://www.springframework.org/schema/context"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="
   http://www.springframework.org/schema/beans     
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/context 
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">

 <context:component-scan
  base-package="com.sample.myApp" />

 <bean
  class="org.springframework.web.servlet.view.InternalResourceViewResolver">
  <property name="prefix" value="/WEB-INF/jsp/" />
  <property name="suffix" value=".jsp" />
 </bean>

</beans>

Create index.jsp under webapp folder.

index.jsp

<html>
<body>
 <h2>Hello World!</h2>
</body>
</html>

Total project structure looks like below.

Run the application on server and hit any of below urls.

http://localhost:8080/springdemo/welcome

http://localhost:8080/springdemo/hari/welcome

http://localhost:8080/springdemo/hello

You will get the message 'Welcome to Spring MVC framework'.

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Monday, 19 November 2018

Spring mvc: SimpleUrlHandlerMapping annotation based configuration

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