java HTTP请求头怎么加

在 Java 里“加 HTTP 请求头”取决于你用的是什么方式发请求。下面给你几种常见场景和写法，直接对照用就行。

一、使用 HttpURLConnection（JDK 原生）

URL url = new URL("https://example.com/api");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();

// 加请求头
conn.setRequestProperty("Authorization", "Bearer token123");
conn.setRequestProperty("Content-Type", "application/json");

conn.setRequestMethod("GET");
conn.connect();

✅ 适合：简单请求、不引入第三方库

二、使用 HttpClient（Java 11+ 推荐）

HttpClient client = HttpClient.newHttpClient();

HttpRequest request = HttpRequest.newBuilder()
        .uri(URI.create("https://example.com/api"))
        .header("Authorization", "Bearer token123")
        .header("Content-Type", "application/json")
        .GET()
        .build();

HttpResponse<String> response =
        client.send(request, HttpResponse.BodyHandlers.ofString());

✅ 适合：现代 Java 项目（推荐）

三、使用 OkHttp（最常用第三方库）

OkHttpClient client = new OkHttpClient();

Request request = new Request.Builder()
        .url("https://example.com/api")
        .addHeader("Authorization", "Bearer token123")
        .addHeader("Content-Type", "application/json")
        .build();

Response response = client.newCall(request).execute();

✅ 适合：Android / 网络请求频繁项目

四、使用 Spring RestTemplate

HttpHeaders headers = new HttpHeaders();
headers.set("Authorization", "Bearer token123");
headers.setContentType(MediaType.APPLICATION_JSON);

HttpEntity<String> entity = new HttpEntity<>(null, headers);

RestTemplate restTemplate = new RestTemplate();
ResponseEntity<String> response =
        restTemplate.exchange(
                "https://example.com/api",
                HttpMethod.GET,
                entity,
                String.class
        );

五、使用 Spring WebClient（响应式）

WebClient client = WebClient.builder().build();

client.get()
      .uri("https://example.com/api")
      .header("Authorization", "Bearer token123")
      .retrieve()
      .bodyToMono(String.class)
      .block();

常见请求头示例

Authorization: Bearer xxx
Content-Type: application/json
Accept: application/json
User-Agent: MyApp/1.0

如果你告诉我：

• ✅ Java 版本
• ✅ 用的框架（Spring / Android / 原生）
• ✅ GET 还是 POST

我可以直接给你最合适的完整代码。