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    Developing REST Services using Spring Boot
    Published on: 6th October 2016
    Posted By: Amit Kumar

    This tutorial will provide you with steps to create Spring Web based REST services using Spring Boot.

    Abstract


    Spring Boot framework makes it easy to create standalone, production-ready Spring applications. It requires very minimal configuration and gets you started with minimum fuss as it manages the versions of third party dependent libraries for you.

    Spring Boot applications are easy to develop and deploy. It also helps you adopt Microservices like architecture by letting you build small standalone services that do not require any additional web/application servers. Web applications developed in Spring Boot contain embedded versions of servers that start and stop with your application. Spring Boot has support for Tomcat, Jetty and Undertow embedded servers, and can be extended to support others. 

    In simple terms, Spring Boot application is a simple Jar file that can easily be managed and migrated from one place to other. Spring Boot also comes with production-ready features such as metrics, health checks and externalised configuration.

    In this tutorial, we will be creating a simple Tutorial service using Spring Web framework in Spring Boot.

     

    Pre-requisites


    Here are the required softwares and skills required to build Tutorial service - 

    1. Java 8 or later
    2. Eclipse IDE with Maven and STS (Spring Tool Suite) plugin
    3. Basic knowledge of REST and Spring Core

     

    Developing REST Services using Spring Boot


     

    Creating a Spring Boot project

    We will be starting with creating a Spring Boot project called spring-boot-jaxrs-demo in Eclipse IDE using Spring Starter project wizard as follows -

    Spring Boot Web Demo Project Creation

     

    Click next to go to dependency page and select Jersey (JAX-RS) option from Web section as shown below -

    Spring Boot Web Demo Project Dependencies

     

    Click Finish to stop wizard and it will take some time to download dependencies. After it is over, you should see your project called spring-boot-web-demo in Eclipse Project Explorer.

    Although no changes are required in POM file, this is how it will look like (in case you want to copy dependencies manually) -

    <?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>
    
    	<groupId>com.aksain.microservices.springboot.basics</groupId>
    	<artifactId>spring-boot-web-demo</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>jar</packaging>
    
    	<name>spring-boot-web-demo</name>
    	<description>Demo project for Spring Boot</description>
    
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>1.4.1.RELEASE</version>
    		<relativePath/> <!-- lookup parent from repository -->
    	</parent>
    
    	<properties>
    		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    		<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>

     

    Develop local tutorial service

    Let's now create a local service with methods to return all tutorials or tutorial with provided id. We will simply be keeping all tutorials in a list of Tutorial objects and serve the request from here. Here is how our Tutorial domain object looks like - 

    package com.aksain.microservices.springboot.basics.models;
    
    /**
     * @author Amit Kumar
     *
     */
    public class Tutorial {
    	private Long id;
    	private String name;
    	private String description;
    	private Long categoryId;
    	private Long publisherId;
    
    	public Tutorial() {
    	}
    	
    	public Tutorial(Long id, String name, String description, Long categoryId, Long publisherId) {
    		this.id = id;
    		this.name = name;
    		this.description = description;
    		this.categoryId = categoryId;
    		this.publisherId = publisherId;
    	}
    	
    	/* (non-Javadoc)
    	 * @see java.lang.Object#hashCode()
    	 */
    	@Override
    	public int hashCode() {
    		final int prime = 31;
    		int result = 1;
    		result = prime * result + ((categoryId == null) ? 0 : categoryId.hashCode());
    		result = prime * result + ((description == null) ? 0 : description.hashCode());
    		result = prime * result + ((id == null) ? 0 : id.hashCode());
    		result = prime * result + ((name == null) ? 0 : name.hashCode());
    		result = prime * result + ((publisherId == null) ? 0 : publisherId.hashCode());
    		return result;
    	}
    
    	/* (non-Javadoc)
    	 * @see java.lang.Object#equals(java.lang.Object)
    	 */
    	@Override
    	public boolean equals(Object obj) {
    		if (this == obj)
    			return true;
    		if (obj == null)
    			return false;
    		if (getClass() != obj.getClass())
    			return false;
    		Tutorial other = (Tutorial) obj;
    		if (categoryId == null) {
    			if (other.categoryId != null)
    				return false;
    		} else if (!categoryId.equals(other.categoryId))
    			return false;
    		if (description == null) {
    			if (other.description != null)
    				return false;
    		} else if (!description.equals(other.description))
    			return false;
    		if (id == null) {
    			if (other.id != null)
    				return false;
    		} else if (!id.equals(other.id))
    			return false;
    		if (name == null) {
    			if (other.name != null)
    				return false;
    		} else if (!name.equals(other.name))
    			return false;
    		if (publisherId == null) {
    			if (other.publisherId != null)
    				return false;
    		} else if (!publisherId.equals(other.publisherId))
    			return false;
    		return true;
    	}
    
    	/**
    	 * @return the id
    	 */
    	public Long getId() {
    		return id;
    	}
    
    	/**
    	 * @param id the id to set
    	 */
    	public void setId(Long id) {
    		this.id = id;
    	}
    
    	/**
    	 * @return the name
    	 */
    	public String getName() {
    		return name;
    	}
    
    	/**
    	 * @param name the name to set
    	 */
    	public void setName(String name) {
    		this.name = name;
    	}
    
    	/**
    	 * @return the description
    	 */
    	public String getDescription() {
    		return description;
    	}
    
    	/**
    	 * @param description the description to set
    	 */
    	public void setDescription(String description) {
    		this.description = description;
    	}
    
    	/**
    	 * @return the categoryId
    	 */
    	public Long getCategoryId() {
    		return categoryId;
    	}
    
    	/**
    	 * @param categoryId the categoryId to set
    	 */
    	public void setCategoryId(Long categoryId) {
    		this.categoryId = categoryId;
    	}
    
    	/**
    	 * @return the publisherId
    	 */
    	public Long getPublisherId() {
    		return publisherId;
    	}
    
    	/**
    	 * @param publisherId the publisherId to set
    	 */
    	public void setPublisherId(Long publisherId) {
    		this.publisherId = publisherId;
    	}
    
    	/* (non-Javadoc)
    	 * @see java.lang.Object#toString()
    	 */
    	@Override
    	public String toString() {
    		return "Tutorial [id=" + id + ", name=" + name + ", description=" + description + ", categoryId=" + categoryId
    				+ ", publisherId=" + publisherId + "]";
    	}
    }
    

    And here is the complete code for our local TutorialService class - 

    package com.aksain.microservices.springboot.basics.services;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import javax.annotation.PostConstruct;
    
    import org.springframework.stereotype.Service;
    
    import com.aksain.microservices.springboot.basics.models.Tutorial;
    
    /**
     * @author Amit Kumar
     */
    @Service
    public class TutorialService {
    	
    	private final List<Tutorial> tutorials = new ArrayList<>();
    	
    	@PostConstruct
    	public void init() {
    		tutorials.add(new Tutorial(1l, "Tutorial1", "Tutorial 1 Description", 1l, 1l));
    		tutorials.add(new Tutorial(2l, "Tutorial2", "Tutorial 2 Description", 2l, 1l));
    		tutorials.add(new Tutorial(3l, "Tutorial3", "Tutorial 3 Description", 1l, 2l));
    		tutorials.add(new Tutorial(4l, "Tutorial4", "Tutorial 4 Description", 2l, 2l));
    	}
    	
    	public Tutorial getById(Long tutorialId) {
    		return tutorials.stream().filter((tutorial) -> tutorial.getId() == tutorialId).findFirst().get();
    	}
    	
    	public List<Tutorial> getAllTutorials() {
    		return tutorials;
    	}
    }

     

    Develop tutorial REST resource

    We will now leveage our local TutorialService to expose a REST resource TutorialResource as shown below -

    package com.aksain.microservices.springboot.basics.resources;
    
    import java.util.List;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.http.MediaType;
    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.RestController;
    
    import com.aksain.microservices.springboot.basics.models.Tutorial;
    import com.aksain.microservices.springboot.basics.services.TutorialService;
    
    /**
     * @author Amit Kumar
     */
    @RestController
    @RequestMapping("/tutorials")
    public class TutorialResource {
    
    	@Autowired
    	private TutorialService tutorialService;
    
    	@RequestMapping(method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    	public List<Tutorial> getById() {
    		return tutorialService.getAllTutorials();
    	}
    
    	@RequestMapping(value = "/{tutorialId}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    	public Tutorial getById(@PathVariable("tutorialId") final Long tutorialId) {
    		return tutorialService.getById(tutorialId);
    	}
    }

     

    Testing Tutorial Service


    Finally let's start our application so that we can test our tutorial service. Since it is a Spring Boot application, you don't need to deploy it to any web/application server.

    You can simply run SpringBootWebDemoApplication class like any other Java program. This will start embedded Tomcat server at port 8080 (you can also change port using server.port property in application.properties file).

     

    Once application has started successfully, open your favorite browser or REST client and make following call - 

    http://localhost:8080/tutorials

    Here is how REST service response should look like - 

    [{"id":1,"name":"Tutorial1","description":"Tutorial 1 Description","categoryId":1,"publisherId":1},{"id":2,"name":"Tutorial2","description":"Tutorial 2 Description","categoryId":2,"publisherId":1},{"id":3,"name":"Tutorial3","description":"Tutorial 3 Description","categoryId":1,"publisherId":2},{"id":4,"name":"Tutorial4","description":"Tutorial 4 Description","categoryId":2,"publisherId":2}]

     

    Simlarly, you can also try getting tutorials by an id as below - 

    http://localhost:8080/tutorials/3

    Here is what response will look like, this time - 

    {"id":3,"name":"Tutorial3","description":"Tutorial 3 Description","categoryId":1,"publisherId":2}

     

    Congratulations, you have successfully developed a simple REST service using Spring Web and Spring Boot.

     

    Thank you for reading through the tutorial. In case of any feedback/questions/concerns, you can communicate same to us through your comments and we shall get back to you as soon as possible.

    Posted By: Amit Kumar
    Published on: 6th October 2016

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