[JAVA] Hello World with Spring Boot

environment

Mac Mojave 10.14.5
IntelliJ IDEA
JDK 1.8
Gradle

Creating a project

First, create a project. Click ** Create New Project **. スクリーンショット 2019-06-07 21.51.15.png

Select ** Gradle ** and ** JDK ** and press ** Next **. スクリーンショット 2019-06-07 22.01.05.png

Enter the ** Group ID ** and ** Artifact ID ** and press ** Next **. ・ Group ID: HelloWorld -Artif ID: HelloWorld スクリーンショット 2019-06-07 22.16.43.png

When saving, check ** Use automatic import ** and press ** Next ** so that Gradle will automatically resolve the dependency. スクリーンショット 2019-06-07 22.16.51.png

Enter the ** project name ** and press ** Done **. ・ Project name: Hello World

If the following pop-up appears, press ** Allow **. スクリーンショット 2019-06-07 22.17.25.png

Creating an application

Now, let's write a program that actually displays Hello World on the browser using Spring Boot.

Right-click (project Root) / src / main / java and create a new class. Specify the class in the name, including the package name separated by. (Dot). ** Name: ** jp.example.Application

Since an error occurs when importing, the dependency is resolved. スクリーンショット 2019-06-08 15.34.59.png

`build.gradle`


plugins {
    id 'java'
}

group 'HelloWorld'
version '1.0-SNAPSHOT'

sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.12'
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-web', version: '2.1.3.RELEASE'
}

I will write the product code.

`Application.java`


package jp.co.example;

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);
    }
}

`HelloController`


package jp.co.example;

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

@RestController
public class HelloController {
    @RequestMapping("/")
    public static String Hello(){
        return "Hello World!";
    }
}

Execute and access the following address. http://localhost:8080/

It is OK if the returned character string is output on the browser.