SpringBoot项目里面发起http请求的几种方法

在Spring Boot项目中发起HTTP请求的方法

在Spring Boot项目中，有几种常用的方式可以发起HTTP请求，以下是主要的几种方法：

1. 使用RestTemplate (Spring 5之前的主流方式)

// 需要先注入RestTemplate
@Autowired
private RestTemplate restTemplate;public void makeRequest() {// GET请求ResponseEntity<String> response = restTemplate.getForEntity("https://api.example.com/data", String.class);// POST请求HttpHeaders headers = new HttpHeaders();headers.setContentType(MediaType.APPLICATION_JSON);HttpEntity<String> request = new HttpEntity<>("{\"key\":\"value\"}", headers);ResponseEntity<String> response = restTemplate.postForEntity("https://api.example.com/data", request, String.class);
}

2. 使用WebClient (Spring 5+推荐的响应式方式)

// 需要添加spring-boot-starter-webflux依赖
WebClient webClient = WebClient.create();// GET请求
Mono<String> response = webClient.get().uri("https://api.example.com/data").retrieve().bodyToMono(String.class);// POST请求
Mono<String> response = webClient.post().uri("https://api.example.com/data").contentType(MediaType.APPLICATION_JSON).bodyValue("{\"key\":\"value\"}").retrieve().bodyToMono(String.class);

3. 使用HttpClient (Java 11+内置)

HttpClient client = HttpClient.newHttpClient();// GET请求
HttpRequest request = HttpRequest.newBuilder().uri(URI.create("https://api.example.com/data")).build();// POST请求
HttpRequest request = HttpRequest.newBuilder().uri(URI.create("https://api.example.com/data")).header("Content-Type", "application/json").POST(HttpRequest.BodyPublishers.ofString("{\"key\":\"value\"}")).build();// 发送请求
HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());

4. 使用Feign Client (声明式REST客户端)

// 需要添加spring-cloud-starter-openfeign依赖
@FeignClient(name = "exampleClient", url = "https://api.example.com")
public interface ExampleClient {@GetMapping("/data")String getData();@PostMapping("/data")String postData(@RequestBody String body);
}// 使用
@Autowired
private ExampleClient exampleClient;public void makeRequest() {String response = exampleClient.getData();
}

5. 使用第三方库如OkHttp或Apache HttpClient

OkHttp示例:

OkHttpClient client = new OkHttpClient();// GET请求
Request request = new Request.Builder().url("https://api.example.com/data").build();// POST请求
RequestBody body = RequestBody.create("{\"key\":\"value\"}", MediaType.parse("application/json"));
Request request = new Request.Builder().url("https://api.example.com/data").post(body).build();// 发送请求
Response response = client.newCall(request).execute();

Apache HttpClient示例:

CloseableHttpClient httpClient = HttpClients.createDefault();// GET请求
HttpGet httpGet = new HttpGet("https://api.example.com/data");// POST请求
HttpPost httpPost = new HttpPost("https://api.example.com/data");
StringEntity entity = new StringEntity("{\"key\":\"value\"}");
httpPost.setEntity(entity);
httpPost.setHeader("Content-type", "application/json");// 发送请求
CloseableHttpResponse response = httpClient.execute(httpPost);