Spring boot REST: Send json response of an object

Spring boot has default support for JSON payload. For example, below snippet return all the employees data in json format.

@RequestMapping(value = "employees", method = RequestMethod.GET)

public ResponseEntity<List<Employee>> all() {

         return ResponseEntity.ok(empRepo.all());

}

Find the below working application.

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);

 }
}

EmployeeController.java

package com.sample.app.cotroller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
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/")
public class EmployeeController {

 @Autowired
 private EmployeeRepository empRepo;

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

HomeController.java

package com.sample.app.cotroller;

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

@RestController
public class HomeController {

 @RequestMapping("/")
 public String home() {
  return "Hello World";
 }
}

Employee.java

package com.sample.app.model;

public class Employee {
 private int id;
 private String firstName;
 private String lastName;

 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();
 }

}

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(1, "Keerthi", "Shetty");
  Employee emp3 = new Employee(1, "Ram", "Anand");
  
  emps.add(emp1);
  emps.add(emp2);
  emps.add(emp3);
  
 }
 
 public List<Employee> all(){
  return emps;
 }
 
}

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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>springRest</groupId>
  <artifactId>springRest</artifactId>
  <version>1</version>
  
  <parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>2.1.6.RELEASE</version>
 </parent>

 <name>springbootApp</name>
 <url>http://maven.apache.org</url>

 <properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 </properties>

 <dependencies>

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

 </dependencies>
</project>

Total project structure looks like below.

Run App.java.

Open the url ‘http://localhost:8080/api/v1/employees’ in browser, you can see below kind of screen.

You can download the complete working application from this link.

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