How to make API calls using RestTemplate ?

Using RestTemplate

• Create a service / facade class to call the API.
• Inject new bean of RestTemplate (A Spring class) in this class using @Bean annotation.
• Call methods : getForObject, postForObject (Best one is to use exchange method)

Below example uses a global API available on internet for getting data.


@Component
public class EmployeeService {
    @Resource
    private RestTemplate restTemplate;

    private String baseUrl = "https://jsonplaceholder.typicode.com/";
   
    @Bean
    RestTemplate getRestTemplate() {
        return new RestTemplate();
    }
   
    public User getApiUsers() {
        User user = restTemplate.getForObject(baseUrl + "users/1", User.class);
        return user;
    }
}


Create required POJOs to hold data models
public class User {
    private Long id;
    private String name;
    private String username;
    private String email;

    // getters and setters
    // toString
}


Create Controller to inject and call the service to get API data
Used @RestController to expose API and provide request mapping
@RestController
@RequestMapping("emp")
public class EmpController {
    @Resource
    private EmployeeService employeeService;
   
    @GetMapping
    public User getUsers() {
        User user = employeeService.getApiUsers();
        System.out.println("USER : " + user);
        return user;
    }
}