Developing REST Service using Spring Boot

Overview

In this tutorial, we'll learn, how to develop a REST API using the Spring Boot framework.

We’ll primarily use Java configuration in this tutorial.

Pre-requisties

JDK 1.8
Maven
IDE (for ease of use)

Setup maven project

Create 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.

<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.

<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”.

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
        </plugin>                     
    </plugins>
</build>

Creating a Spring Boot Application

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

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:

By default, it will perform the component scan in the 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.

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


    @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

    @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 the application and following properties.

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

$ mvn spring-boot:run

Test

Goto localhost:8081

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