Spring Boot REST Client

Calling External REST APIs in Spring Boot

Spring Boot simplifies calling external REST APIs using RestTemplate or WebClient. RestTemplate is simpler for basic needs, while WebClient offers more advanced features like reactive programming.

RestTemplate (synchronous):

@Autowired
RestTemplate restTemplate;

public String fetchDataFromExternalAPI(String url) {
    ResponseEntity<String> response = restTemplate.getForEntity(url, String.class);
    return response.getBody();
}

WebClient (reactive):

@Autowired
WebClient webClient;

public Mono<String> fetchDataFromExternalAPI(String url) {
    return webClient.get()
            .uri(url)
            .retrieve()
            .bodyToMono(String.class);
}

Error Handling: Wrap calls in try-catch (RestTemplate) or use .onErrorResume (WebClient) for robust error handling. Consider using a custom exception handler for better management.

Dependency: Add spring-boot-starter-web to your pom.xml for both. For reactive approach, you'll also need spring-webflux.

Choosing the right approach: Use RestTemplate for simple synchronous calls; WebClient for asynchronous, non-blocking operations and better handling of large datasets. Remember to handle potential exceptions gracefully. Always consider security aspects like authentication and authorization when interacting with external APIs.