import java.util.ArrayList;
import java.util.List;
 
public class ProxyIPPool {
    private List<String> proxyIPs;
 
    public ProxyIPPool() {
        this.proxyIPs = new ArrayList<>();
    }
 
    public synchronized void addProxyIP(String proxyIP) {
        proxyIPs.add(proxyIP);
    }
 
    public synchronized String getProxyIP() {
        if (proxyIPs.isEmpty()) {
            return null;
        }
        String proxyIP = proxyIPs.remove(0);
        proxyIPs.add(proxyIP);
        return proxyIP;
    }
 
    public synchronized void removeProxyIP(String proxyIP) {
        proxyIPs.remove(proxyIP);
    }
 
    public synchronized int size() {
        return proxyIPs.size();
    }
}

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.InetSocketAddress;
import java.net.Proxy;
import java.net.URL;
 
public class ProxyIPForwarder {
    private ProxyIPPool proxyIPPool;
 
    public ProxyIPForwarder(ProxyIPPool proxyIPPool) {
        this.proxyIPPool = proxyIPPool;
    }
 
    public void forwardRequest(String url) throws IOException {
        String proxyIP = proxyIPPool.getProxyIP();
        if (proxyIP == null) {
            throw new RuntimeException("No available proxy IP.");
        }
 
        URL targetUrl = new URL(url);
        Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyIP, 80));
        HttpURLConnection connection = (HttpURLConnection) targetUrl.openConnection(proxy);
        connection.setRequestMethod("GET");
        // 设置其他请求头和参数
 
        // 发送请求
        int responseCode = connection.getResponseCode();
 
        // 根据响应码进行处理
 
        // 请求完成后将代理IP放回池中
        proxyIPPool.addProxyIP(proxyIP);
    }
}