set up java spring boot "hello world" web application on ubuntu from zero.

install JDK 8

$ sudo apt-get install openjdk-8-jdk

install Gradle

$ curl -s "https://get.sdkman.io" | bash
$ source "$HOME/.sdkman/bin/sdkman-init.sh"
$ sdk install gradle 5.1.1

Spring Initializr

start.spring.io
get your "demo.zip" and unzip it.
choose "Gradle Project",
please remember add "Web" as dependence,
otherwise there will be compile errors.

Create a simple web application
$ cat src/main/java/com/example/demo/HelloController.java

package com.example.demo;

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

@RestController
public class HelloController {

    @RequestMapping("/")
    public String index() {
        return "Greetings from Spring Boot!";
    }

}

Run the Application

$ ./gradlew bootRun

Check out the service.

$ curl localhost:8080
Greetings from Spring Boot!

Generate IDE profile

add two plugin in build.gradle

apply plugin "idea" apply plugin "eclipse" 

generate IDE profile for IntelliJ IDEA(ipr)
./gradlew idea
generate IDE profile for Eclipse(.project)
./gradlew eclipse

Refers

Building an Application with Spring Boot