Developing REST Service using Spring Boot



Overview

The tutorial will show, how to develop a REST API with Spring. We’ll look into the Spring Boot solution for creating the application.

We’ll primarily use Java configuration in this tutorial.

Pre-requisties

  • JDK 1.8
  • Maven
  • IDE (for ease of use)

Setup maven project

Creat a maven project and add the required dependencies and plugins in pom.xml

We will use the dependencyManagement to define a standard version of an artifact to use across multiple projects.

We will allow spring-boot-starter-parent to manage the version of the artifacts.

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<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.3.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>

Now we’ll add the spring-boot-starter-web dependency.

Spring Boot Starter Web includes:

  • spring-web module
  • spring-webmvc module
  • tomcat starter

Spring-web & Spring-webmvc are required for spring appplication while tomcat starter is required to run web application directly without explicitly installing any server.

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<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>

Spring Boot Maven Plugin provides Spring Boot support in Maven, letting you package executable jar or war archives and run an application “in-place”.

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<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

Creating a Spring Boot Application

Create a class with main method. Annotate the class with @SpringBootApplication. Call the run method of SpringApplication class

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package com.tutorialflix.spring.web;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringBootWebApplication {

public static void main(String[] args) {
SpringApplication.run(SpringBootWebApplication.class, args);
}
}

@SpringBootApplication includes the functionality of following annotations:

  • @Configuration
  • @EnableAutoConfiguration
  • @ComponentScan.

By default, it will perform the component scan in base package. So make sure SpringBootWebApplication class is present in the base package.

Creating a REST Controller

Create a class with a meaningful name based on your requirement & annotate the class with @RestController. The @RestController is the central artifact in the entire Web Tier of the RESTful API.

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package com.tutorialflix.spring.web.contrroller;

import org.springframework.stereotype.RestController;

@RestController
public class MyRestController {


}

Create a GET method to accept requests

Create a method named home to accept the request on ‘/‘ url and show the index.html

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@GetMapping("/sayHello")
public Map<String,String> sayHello() {
Map map = new HashMap<>();
map.put("response","Hello, how are you");
return map;

Create a POST method to accept requests

Create a method named home to accept the request on ‘/‘ url and show the index.html

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@PostMapping("/sayHelloWithName")
public Map<String,String> sayHelloWithName(Map<String,String> request) {
Map map = new HashMap<>();
map.put("response","Hello, how are you " + request.get("name"));
return map;
}

Configuration using properties file

Create a file application.properties inside resources folder of application and following properties.

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server.port=8081
logging.level.org.springframework.web=DEBUG

server.port : to change the default port 8080 to any other port number.

logging.level.org.springframework.web : to change the log level default INFO to DEBUG

Run the REST API

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$ mvn spring-boot:run

Test

Goto http://localhost:8081/

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