Home » Enterprise Java » spring » Spring @ResponseBody Annotation Example

About Yatin

Yatin
The author is graduated in Electronics & Telecommunication. During his studies, he has been involved with a significant number of projects ranging from programming and software engineering to telecommunications analysis. He works as a technical lead in the information technology sector where he is primarily involved with projects based on Java/J2EE technologies platform and novel UI technologies.

Spring @ResponseBody Annotation Example

Welcome readers, in this tutorial we will show how to implement the Spring @ResponseBody Annotation to return a Json response from a Spring Mvc Controller.

1. Introduction

1.1 Spring Framework

  • Spring is an open-source framework created to address the complexity of an enterprise application development
  • One of the chief advantages of the Spring framework is its layered architecture, which allows a developer to be selective about which of its components they can use while providing a cohesive framework for J2EE application development
  • Spring framework provides support and integration to various technologies for e.g.:
    • Support for Transaction Management
    • Support for interaction with the different databases
    • Integration with the Object Relationship frameworks for e.g. Hibernate, iBatis etc
    • Support for Dependency Injection which means all the required dependencies will be resolved with the help of containers
    • Support for REST style web-services

1.2 Spring Mvc Framework

Model-View-Controller (Mvc) is a well-known design pattern for designing the GUI based applications. It mainly decouples the business logic from UI by separating the roles of Model, View, and Controller in an application. This pattern divides the application into three components to separate the internal representation of the information from the way it is being presented to the user. The three components are:

  • Model (M): Model’s responsibility is to manage the application’s data, business logic, and the business rules. It is a POJO class which encapsulates the application data given by the controller
  • View (V): A view is an output representation of the information, such as displaying information or reports to the user either as a text-form or as charts. Views are usually the JSP templates written with Java Standard Tag Library (JSTL)
  • Controller (C): Controller’s responsibility is to invoke the Models to perform the business logic and then update the view based on the model’s output. In the spring framework, the controller part is played by the Dispatcher Servlet
Spring @ResponseBody Annotation - Model View Controller (MVC) Overview

Fig. 1: Model View Controller (MVC) Overview

Now, open up the Eclipse IDE and let us see how to implement this tutorial.

2. Spring @ResponseBody Annotation Example

Here is a systematic guide for implementing this tutorial in the Spring Mvc framework.

2.1 Tools Used

We are using Eclipse Kepler SR2, MySQL, JDK 8 and Maven. Having said that, we have tested the code against JDK 1.7 and it works well.

2.2 Project Structure

Firstly, let us review the final project structure, in case you are confused about where you should create the corresponding files or folder later!

Spring @ResponseBody Annotation - Application Project Structure

Fig. 2: Application Project Structure

2.3 Project Creation

This section will demonstrate how to create a Java-based Maven project with Eclipse. In Eclipse IDE, go to File -> New -> Maven Project.

Spring @ResponseBody Annotation - Create a Maven Project

Fig. 3: Create a Maven Project

In the New Maven Project window, it will ask you to select project location. By default, ‘Use default workspace location’ will be selected. Just click on next button to proceed.

Spring @ResponseBody Annotation - Project Details

Fig. 4: Project Details

Select the Maven Web App archetype from the list of options and click next.

Spring @ResponseBody Annotation - Archetype Selection

Fig. 5: Archetype Selection

It will ask you to ‘Enter the group and the artifact id for the project’. We will input the details as shown in the below image. The version number will be by default: 0.0.1-SNAPSHOT.

Spring @ResponseBody Annotation - Archetype Parameters

Fig. 6: Archetype Parameters

Click on Finish and the creation of a maven project is completed. If you observe, it has downloaded the maven dependencies and a pom.xml file will be created. It will have the following code:

pom.xml

<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/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.spring.mvc</groupId>
	<artifactId>SpringResponseBodyAnnotation</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>
</project>

Developers can start adding the dependencies they want like Servlet API, Spring Mvc. Let us start building the application!

3. Application Building

Below are the steps involved in developing this application.

3.1 Maven Dependencies

Here, we specify the dependencies for the spring mvc framework. The rest dependencies such as Jackson API, Spring Beans, Spring Core etc. will be automatically resolved by Maven. The updated file will have the following code:

pom.xml

<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.spring.mvc</groupId>
	<artifactId>SpringResponseBodyAnnotation</artifactId>
	<packaging>war</packaging>
	<version>0.0.1-SNAPSHOT</version>
	<name>SpringResponseBodyAnnotation Maven Webapp</name>
	<url>http://maven.apache.org</url>
	<dependencies>
		<!-- Servlet API Dependency -->
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>servlet-api</artifactId>
			<version>3.0-alpha-1</version>
		</dependency>
		<!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>5.0.8.RELEASE</version>
		</dependency>
		<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-databind</artifactId>
			<version>2.9.6</version>
		</dependency>
	</dependencies>
	<build>
		<finalName>SpringResponseBodyAnnotation</finalName>
	</build>
</project>

3.2 Configuration Files

Let us write all the configuration files involved in this application.

3.2.1 Web Deployment Descriptor

The web.xml file declares one servlet (i.e. Dispatcher Servlet) to receive all kind of the requests. Dispatcher servlet here acts as a front controller. Add the following code to it:

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 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_2_5.xsd">

	<display-name>SpringResponseBodyAnnotation</display-name>

	<servlet>
		<servlet-name>responsebodydispatcher</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>responsebodydispatcher</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
</web-app>

3.2.2 Spring Configuration File

To configure the spring framework, developers need to implement a bean configuration file i.e. responsebodydispatcher-servlet.xml which provide an interface between the basic Java class and the outside world. Put this XML file in the SpringResponseBodyAnnotation/src/main/webapp/WEB-INF folder and add the following code to it:

responsebodydispatcher-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xsi:schemaLocation="
        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
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">

	<context:annotation-config />

	<!-- for the stereotype annotation to work -->
	<context:component-scan base-package="com.spring.mvc.controller" />
	<context:component-scan base-package="com.spring.mvc.component" />

	<mvc:annotation-driven />
</beans>

3.3 Java Class Creation

Let us write the Java classes involved in this application.

3.3.1 Model Class

This pojo class defines company bean. Add the following code to it:

MyCompany.java

package com.spring.mvc.component;

import org.springframework.stereotype.Component;

@Component
public class MyCompany {

	private int id;
	private String fullname;
	private String email;

	public MyCompany() { }

	public MyCompany(int id, String fullname, String email) {		
		this.id = id;
		this.fullname = fullname;
		this.email = email;
	}

	public int getId() {
		return id;
	}

	public String getFullname() {
		return fullname;
	}

	public String getEmail() {
		return email;
	}
}

3.3.2 Controller Class

Let us create a simple class where the @RestController annotation specifies this class as a spring controller and is responsible for handling the incoming requests. In here,

  • The controller methods are annotated with the @ResponseBody annotation which binds the return value to a web response body.
    • The response is not interpreted as a view-name
    • The annotation uses the HTTP message converters to convert the return value to the HTTP request body, based on the content-type in the HTTP request header
  • The controller methods are mapped to HTTP GET request which fetches the resources

Add the following code to it:

MyCtrl.java

package com.spring.mvc.controller;

import java.util.ArrayList;
import java.util.List;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.spring.mvc.component.MyCompany;

@RestController
public class MyCtrl {

	@RequestMapping(value="/company", method=RequestMethod.GET)
	public @ResponseBody MyCompany getCompany() {

		return new MyCompany(12, "John Greece", "john.greece@test.com");
	}

	@RequestMapping(value="/companies", method=RequestMethod.GET)
	public @ResponseBody List<MyCompany> getCompanies() {

		List<MyCompany> companies = new ArrayList<MyCompany>();		
		companies.add(new MyCompany(3, "Andrew Strauss", "andrew.strauss@test.com"));		
		companies.add(new MyCompany(12, "John Greece", "john.greece@test.com"));
		companies.add(new MyCompany(101, "Robert Parera", "robert.parera@test.com"));
		companies.add(new MyCompany(153, "Charlotte O' Neil", "charlotte.neil@test.com"));
		companies.add(new MyCompany(239, "Eddy Knight", "eddy.knight@test.com"));

		return companies;
	}
}

4. Run the Application

As we are ready with all the changes, let us compile the project and deploy the application on the Tomcat7 server. To deploy the application on Tomat7, right-click on the project and navigate to Run as -> Run on Server.

Spring @ResponseBody Annotation - Deploy Application on Tomcat

Fig. 8: How to Deploy Application on Tomcat

Tomcat will deploy the application in its web-apps folder and shall start its execution to deploy the project so that we can go ahead and test it on the browser.

5. Project Demo

We will test this sample application using a GUI based client. Launch the Postman tool and hit the different URL’s to fetch the data and display the results in the JSON format.

5.1 Get all Companies

Hit the following HTTP GET URL in the Postman tool to display the list of companies in the Json format.

http://localhost:8088/SpringResponseBodyAnnotation/companies

Java object’s list as Json response

[
    {
        "id": 3,
        "fullname": "Andrew Strauss",
        "email": "andrew.strauss@test.com"
    },
    {
        "id": 12,
        "fullname": "John Greece",
        "email": "john.greece@test.com"
    },
    {
        "id": 101,
        "fullname": "Robert Parera",
        "email": "robert.parera@test.com"
    },
    {
        "id": 153,
        "fullname": "Charlotte O' Neil",
        "email": "charlotte.neil@test.com"
    },
    {
        "id": 239,
        "fullname": "Eddy Knight",
        "email": "eddy.knight@test.com"
    }
]

5.2 Get Company

Hit the following HTTP GET URL in the Postman tool to display the Java object as Json response.

http://localhost:8088/SpringResponseBodyAnnotation/company

Java Object as Json response

{
    "id": 12,
    "fullname": "John Greece",
    "email": "john.greece@test.com"
}

Do note, server name (localhost) and port (8088) may vary as per your tomcat configuration. That is all for this tutorial and I hope the article served you whatever you were looking for. Happy Learning and do not forget to share!

6. Conclusion

In this section, developers learned how to implement the @ResponseBody annotation in the spring framework. Developers can download the sample application as an Eclipse project in the Downloads section.

7. Download the Eclipse Project

This was an example of the @ResponseBody annotation in the Spring Mvc framework.

Download
You can download the full source code of this example here: SpringResponseBodyAnnotation
(No Ratings Yet)
1 Comment Views Tweet it!

Do you want to know how to develop your skillset to become a Java Rockstar?

Subscribe to our newsletter to start Rocking right now!

To get you started we give you our best selling eBooks for FREE!

 

1. JPA Mini Book

2. JVM Troubleshooting Guide

3. JUnit Tutorial for Unit Testing

4. Java Annotations Tutorial

5. Java Interview Questions

6. Spring Interview Questions

7. Android UI Design

 

and many more ....

 

Receive Java & Developer job alerts in your Area

 

1
Leave a Reply

avatar
1 Comment threads
0 Thread replies
0 Followers
 
Most reacted comment
Hottest comment thread
1 Comment authors
Andre Kapp Recent comment authors
  Subscribe  
newest oldest most voted
Notify of
Andre Kapp
Guest
Andre Kapp

Use SpringBoot and save yourself a LOT of configuration. No web.xml, etc, etc.