java程序发送异步http请求

方法一：使用 Java 11+ 内置的 HttpClient（推荐）

Java 11 引入了新的 HttpClient 支持异步请求，无需第三方依赖。

import java.net.URI;
import java.net.http.*;
import java.util.concurrent.CompletableFuture;

public class AsyncHttpExample {
    public static void main(String[] args) {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create("https://api.example.com/data"))
                .build();

        CompletableFuture<HttpResponse<String>> future = 
            client.sendAsync(request, HttpResponse.BodyHandlers.ofString());

        future.thenApply(HttpResponse::body)
              .thenAccept(body -> System.out.println("响应内容: " + body))
              .exceptionally(ex -> {
                  System.err.println("请求失败: " + ex.getMessage());
                  return null;
              });

        // 防止主线程提前退出（仅示例，实际应用中不需要）
        future.join();
    }
}

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方法二：使用 OkHttp 异步请求

OkHttp 是一个流行的第三方HTTP客户端库，支持异步回调。

1. 添加依赖（Maven）：

   <dependency>
       <groupId>com.squareup.okhttp3groupId>
       <artifactId>okhttpartifactId>
       <version>4.12.0version>
   dependency>
   

2. 代码示例：

import okhttp3.*;
import java.io.IOException;

public class OkHttpAsyncExample {
    public static void main(String[] args) {
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url("https://api.example.com/data")
                .build();

        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onResponse(Call call, Response response) throws IOException {
                if (response.isSuccessful()) {
                    String body = response.body().string();
                    System.out.println("响应内容: " + body);
                } else {
                    System.err.println("请求失败: " + response.code());
                }
            }

            @Override
            public void onFailure(Call call, IOException e) {
                System.err.println("请求失败: " + e.getMessage());
            }
        });
    }
}

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方法三：使用 Apache HttpClient 异步模块

Apache HttpClient 提供了异步支持，但配置稍复杂。

1. 添加依赖（Maven）：

   <dependency>
       <groupId>org.apache.httpcomponentsgroupId>
       <artifactId>httpasyncclientartifactId>
       <version>4.1.5version>
   dependency>
   

2. 代码示例：

import org.apache.http.*;
import org.apache.http.client.methods.*;
import org.apache.http.impl.nio.client.*;
import java.util.concurrent.Future;

public class ApacheAsyncExample {
    public static void main(String[] args) throws Exception {
        CloseableHttpAsyncClient client = HttpAsyncClients.createDefault();
        client.start();

        HttpGet request = new HttpGet("https://api.example.com/data");
        Future<HttpResponse> future = client.execute(request, new FutureCallback<HttpResponse>() {
            @Override
            public void completed(HttpResponse response) {
                System.out.println("响应状态: " + response.getStatusLine());
                // 处理响应内容
            }

            @Override
            public void failed(Exception ex) {
                System.err.println("请求失败: " + ex.getMessage());
            }

            @Override
            public void cancelled() {
                System.err.println("请求取消");
            }
        });

        // 如果需要等待结果
        future.get();
        client.close();
    }
}

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关键点总结

1. Java 11+ HttpClient：官方推荐，无需额外依赖，语法简洁。
2. OkHttp：第三方库中性能优秀，API 设计友好。
3. Apache HttpClient：适合需要更底层控制的老项目。