Three Ways to Call External APIs in Spring Boot: HttpClient, RestTemplate, and Feign

The article introduces three approaches for accessing external interfaces within a Spring Boot project, each with its own code sample and usage notes.

1. Raw HttpClient – Shows a manual HTTP request using CloseableHttpClient client = HttpClients.createDefault(); with token header, JSON body creation, and response parsing.

2. RestTemplate – Demonstrates how to use Spring's RestTemplate for GET and POST calls, including getForEntity, getForObject, and postForEntity overloads, request entity construction, and handling of JSON payloads.

3. Feign – Details adding the Feign dependency, enabling it with @EnableFeignClients, defining a Feign client interface with @FeignClient, and configuring request headers via a custom RequestInterceptor implementation to inject tokens.

Additional sections cover Maven dependency snippets, application entry‑point annotations, and example controller/service code for both standard and token‑aware Feign calls. The article also includes brief notes on testing with Postman and promotional messages unrelated to the technical content.