常用的http请求方式

在 Java 中，常用的发起 HTTP 请求的方式或工具类有以下几种：

---

1. 原生 Java 方式

(1) HttpURLConnection

• 特点：Java 标准库提供的 HTTP 客户端，无需额外依赖。

• 示例：

  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 {
          URL url = new URL("https://jsonplaceholder.typicode.com/posts/1");
          HttpURLConnection connection = (HttpURLConnection) url.openConnection();
          connection.setRequestMethod("GET");
  
          int responseCode = connection.getResponseCode();
          System.out.println("Response Code: " + responseCode);
  
          BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
          String inputLine;
          StringBuilder response = new StringBuilder();
  
          while ((inputLine = in.readLine()) != null) {
              response.append(inputLine);
          }
          in.close();
  
          System.out.println("Response: " + response.toString());
      }
  }
  

---

2. 第三方库

(1) OkHttp

• 特点：Square 开源的 HTTP 客户端，性能优异，API 简洁。

• 依赖：

  <dependency>
      <groupId>com.squareup.okhttp3</groupId>
      <artifactId>okhttp</artifactId>
      <version>4.10.0</version>
  </dependency>
  

• 示例：

  import okhttp3.OkHttpClient;
  import okhttp3.Request;
  import okhttp3.Response;
  
  public class OkHttpExample {
      public static void main(String[] args) throws Exception {
          OkHttpClient client = new OkHttpClient();
  
          Request request = new Request.Builder()
                  .url("https://jsonplaceholder.typicode.com/posts/1")
                  .build();
  
          try (Response response = client.newCall(request).execute()) {
              System.out.println("Response Code: " + response.code());
              System.out.println("Response Body: " + response.body().string());
          }
      }
  }
  

(2) Apache HttpClient

• 特点：Apache 提供的 HTTP 客户端，功能强大，支持高级特性。

• 依赖：

  <dependency>
      <groupId>org.apache.httpcomponents.client5</groupId>
      <artifactId>httpclient5</artifactId>
      <version>5.1.3</version>
  </dependency>
  

• 示例：

  import org.apache.hc.client5.http.classic.methods.HttpGet;
  import org.apache.hc.client5.http.classic.methods.CloseableHttpResponse;
  import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  import org.apache.hc.client5.http.impl.classic.HttpClients;
  import org.apache.hc.core5.http.io.entity.EntityUtils;
  
  public class HttpClientExample {
      public static void main(String[] args) throws Exception {
          try (CloseableHttpClient client = HttpClients.createDefault()) {
              HttpGet request = new HttpGet("https://jsonplaceholder.typicode.com/posts/1");
  
              try (CloseableHttpResponse response = client.execute(request)) {
                  System.out.println("Response Code: " + response.getCode());
                  System.out.println("Response Body: " + EntityUtils.toString(response.getEntity()));
              }
          }
      }
  }
  

(3) Spring RestTemplate

• 特点：Spring 提供的 HTTP 客户端，集成 Spring 生态，适合 Spring 项目。

• 依赖：

  <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  

• 示例：

  import org.springframework.web.client.RestTemplate;
  
  public class RestTemplateExample {
      public static void main(String[] args) {
          RestTemplate restTemplate = new RestTemplate();
          String url = "https://jsonplaceholder.typicode.com/posts/1";
  
          String response = restTemplate.getForObject(url, String.class);
          System.out.println("Response: " + response);
      }
  }
  

(4) Spring WebClient

• 特点：Spring 5 引入的响应式 HTTP 客户端，支持异步和非阻塞。

• 依赖：

  <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-webflux</artifactId>
  </dependency>
  

• 示例：

  import org.springframework.web.reactive.function.client.WebClient;
  import reactor.core.publisher.Mono;
  
  public class WebClientExample {
      public static void main(String[] args) {
          WebClient client = WebClient.create();
  
          Mono<String> response = client.get()
                  .uri("https://jsonplaceholder.typicode.com/posts/1")
                  .retrieve()
                  .bodyToMono(String.class);
  
          System.out.println("Response: " + response.block());
      }
  }
  

---

3. 工具类封装

(1) 基于 OkHttp 的工具类

import okhttp3.*;

import java.io.IOException;

public class OkHttpUtils {
    private static final OkHttpClient client = new OkHttpClient();

    public static String get(String url) throws IOException {
        Request request = new Request.Builder()
                .url(url)
                .build();

        try (Response response = client.newCall(request).execute()) {
            if (!response.isSuccessful()) {
                throw new IOException("Unexpected code: " + response.code());
            }
            return response.body().string();
        }
    }

    public static String post(String url, String json) throws IOException {
        RequestBody body = RequestBody.create(json, MediaType.parse("application/json"));
        Request request = new Request.Builder()
                .url(url)
                .post(body)
                .build();

        try (Response response = client.newCall(request).execute()) {
            if (!response.isSuccessful()) {
                throw new IOException("Unexpected code: " + response.code());
            }
            return response.body().string();
        }
    }
}

(2) 基于 RestTemplate 的工具类

import org.springframework.web.client.RestTemplate;

public class RestTemplateUtils {
    private static final RestTemplate restTemplate = new RestTemplate();

    public static String get(String url) {
        return restTemplate.getForObject(url, String.class);
    }

    public static String post(String url, Object request) {
        return restTemplate.postForObject(url, request, String.class);
    }
}

---

4. 对比与选择

工具/库	优点	缺点	适用场景
HttpURLConnection	无需额外依赖，适合简单场景	API 繁琐，功能有限	简单 HTTP 请求
OkHttp	性能优异，API 简洁	需要额外依赖	高性能 HTTP 请求
Apache HttpClient	功能强大，支持高级特性	API 复杂，依赖较多	复杂 HTTP 请求
RestTemplate	集成 Spring 生态，API 简单	同步阻塞，不支持响应式编程	Spring 项目中的 HTTP 请求
WebClient	支持响应式编程，异步非阻塞	需要学习响应式编程	Spring 5+ 项目中的 HTTP 请求

---

总结

• 推荐工具：

  • 如果需要高性能和简洁 API，选择 OkHttp。
  • 如果是 Spring 项目，选择 RestTemplate 或 WebClient。
  • 如果需要高级功能，选择 Apache HttpClient。

• 工具类封装：根据项目需求封装工具类，提高代码复用性。