Java端为Apache HttpClient接入HTTPDNS-移动研发平台-阿里云

本文档介绍在 Java 应用中使用 Apache HttpClient 接入 HTTPDNS 的方案。

1. 背景说明

Apache HttpClient 是 Java 生态中广泛使用的 HTTP 网络库，支持 4.x 和 5.x 两个主要版本。通过实现 DnsResolver 接口，可以将 HTTPDNS 集成到 HttpClient 中。

2. 实现自定义 DnsResolver

HttpClient 5.x

import org.apache.hc.client5.http.DnsResolver;
import com.alibaba.sdk.java.httpdns.HttpDnsClient;
import com.alibaba.sdk.java.httpdns.HTTPDNSResult;
import com.alibaba.sdk.java.httpdns.RequestIpType;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;

public class HttpDnsResolver implements DnsResolver {
    
    private final HttpDnsClient httpDnsClient;
    
    public HttpDnsResolver(HttpDnsClient httpDnsClient) {
        this.httpDnsClient = httpDnsClient;
    }

    @Override
    public String resolveCanonicalHostname(String host) {
        return host;
    }

    @Override
    public InetAddress[] resolve(String host) throws UnknownHostException {
        HTTPDNSResult result = httpDnsClient.getHttpDnsResultForHostSyncNonBlocking(host, RequestIpType.both);

        List<InetAddress> addresses = new ArrayList<>();
        try {
            if (result != null && result.getIps() != null) {
                for (String ip : result.getIps()) {
                    addresses.add(InetAddress.getByName(ip));
                }
            }
            if (result != null && result.getIpv6s() != null) {
                for (String ip : result.getIpv6s()) {
                    addresses.add(InetAddress.getByName(ip));
                }
            }
        } catch (UnknownHostException e) {
            // 忽略单个 IP 解析失败
        }
        
        if (!addresses.isEmpty()) {
            return addresses.toArray(new InetAddress[0]);
        }
        
        // 降级到系统 DNS
        return InetAddress.getAllByName(host);
    }
}

HttpClient 4.x

import org.apache.http.conn.DnsResolver;
import com.alibaba.sdk.java.httpdns.HttpDnsClient;
import com.alibaba.sdk.java.httpdns.HTTPDNSResult;
import com.alibaba.sdk.java.httpdns.RequestIpType;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;

public class HttpDnsResolver4 implements DnsResolver {
    
    private final HttpDnsClient httpDnsClient;
    
    public HttpDnsResolver4(HttpDnsClient httpDnsClient) {
        this.httpDnsClient = httpDnsClient;
    }

    @Override
    public InetAddress[] resolve(String host) throws UnknownHostException {
        HTTPDNSResult result = httpDnsClient.getHttpDnsResultForHostSyncNonBlocking(host, RequestIpType.both);

        List<InetAddress> addresses = new ArrayList<>();
        try {
            if (result != null && result.getIps() != null) {
                for (String ip : result.getIps()) {
                    addresses.add(InetAddress.getByName(ip));
                }
            }
            if (result != null && result.getIpv6s() != null) {
                for (String ip : result.getIpv6s()) {
                    addresses.add(InetAddress.getByName(ip));
                }
            }
        } catch (UnknownHostException e) {
            // 忽略单个 IP 解析失败
        }
        
        if (!addresses.isEmpty()) {
            return addresses.toArray(new InetAddress[0]);
        }
        
        // 降级到系统 DNS
        return InetAddress.getAllByName(host);
    }
}

说明

4.x 和 5.x 的 DnsResolver 来自不同的包，5.x 需额外实现 resolveCanonicalHostname() 方法。

3. 配置 HttpClient

HttpClient 5.x

import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManagerBuilder;
import org.apache.hc.client5.http.io.HttpClientConnectionManager;

HttpDnsClient httpDnsClient = HttpDnsClient.getClient(accountId);

HttpClientConnectionManager connectionManager = PoolingHttpClientConnectionManagerBuilder.create()
    .setDnsResolver(new HttpDnsResolver(httpDnsClient))
    .build();

CloseableHttpClient httpClient = HttpClients.custom()
    .setConnectionManager(connectionManager)
    .build();

HttpClient 4.x

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

HttpDnsClient httpDnsClient = HttpDnsClient.getClient(accountId);

CloseableHttpClient httpClient = HttpClients.custom()
    .setDnsResolver(new HttpDnsResolver4(httpDnsClient))
    .build();

4. 总结

Apache HttpClient + HTTPDNS 的主要优势：

实现简单：只需实现 DnsResolver 接口即可接入
通用性强：在 HTTPS、SNI 以及设置 Cookie 等场景均适用，无需额外处理证书校验、域名检查等环节
版本兼容：同时支持 HttpClient 4.x 和 5.x