Spring Boot @ResponseBody - Creating Controller Return Values to Response Body

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In this short article, we will learn how to use Spring Boot @ResponseBody annotation in a controller to write data to the body of the response object. We create a Spring Boot RESTful application to demonstrate the annotation.

Spring @ResponseBody

@ResponseBody is a Spring annotation which binds a method return value to the web response body. It is not interpreted as a view name. It uses HTTP Message converters to convert the return value to HTTP response body, based on the content-type in the request HTTP header.

Here is a sample code snippet:

 @ResponseBody @GetMapping(path = "/users") public List<User> home() { return Arrays.asList(new User(1, "Ramesh"), new User(2, "Prabhas"), new User(3, "John"), new User(4, "Tony"), new User(4, "Tom")); }

Spring Boot @ResponseBody Annotation Example

The following example creates a Spring Boot web application that returns JSON data to the client.

Development Steps

1. Create a Spring Boot Application
2. Project Structure
3. Pom Dependencies
4. Java Bean - User.java
5. Create REST Controller - UserController.java
6. Run Application - Application.java

1. Create a Spring Boot Application

There are many ways to create a Spring Boot application. You can refer below articles to create a Spring Boot application.

>> Create Spring Boot Project With Spring Initializer
>> Create Spring Boot Project in Spring Tool Suite [STS]

Refer project structure or packaging structure in the next step.

2. Project Structure

This is the project structure of the Spring Boot application that we are going to create - 

3. Pom Dependencies

This is the Maven build file. The spring-boot-starter-web is a starter for building web applications using Spring MVC. It uses Tomcat as the default embedded container.

<?xml version="1.0" encoding="UTF-8"?> <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> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.5.RELEASE</version> <relativePath /> <!-- lookup parent from repository --> </parent> <groupId>net.javaguides.springboot</groupId> <artifactId>springboot-annotations-demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>springboot-annotations-demo</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>

4. Java Bean - User.java

Let's create a representation class which we use to return in JSON format:

package net.javaguides.springboot; public class User { private Integer id; private String name; public User() {} public User(Integer id, String name) { this.id = id; this.name = name; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } }

5. Create REST Controller - UserController.java

Let's create a simple UserController with users rest API which returns a list of users in JSON format.

package net.javaguides.springboot; import java.util.Arrays; import java.util.List; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.ResponseBody; @Controller public class UserController { @ResponseBody @GetMapping(path = "/users") public List < User > home() { return Arrays.asList(new User(1, "Ramesh"), new User(2, "Prabhas"), new User(3, "John"), new User(4, "Tony"), new User(4, "Tom")); } }

6. Run Application - Application.java

Application is the entry point that sets up the Spring Boot application. The @SpringBootApplication annotation enables auto-configuration and component scanning.

Let's run this Spring boot application from either Eclipse IDE by right click - Run As - Java Application.

Or you can use the below maven command to run:

mvn spring-boot:run

7. Testing from Browser

Hit this URL in a browser - http://localhost:8080/users

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