@Rest Controller Example

User.java

package GradleDemo;

import java.util.Date;

public class User {
	private Integer id;
	private String name;
	private Date bithDate;
	
	public User() {
		
	}
	
	public User(Integer id, String name, Date bithDate) {
		super();
		this.id = id;
		this.name = name;
		this.bithDate = bithDate;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Date getBithDate() {
		return bithDate;
	}
	public void setBithDate(Date bithDate) {
		this.bithDate = bithDate;
	}
	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + ", bithDate=" + bithDate + "]";
	}
}

UserDaoService.java

package GradleDemo;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import org.springframework.stereotype.Component;

@Component
public class UserDaoService {
	public static int userCount = 3;
	private static List<User> users = new ArrayList<>();
	static {
		users.add(new User(1,"Tyson",new Date()));
		users.add(new User(2,"Justin",new Date()));
		users.add(new User(3,"Martin",new Date()));
	}
	
	public List<User> findAll(){
		return users;
	}
	
	public User save(User user) {
		if(user.getId()==null) {
			user.setId(++userCount);
		}
		users.add(user);
		return user;
	}
	public User findOne(int id) {
		for(User user : users) {
			if(user.getId()==id) {
				return user;
			}
		}
		return null;
	}
}

UserResource.java

package GradleDemo;

import java.net.URI;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.support.ServletUriComponentsBuilder;

@RestController
public class UserResource {
	
	@Autowired
	private UserDaoService userDaoService; 
	
	@GetMapping("/users")
	public List<User> retrieveAllUsers(){
		return userDaoService.findAll();
	}
	
	@GetMapping("/user/{id}")
	public User getUser(@PathVariable int id) {
		return userDaoService.findOne(id);
	}
	
	@PostMapping("/users")
	public ResponseEntity<Object> createUser(@RequestBody User user) {
		User savedUser = userDaoService.save(user);
		URI location = ServletUriComponentsBuilder
				.fromCurrentContextPath()
				.path("{id}")
				.buildAndExpand(savedUser.getId()).toUri();
		return ResponseEntity.created(location).build(); // 201 response is returned
	}
}

App.java

package GradleDemo;

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

@SpringBootApplication
public class App {

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

build.gradle

plugins {
    id 'java'
    id 'org.springframework.boot' version '2.2.1.RELEASE'
    id 'io.spring.dependency-management' version '1.0.8.RELEASE'
}

repositories {
    mavenCentral()
}

dependencies {
    implementation 'com.google.guava:guava:28.0-jre'
    testImplementation 'junit:junit:4.12'
    implementation 'org.springframework.boot:spring-boot-dependencies:2.2.1.RELEASE'
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.boot:spring-boot-starter-actuator'
    implementation 'org.springframework.data:spring-data-rest-hal-browser'
	implementation 'org.springframework.boot:spring-boot-devtools:1.3.0.RELEASE'
	implementation 'org.springframework.data:spring-data-jpa:2.2.2.RELEASE'
	implementation 'javax.persistence:javax.persistence-api:2.2'
	implementation 'com.h2database:h2:1.4.200'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'

    components {
        withModule('org.springframework:spring-beans') {
            allVariants {
                withDependencyConstraints {
                    it.findAll { it.name == 'snakeyaml' }.each { it.version { strictly '1.19' } }
                }
            }
        }
    }
}

bootJar {
    mainClassName = 'GradleDemo.App'
}

task runJar{
	dependsOn 'assemble'
	dependsOn 'jar'
	doLast{
  		javaexec { 
    		main="-jar";
    		args = [
            	"build/libs/"+rootProject.name+".jar"
           	]
		} 
	}
}