推荐HttpClient工具类

依赖

<!-- Apache HttpClient 核心依赖 -->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version> <!-- 或更高版本 -->
</dependency>

<!-- SSL/TLS 支持 -->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient-cache</artifactId>
    <version>4.5.13</version>
</dependency>

<!-- 日志实现（按需选其一） -->
<!-- 方案1：Logback -->
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.2.11</version>
</dependency>

<!-- 方案2：Log4j2 -->
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.17.2</version>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-slf4j-impl</artifactId>
    <version>2.17.2</version>
</dependency>

关键依赖说明：

1. httpclient：提供核心HTTP客户端功能
2. httpclient-cache：包含SSL/TLS支持所需类（如SSLConnectionSocketFactory）
3. 日志依赖：必须添加日志实现才能看到连接池的DEBUG日志

验证依赖是否齐全的小技巧：

mvn dependency:tree | grep 'httpclient'
# 应该看到：
# org.apache.httpcomponents:httpclient:jar:4.5.13
# org.apache.httpcomponents:httpcore:jar:4.4.15
# org.apache.httpcomponents:httpclient-cache:jar:4.5.13

工具类

import org.apache.http.*;
import org.apache.http.client.config.*;
import org.apache.http.conn.ssl.*;
import org.apache.http.impl.client.*;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import javax.net.ssl.*;
import java.security.cert.X509Certificate;

public class HttpsDiagnosisClient {
    private static volatile CloseableHttpClient httpClient;
    private static final int MAX_TOTAL = 1000;
    private static final int MAX_PER_ROUTE = 200;
    private static final int CONN_REQUEST_TIMEOUT = 1000; // 连接池获取超时
    private static final int CONNECT_TIMEOUT = 250;       // 连接建立超时
    private static final int SOCKET_TIMEOUT = 1000;      // 数据传输超时

    // 双重检查锁单例模式
    public static CloseableHttpClient getInstance() {
        if (httpClient == null) {
            synchronized (HttpsDiagnosisClient.class) {
                if (httpClient == null) {
                    httpClient = createHttpsClient();
                }
            }
        }
        return httpClient;
    }

    private static CloseableHttpClient createHttpsClient() {
        try {
            // 1. 创建信任所有证书的SSL上下文（生产环境建议使用正式证书）
            SSLContext sslContext = SSLContexts.custom()
                    .loadTrustMaterial(null, (X509Certificate[] chain, String authType) -> true)
                    .build();

            // 2. 配置连接池（关键！开启诊断）
            PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager();
            connManager.setMaxTotal(MAX_TOTAL);
            connManager.setDefaultMaxPerRoute(MAX_PER_ROUTE);
            
            // 3. 创建带诊断的HttpClient
            return HttpClients.custom()
                    .setConnectionManager(connManager)
                    .setSSLSocketFactory(new SSLConnectionSocketFactory(sslContext,
                            new String[]{"TLSv1.2", "TLSv1.3"}, // 指定TLS版本
                            null,
                            NoopHostnameVerifier.INSTANCE))
                    .setDefaultRequestConfig(RequestConfig.custom()
                            .setConnectionRequestTimeout(CONN_REQUEST_TIMEOUT)
                            .setConnectTimeout(CONNECT_TIMEOUT)
                            .setSocketTimeout(SOCKET_TIMEOUT)
                            .build())
                    // 添加耗时拦截器
                    .addInterceptorLast(new TimingInterceptor())
                    .build();
        } catch (Exception e) {
            throw new RuntimeException("创建HTTPS客户端失败", e);
        }
    }

    // 耗时统计拦截器
    private static class TimingInterceptor implements HttpResponseInterceptor {
        @Override
        public void process(HttpResponse response, HttpContext context) {
            HttpClientContext clientContext = HttpClientContext.adapt(context);
            TimingInfo timing = clientContext.getAttribute("timing", TimingInfo.class);
            
            if (timing != null) {
                long totalTime = System.currentTimeMillis() - timing.startTime;
                System.out.printf("""
                    [HTTP Timing Diagnostics]
                    |-- 连接池等待: %dms
                    |-- DNS解析: %dms
                    |-- TCP握手: %dms
                    |-- SSL握手: %dms
                    |-- 请求发送: %dms
                    |-- 响应接收: %dms
                    |-- 总耗时: %dms
                    """, 
                    timing.connectionPoolTime,
                    timing.dnsTime,
                    timing.tcpHandshakeTime,
                    timing.sslHandshakeTime,
                    timing.requestSendTime,
                    timing.responseReceiveTime,
                    totalTime);
            }
        }
    }

    // 计时信息载体
    private static class TimingInfo {
        long startTime;
        long connectionPoolTime;
        long dnsTime;
        long tcpHandshakeTime;
        long sslHandshakeTime;
        long requestSendTime;
        long responseReceiveTime;
    }
}

需要配合以下日志配置（logback.xml示例）：

<!-- 连接池状态监控 -->
<logger name="org.apache.http.impl.conn.PoolingHttpClientConnectionManager" level="DEBUG"/>
  
<!-- 各阶段耗时日志 -->
<logger name="org.apache.http.impl.execchain" level="TRACE"/>
<logger name="org.apache.http.client.protocol" level="DEBUG"/>

工具类特点：

1. HTTPS优化：
   • 指定TLSv1.2+协议