Tuesday, January 24, 2017

Spring MVC - Generate JSON Example

The following example show how to generate JSON using Spring Web MVC framework. To start with it, let us have working Eclipse IDE in place and follow the following steps to develop a Dynamic Form based Web Application using Spring Web Framework:

StepDescription
1Create a project with a name TestWeb under a package com.tutorialspoint as explained in the Spring MVC - Hello World Example chapter.
2Create a Java classes User, UserController under the com.tutorialspoint package.
3Download Jackson libraries Jackson Core, Jackson Databind and Jackson Annotations from maven repository page. Put them in your CLASSPATH.
4The final step is to create the content of all the source and configuration files and export the application as explained below.
User.java
package com.tutorialspoint;

public class User {
   private String name;
   private int id;
   public String getName() {
      return name;
   }  
   public void setName(String name) {
      this.name = name;
   }
   public int getId() {
      return id;
   }   
   public void setId(int id) {
      this.id = id;
   } 
}
UserController.java
package com.tutorialspoint;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping("/user")
public class UserController {
 
   @RequestMapping(value="{name}", method = RequestMethod.GET)
   public @ResponseBody User getUser(@PathVariable String name) {

      User user = new User();

      user.setName(name);
      user.setId(1);
      return user;
   }
}
TestWeb-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"
   xmlns:mvc="http://www.springframework.org/schema/mvc"
   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
   http://www.springframework.org/schema/mvc
   http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
   <context:component-scan base-package="com.tutorialspoint" />
   <mvc:annotation-driven />
</beans>
Here we've created a Simple POJO User and in UserController we've return the User. Spring automatically handles the JSON conversion based on RequestMapping and Jackson jar present in classpath.
Once you are done with creating source and configuration files, export your application. Right click on your application and use Export > WAR File option and save your TestWeb.war file in Tomcat's webapps folder.
Now start your Tomcat server and make sure you are able to access other web pages from webapps folder using a standard browser. Now try a URL http://localhost:8080/TestWeb/mahesh and you should see the following result.
Spring JSON Generation

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