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java如何请求长链接

2026-03-18 18:08:33Java

使用 Java 请求长链接（HTTP Keep-Alive）

在 Java 中实现长链接（HTTP Keep-Alive）可以通过以下方法完成，主要利用 HttpURLConnection 或第三方库如 Apache HttpClient。

使用 HttpURLConnection 实现

默认情况下，HTTP/1.1 支持 Keep-Alive，但需要正确设置连接参数。

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class KeepAliveExample {
    public static void main(String[] args) throws Exception {
        URL url = new URL("http://example.com");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        // 启用 Keep-Alive
        connection.setRequestProperty("Connection", "Keep-Alive");

        // 设置超时时间（可选）
        connection.setConnectTimeout(5000);
        connection.setReadTimeout(5000);

        // 发送请求
        int responseCode = connection.getResponseCode();
        System.out.println("Response Code: " + responseCode);

        // 读取响应
        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.toString());
        }

        // 不关闭连接以便复用
        // connection.disconnect();
    }
}

使用 Apache HttpClient 实现

Apache HttpClient 提供了更高级的 Keep-Alive 支持。

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class HttpClientKeepAlive {
    public static void main(String[] args) throws Exception {
        try (CloseableHttpClient httpClient = HttpClients.createDefault()) {
            HttpGet request = new HttpGet("http://example.com");

            // 发送请求
            HttpResponse response = httpClient.execute(request);
            System.out.println("Status Code: " + response.getStatusLine().getStatusCode());

            // 读取响应
            String result = EntityUtils.toString(response.getEntity());
            System.out.println(result);
        }
    }
}

配置连接池（高级）

对于高频请求，可以使用连接池优化性能。

java如何请求长链接

import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class ConnectionPoolExample {
    public static void main(String[] args) {
        PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
        cm.setMaxTotal(100); // 最大连接数
        cm.setDefaultMaxPerRoute(20); // 每个路由的最大连接数

        try (CloseableHttpClient httpClient = HttpClients.custom()
                .setConnectionManager(cm)
                .build()) {
            // 使用 httpClient 发送请求
        }
    }
}