Spring Boot Rest API Hello World Examples

Spring Boot Rest API Hello World Examples

Purpose: In this post, we will learn how we can create a simple spring boot API. The steps are given below.

1. Setup and Create Project: There is two way to create a new project.

a-: We can create a new project online following the link https://start.spring.io/.

Step. Select the project as a maven project.

Next Step. Select language as Java.

Next Step. Select Spring Boot version.

Next Step. Define project metadata.

Next Step. Select project package as Jar/ War.

Next Step. Select Java version.

Next Step. Add dependencies as you required.

Next Step. Generate project.

Next Step. Unzip downloaded file and Import in IDE as a maven project.

Next Step: Open IDE and Import project as a maven project.

Project Structure: Your project structure looks like as shown in the below image.

Next Step. Spring Boot Parent Dependencies.

  <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.0.M1</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>

Next Step. Project Dependencies.

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

Next Step. Spring Boot main class.

Class: Application.java

Note: @SpringBootApplication=@Configuration+ @EnableAutoConfiguration+ @ComponentScan.

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

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

Next Step. Create Rest Controller.

package com.bce.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloWorldRestController {

    @GetMapping
    public String hello() {
        return "Hello World";
    }

}

Next Step. Server Port:  The default server port is 8080. Wish you want to change open application.properties and add the below line.

server.port=8081

Next Step. Run the application. See demo below.

pom.xml

pom.xml looks like something as shown in the below code.

    <?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.0.M1</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.bce</groupId>
    <artifactId>spring-boot-example</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-boot-application</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>3.0.0</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.9.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </pluginRepository>
    </pluginRepositories>
</project>

Download Code from GitHub.  Source Code