Java 调用 HTTP 接口的 7 种方式示例代码(全网最全指南)
作者:愤怒的代码
在开发过程中,调用 HTTP 接口是最常见的需求之一,本文将详细介绍 Java 中 7 种主流的调用 HTTP 接口的方式,包括每种工具的优缺点和完整代码实现,感兴趣的朋友一起看看吧
Java 调用 HTTP 接口的 7 种方式:全网最全指南
在开发过程中,调用 HTTP 接口是最常见的需求之一。本文将详细介绍 Java 中 7 种主流的调用 HTTP 接口的方式,包括每种工具的优缺点和完整代码实现。
1. 使用 RestTemplate
RestTemplate
是 Spring 提供的同步 HTTP 客户端,适用于传统项目。尽管从 Spring 5 开始被标记为过时,它仍然是许多开发者的首选。
示例代码
import org.springframework.web.client.RestTemplate; import org.springframework.http.ResponseEntity; import org.springframework.http.HttpHeaders; import org.springframework.http.HttpEntity; import org.springframework.http.HttpMethod; import org.springframework.http.MediaType; public class RestTemplateExample { public static void main(String[] args) { // 接口地址 String url = "https://your-api-url.com/target-method"; // 设置请求头 HttpHeaders headers = new HttpHeaders(); headers.setContentType(MediaType.APPLICATION_JSON); headers.add("appId", "yourAppId"); headers.add("timestamp", "yourTimestamp"); headers.add("random", "yourRandom"); headers.add("msgDigest", "yourMsgDigest"); // 设置请求体 String requestBody = """ { "fileName": "yourFileName", "fileSize": yourFileSize, "dataType": "yourDataType", "certificate": "yourCertificate", "deposit": "yourDeposit", "fileHash": "yourFileHash", "userId": "yourUserId", "appId": "yourAppId" } """; // 构造请求 RestTemplate restTemplate = new RestTemplate(); HttpEntity<String> entity = new HttpEntity<>(requestBody, headers); // 发送请求 ResponseEntity<String> response = restTemplate.exchange(url, HttpMethod.POST, entity, String.class); // 输出响应结果 System.out.println("Response: " + response.getBody()); } }
优缺点
- 优点: 简单易用,适合快速开发。
- 缺点: 已过时,不推荐用于新项目。
2. 使用 WebClient
WebClient
是 Spring 5 引入的现代化 HTTP 客户端,支持同步和异步调用。
示例代码
import org.springframework.web.reactive.function.client.WebClient; import org.springframework.http.HttpHeaders; import org.springframework.http.MediaType; public class WebClientExample { public static void main(String[] args) { // 创建 WebClient WebClient webClient = WebClient.builder() .baseUrl("https://your-api-url.com") .defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE) .defaultHeader("appId", "yourAppId") .defaultHeader("timestamp", "yourTimestamp") .defaultHeader("random", "yourRandom") .defaultHeader("msgDigest", "yourMsgDigest") .build(); // 设置请求体 String requestBody = """ { "fileName": "yourFileName", "fileSize": yourFileSize, "dataType": "yourDataType", "certificate": "yourCertificate", "deposit": "yourDeposit", "fileHash": "yourFileHash", "userId": "yourUserId", "appId": "yourAppId" } """; // 发送请求 String response = webClient.post() .uri("/target-method") .bodyValue(requestBody) .retrieve() .bodyToMono(String.class) .block(); // 同步调用 // 输出响应结果 System.out.println("Response: " + response); } }
优缺点
- 优点: 支持响应式编程,功能强大。
- 缺点: API 较复杂,学习曲线较高。
3. 使用 OkHttp
OkHttp
是一个轻量级、高性能的 HTTP 客户端,支持同步和异步调用。
示例代码
import okhttp3.*; public class OkHttpExample { public static void main(String[] args) throws Exception { // 创建 OkHttp 客户端 OkHttpClient client = new OkHttpClient(); // 设置请求体 String requestBody = """ { "fileName": "yourFileName", "fileSize": yourFileSize, "dataType": "yourDataType", "certificate": "yourCertificate", "deposit": "yourDeposit", "fileHash": "yourFileHash", "userId": "yourUserId", "appId": "yourAppId" } """; // 构造请求 Request request = new Request.Builder() .url("https://your-api-url.com/target-method") .post(RequestBody.create(requestBody, MediaType.parse("application/json"))) .addHeader("appId", "yourAppId") .addHeader("timestamp", "yourTimestamp") .addHeader("random", "yourRandom") .addHeader("msgDigest", "yourMsgDigest") .build(); // 发送请求 try (Response response = client.newCall(request).execute()) { if (response.isSuccessful()) { System.out.println("Response: " + response.body().string()); } else { System.err.println("Request failed: " + response.code()); } } } }
优缺点
- 优点: 高性能,支持异步调用。
- 缺点: 需要手动管理连接,代码量较多。
4. 使用 Apache HttpClient
Apache HttpClient
是一个功能强大且稳定的 HTTP 客户端,适合需要复杂功能(如代理、认证、多线程支持)的场景。
示例代码
import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; public class HttpClientExample { public static void main(String[] args) throws Exception { // 创建 HttpClient CloseableHttpClient httpClient = HttpClients.createDefault(); // 设置请求地址 String url = "https://your-api-url.com/target-method"; HttpPost httpPost = new HttpPost(url); // 设置请求头 httpPost.setHeader("Content-Type", "application/json"); httpPost.setHeader("appId", "yourAppId"); httpPost.setHeader("timestamp", "yourTimestamp"); httpPost.setHeader("random", "yourRandom"); httpPost.setHeader("msgDigest", "yourMsgDigest"); // 设置请求体 String requestBody = """ { "fileName": "yourFileName", "fileSize": yourFileSize, "dataType": "yourDataType", "certificate": "yourCertificate", "deposit": "yourDeposit", "fileHash": "yourFileHash", "userId": "yourUserId", "appId": "yourAppId" } """; httpPost.setEntity(new StringEntity(requestBody)); // 发送请求 try (CloseableHttpResponse response = httpClient.execute(httpPost)) { String responseString = EntityUtils.toString(response.getEntity()); System.out.println("Response: " + responseString); } } }
优缺点
- 优点: 功能强大,支持多线程、代理、连接池等。
- 缺点: API 较为复杂,代码量较多。
5. 使用 Retrofit
Retrofit
是基于 OkHttp 的类型安全 HTTP 客户端,适合优雅地调用 REST API。
示例代码
定义接口
import retrofit2.Call; import retrofit2.http.Body; import retrofit2.http.Headers; import retrofit2.http.POST; public interface ApiService { @POST("/target-method") @Headers({ "Content-Type: application/json", "appId: yourAppId", "timestamp: yourTimestamp", "random: yourRandom", "msgDigest: yourMsgDigest" }) Call<String> createCz(@Body String requestBody); }
调用服务
import retrofit2.Retrofit; import retrofit2.converter.gson.GsonConverterFactory; import retrofit2.Call; import retrofit2.Response; public class RetrofitExample { public static void main(String[] args) throws Exception { // 创建 Retrofit 实例 Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://your-api-url.com") .addConverterFactory(GsonConverterFactory.create()) .build(); // 创建接口实例 ApiService apiService = retrofit.create(ApiService.class); // 构造请求体 String requestBody = """ { "fileName": "yourFileName", "fileSize": yourFileSize, "dataType": "yourDataType", "certificate": "yourCertificate", "deposit": "yourDeposit", "fileHash": "yourFileHash", "userId": "yourUserId", "appId": "yourAppId" } """; // 调用接口 Call<String> call = apiService.createCz(requestBody); Response<String> response = call.execute(); if (response.isSuccessful()) { System.out.println("Response: " + response.body()); } else { System.err.println("Request failed: " + response.code()); } } }
优缺点
- 优点: 注解式调用,简洁高效,自动处理 JSON。
- 缺点: 适合中小型项目,不适合复杂场景。
6. 使用 HttpURLConnection
HttpURLConnection
是 Java 自带的原生 HTTP 客户端,适合不想引入外部依赖的小型项目。
示例代码
import java.io.OutputStream; import java.io.BufferedReader; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.URL; public class HttpURLConnectionExample { public static void main(String[] args) throws Exception { // 设置请求地址 URL url = new URL("https://your-api-url.com/target-method"); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); // 设置请求方法和属性 connection.setRequestMethod("POST"); connection.setRequestProperty("Content-Type", "application/json"); connection.setRequestProperty("appId", "yourAppId"); connection.setRequestProperty("timestamp", "yourTimestamp"); connection.setRequestProperty("random", "yourRandom"); connection.setRequestProperty("msgDigest", "yourMsgDigest"); connection.setDoOutput(true); // 设置请求体 String requestBody = """ { "fileName": "yourFileName", "fileSize": yourFileSize, "dataType": "yourDataType", "certificate": "yourCertificate", "deposit": "yourDeposit", "fileHash": "yourFileHash", "userId": "yourUserId", "appId": "yourAppId" } """; try (OutputStream os = connection.getOutputStream()) { os.write(requestBody.getBytes()); os.flush(); } // 获取响应 int responseCode = connection.getResponseCode(); if (responseCode == 200) { try (BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()))) { String inputLine; StringBuilder response = new StringBuilder(); while ((inputLine = in.readLine()) != null) { response.append(inputLine); } System.out.println("Response: " + response.toString()); } } else { System.err.println("Request failed: " + responseCode); } } }
优缺点
- 优点: 无需额外依赖,适合简单场景。
- 缺点: API 使用繁琐,功能有限。
7. 使用 OpenFeign
OpenFeign
是 Spring Cloud 提供的声明式 HTTP 客户端,适用于微服务间的接口调用。
示例代码
Feign 客户端接口
import org.springframework.cloud.openfeign.FeignClient; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestHeader; @FeignClient(name = "czClient", url = "https://your-api-url.com") public interface CzClient { @PostMapping(value = "/target-method") String createCz( @RequestHeader("appId") String appId, @RequestHeader("timestamp") String timestamp, @RequestHeader("random") String random, @RequestHeader("msgDigest") String msgDigest, @RequestBody String requestBody ); }
服务调用逻辑
import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; @Service public class CzService { @Autowired private CzClient czClient; public void callCzApi() { String response = czClient.createCz( "yourAppId", "yourTimestamp", "yourRandom", "yourMsgDigest", """ { "fileName": "yourFileName", "fileSize": yourFileSize, "dataType": "yourDataType", "certificate": "yourCertificate", "deposit": "yourDeposit", "fileHash": "yourFileHash", "userId": "yourUserId", "appId": "yourAppId" } """ ); System.out.println("Response: " + response); } }
优缺点
- 优点: 声明式调用,集成 Spring 生态。
- 缺点: 依赖 Spring Cloud,不适用于非 Spring 项目。
总结
工具 | 适用场景 | 优点 | 缺点 |
---|---|---|---|
RestTemplate | 简单的同步调用 | 简单易用 | 已过时,不推荐新项目使用 |
WebClient | 高性能异步调用、响应式场景 | 支持异步与响应式调用 | API 较复杂 |
OkHttp | 性能要求高的小型项目 | 轻量高效,支持异步调用 | 需要手动管理,代码量较多 |
Apache HttpClient | 复杂场景,如代理、多线程、认证等 | 功能强大,稳定性高 | API 较复杂 |
Retrofit | 注解式调用 REST API | 简洁高效,自动处理 JSON | 适合中小型项目,不适合复杂场景 |
HttpURLConnection | 极简场景,无需额外依赖 | 内置支持,无需依赖外部库 | 使用复杂,功能有限 |
OpenFeign | 微服务间的接口调用 | 声明式调用,集成 Spring 生态 | 依赖 Spring Cloud,不适用于非 Spring 项目 |
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