@RestController and @Controller annotation example in Spring Boot

By
Rakesh
-

Here we will see @RestController and @Controller annotation example in Spring Boot.

Basic points about @RestController and @Controller annotation.

@RestController annotation.

  • This annotation introduced in Spring  4.0, available in org.springframework.web.bind.annotation package.
  • It has one optional element i.e value.
  • We use this annotation with the class.
  • This annotation is a combined form of @Controller and @ResponseBody
  • Internal implementation –
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Controller
@ResponseBody
public @interface RestController {
 

}

 

 @Controller annotation.

  • This annotation introduced in Spring 2.5, available in org.springframework.stereotype package.
  • It has one optional element i.e value.
  • We use this annotation with the class, in case of this annotation we need to use @ResponseBody explicitly.
  • Internal implementation –
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Controller {


}

 

Note –  What will happen if we use @RestController with the method or interface? With the method, it will give compilation error but if we use this annotation with an interface no compilation error. If we use @RestController with the interface then we need to provide corresponding implementation classes.

 

 

@RestController annotation example.

prerequisites –

  • JDK 1.8
  • Eclipse
  • maven
  • postman

Create maven project, Don’t forget to check ‘Create a simple project (skip)’click on next. Fill all details(GroupId – restcontrollerexample, ArtifactId – restcontrollerexample and name – restcontrollerexample) and click on finish. Keep packaging as the jar.

Make sure we have a correct 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>restcontrollerexample</groupId>
  <artifactId>restcontrollerexample</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>restcontrollerexample</name>
  
  <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.RELEASE</version>
 </parent>
  <dependencies>
	<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
       
        
   </dependencies>

    
   
</project>

 

Define Contoller(RestControllerExampleEndPoint.java), SpringBootMain(SpringRestControllerExample.java), and Entity class(Book.java).

RestControllerExampleEndPoint.java

package com.restcontroller;

import org.springframework.stereotype.Controller;
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.entity.Book;

@RestController
public class RestControllerExampleEndPoint {
	
	@RequestMapping(value = "/simpleuri",method = RequestMethod.GET)
    public Book getBook() {
    	Book book = new Book();
    	book.setBookId(109);
    	book.setBookName("book1");
    	book.setBookPrice("100");
      	
		return book;
	}
	
}

 

SpringRestControllerExample.java

package com.restcontroller;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class SpringRestControllerExample {
	public static void main(final String[] args) {
		final ConfigurableApplicationContext configurableApplicationContext = SpringApplication
				.run(SpringRestControllerExample.class, args);
		
		 
	}
	

}

Book.java

package com.entity;

public class Book {
	int bookId;
	String bookName;
	String bookPrice;
	public int getBookId() {
		return bookId;
	}
	public void setBookId(int bookId) {
		this.bookId = bookId;
	}
	public String getBookName() {
		return bookName;
	}
	public void setBookName(String bookName) {
		this.bookName = bookName;
	}
	public String getBookPrice() {
		return bookPrice;
	}
	public void setBookPrice(String bookPrice) {
		this.bookPrice = bookPrice;
	}
	

}

 

If you encounter any port related issue, define application.properties and change the port.

application.properties

server.port = 9093

 

Run the main class(SpringRestControllerExample.java).

 

 

Call rest URI(http://localhost:9093/simpleuri) from postman

 

@RestController and @Controller annotation example in Spring Boot

 

 

@Controller annotation example.

Let’s modify the controller class, we will not use @Responsebody annotation and see what happens.

package com.restcontroller;

import org.springframework.stereotype.Controller;
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.entity.Book;

@Controller
public class RestControllerExampleEndPoint {
	
	@RequestMapping(value = "/simpleuri",method = RequestMethod.GET)
    public Book getBook() {
    	Book book = new Book();
    	book.setBookId(109);
    	book.setBookName("book1");
    	book.setBookPrice("100");
    	return book;
	}
	
}

 

Run the main class and hit the rest URI from the postman.

 

 

Let’s use @ResponseBody with method or class.

package com.restcontroller;

import org.springframework.stereotype.Controller;
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.entity.Book;

@Controller
@ResponseBody
public class RestControllerExampleEndPoint {
	
	@RequestMapping(value = "/simpleuri",method = RequestMethod.GET)
    public Book getBook() {
    	Book book = new Book();
    	book.setBookId(109);
    	book.setBookName("book1");
    	book.setBookPrice("100");
    	return book;
	}
	
}

Again run the main class.

 

 

Yes, we have a response now.

That’s all about @RestController and @Controller annotation example in Spring Boot.

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