Spring: openAPI: Hello world application

Follow below step-by-step procedure to build simple hello world application.

 

Step 1: Create new maven project ‘openapi-hello-world’.

 

Step 2: Update pom.xml with maven dependencies.

 

pom.xml

<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>
	<groupId>com.sample.app</groupId>
	<artifactId>openapi-hello-world</artifactId>
	<version>1</version>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.6.4</version>
	</parent>

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


		<dependency>
			<groupId>org.springdoc</groupId>
			<artifactId>springdoc-openapi-ui</artifactId>
			<version>1.6.6</version>
		</dependency>


	</dependencies>
</project>

 

Step 3: Define Employee model class.

 

Employee.java

 

package com.sample.app.model;

public class Employee {
	private int id;
	private String firstName;
	private String lastName;
	
	public Employee() {}

	public Employee(int id, String firstName, String lastName) {
		super();
		this.id = id;
		this.firstName = firstName;
		this.lastName = lastName;
	}

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getFirstName() {
		return firstName;
	}

	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}

	public String getLastName() {
		return lastName;
	}

	public void setLastName(String lastName) {
		this.lastName = lastName;
	}

	@Override
	public String toString() {
		StringBuilder builder = new StringBuilder();
		builder.append("Employee [id=").append(id).append(", firstName=").append(firstName).append(", lastName=")
				.append(lastName).append("]");
		return builder.toString();
	}

}

 

Step 4: Define EmployeeRepository.

 

EmployeeRepository.java

 

package com.sample.app.repository;

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

import org.springframework.stereotype.Repository;

import com.sample.app.model.Employee;

@Repository
public class EmployeeRepository {

	private static final List<Employee> emps = new ArrayList<>();

	static {
		Employee emp1 = new Employee(1, "Sunil", "Dayanand");
		Employee emp2 = new Employee(2, "Keerthi", "Shetty");
		Employee emp3 = new Employee(3, "Ram", "Anand");

		emps.add(emp1);
		emps.add(emp2);
		emps.add(emp3);

	}

	public List<Employee> all() {
		return emps;
	}

	public Employee add(Employee emp) {
		emps.add(emp);
		return emp;
	}

}

 

Step 5: Define EmployeeController.

 

EmployeeController.java

 

package com.sample.app.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.sample.app.model.Employee;
import com.sample.app.repository.EmployeeRepository;

@RestController
@RequestMapping("api/v1/employees")
public class EmployeeController {

	@Autowired
	private EmployeeRepository empRepo;

	@RequestMapping(method = RequestMethod.GET)
	public ResponseEntity<List<Employee>> all() {
		return ResponseEntity.ok(empRepo.all());
	}

	@RequestMapping(method = RequestMethod.POST)
	public ResponseEntity<Employee> create(@RequestBody Employee emp) {
		Employee persistedEmp = empRepo.add(emp);

		return ResponseEntity.status(HttpStatus.CREATED).body(persistedEmp);

	}
}

 

Step 6: Define main application class.

 

App.java

 

package com.sample.app;

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

@SpringBootApplication
public class App {
	public static void main(String[] args) {

		SpringApplication.run(App.class, args);

	}
}

 

Total project structure looks like below.

 

 

Run App.java and open the url ‘http://localhost:8080/swagger-ui/index.html’ to see the REST APIs.

 

 

You can download complete working application from this link.

 

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