Spring Data Rest web services for beginners - Step By Step Guide

This tutorial is designed for those who have not worked with the Spring Framework or rest web services before. I am keeping it simple and less verbose so that readers can easily follow the steps and start developing the restful web services using Spring Data Rest.

Spring Framework

is the trending and widely used J2EE frameworks. It has various modules for web development. In this tutorial, we will use the Spring Data Rest.

RESTful Web services

Representational State Transfer (REST)  is based on server-client architecture and uses the HTTP protocol(stateless protocol). CRUD operations can be easily mapped on HTTP methods

Create	POST
Read	GET
Update	PUT
Delete	Delete

Prerequisites for this tutorial

• Java 8 or later version
• Eclipse
• Maven

Let's start developing the RESTful web services

STEP 1

Open a new Maven Project in the eclipse, let's call it MyFirstRestApp. We will use the Spring Boot for this tutorial. Open the maven.xml file and add the following dependencies

	<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.techieshah</groupId>
	<artifactId>MyFirstRestApp</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>
	<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>2.0.5.RELEASE</version>
	</parent>
	<properties>
	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	</properties>
	<dependencies>
	<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-rest</artifactId>
	</dependency>
	<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-test</artifactId>
	<scope>test</scope>
	</dependency>
	</dependencies>
	</project>

view raw maven.xml hosted with ❤ by GitHub

STEP 2
Create the MyRestApplication.java file

	package com.techieshah;
	import org.springframework.boot.SpringApplication;
	import org.springframework.boot.autoconfigure.SpringBootApplication;
	@SpringBootApplication
	public class MyRestApplication {
	public static void main( String[] args ) {
	SpringApplication.run( MyRestApplication.class, args );
	}
	}

view raw MyRestApplication.java hosted with ❤ by GitHub

@SpringBootApplication is handling all the configurations behind the screen. It is equivalent to the following three configurations

1. @EnableAutoConfiguration
2. @ComponentScan
3. @Configuration

STEP 3

Now we will move to the Rest web services implementation. For simplicity, I am taking an example of Blog's posts. Create a BlogPostController.java file

	package com.techieshah;
	import java.util.ArrayList;
	import java.util.List;
	import org.springframework.web.bind.annotation.DeleteMapping;
	import org.springframework.web.bind.annotation.GetMapping;
	import org.springframework.web.bind.annotation.PathVariable;
	import org.springframework.web.bind.annotation.PostMapping;
	import org.springframework.web.bind.annotation.PutMapping;
	import org.springframework.web.bind.annotation.RequestBody;
	import org.springframework.web.bind.annotation.RequestMapping;
	import org.springframework.web.bind.annotation.RestController;
	import com.techieshah.domainmodel.BlogPost;
	@RestController
	@RequestMapping("/blogPosts")
	public class BlogPostController {
	private static List<BlogPost> blogPosts;
	static {
	blogPosts = new ArrayList<BlogPost>();
	blogPosts.add( new BlogPost( 1, "spring framework", "ws", "first example of rest web services" ) );
	blogPosts.add( new BlogPost( 2, "spring framework", "ws", "second example of rest web services" ) );
	}
	@GetMapping("")
	public List<BlogPost> all(){
	return blogPosts;
	}
	@GetMapping("/{id}")
	public BlogPost get(@PathVariable Integer id){
	for(BlogPost blogPost : blogPosts) {
	if(blogPost.id == id) {
	return blogPost;
	}
	}
	return null;
	}
	@PostMapping("")
	public String post(@RequestBody BlogPost blogPost){
	blogPosts.add(blogPost);
	return "Blog Post saved successfully";
	}
	@PutMapping("")
	public String put(@RequestBody BlogPost updatedBlogPost) {
	for(BlogPost blogPost : blogPosts) {
	if(blogPost.id == updatedBlogPost.id) {
	blogPost.name = updatedBlogPost.name;
	blogPost.tag = updatedBlogPost.tag;
	blogPost.content = updatedBlogPost.content;
	}
	}
	return "Blog Post updated successfully";
	}
	@DeleteMapping("{id}")
	public String delete(@PathVariable Integer id){
	for(BlogPost blogPost : blogPosts) {
	if(blogPost.id == id) {
	blogPosts.remove( blogPost );
	break;
	}
	}
	return "Blog Post deleted successfully";
	}
	}

view raw BlogPostController.java hosted with ❤ by GitHub

• @RestController tells the Spring framework that it is a RESTful web services resource. 
• @RequestMapping("/blogPosts") routes every request to /blogPosts to this class
• HTTP methods are routed to the respective operations using the @GetMapping,@PostMapping,@PutMapping and @DeleteMapping annotations.

STEP 4

Run the application as Java application from eclipse 

STEP 5

Now, let's test the application. We will use Postman ( a rest client) for this example. 

• Test the GET method

• Test the POST method

• Test the PUT method

• Test the Delete method

The full source code for this tutorial can be found at MyFirstRestApp .

You will find the following tutorial useful

A complete guide to securing Spring RESTful web services using HTTP Basic Authentication header

I hope that you found this tutorial useful. Please leave your feedback in the comments box below.