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Consuming REST Services

When your Spring Boot backend needs to fetch external data from a third-party API (like triggering a Stripe payment), it must act as a client.

OpenFeign​

OpenFeign is a declarative HTTP client developed by Netflix. Instead of manually writing HTTP connection strings, you declare an interface, and Spring generates the actual network logic.

@FeignClient(name = "userClient", url = "https://jsonplaceholder.typicode.com")
public interface UserClient {
    
    @GetMapping("/users/{id}")
    User fetchRemoteUser(@PathVariable("id") Long id);
}

RestTemplate​

RestTemplate is the legacy synchronous HTTP client found in standard Spring Web. It executes blocking requests.

@Service
public class MetricService {
    public void getMetrics() {
        RestTemplate restTemplate = new RestTemplate();
        String result = restTemplate.getForObject("http://api.example.com/data", String.class);
        System.out.println(result);
    }
}