gateway的底层实现java

Gateway的底层实现可以使用Java编写，以下是一个简单的实现示例：

import java.io.*;
import java.net.*;

public class Gateway {
    private int port;
    private String targetHost;
    private int targetPort;

    public Gateway(int port, String targetHost, int targetPort) {
        this.port = port;
        this.targetHost = targetHost;
        this.targetPort = targetPort;
    }

    public void start() throws IOException {
        ServerSocket serverSocket = new ServerSocket(port);
        while (true) {
            Socket clientSocket = serverSocket.accept();
            Thread thread = new Thread(() -> {
                try {
                    Socket targetSocket = new Socket(targetHost, targetPort);
                    InputStream clientIn = clientSocket.getInputStream();
                    OutputStream clientOut = clientSocket.getOutputStream();
                    InputStream targetIn = targetSocket.getInputStream();
                    OutputStream targetOut = targetSocket.getOutputStream();
                    byte[] buffer = new byte[1024];
                    int len;
                    while ((len = clientIn.read(buffer)) != -1) {
                        targetOut.write(buffer, 0, len);
                        targetOut.flush();
                    }
                    while ((len = targetIn.read(buffer)) != -1) {
                        clientOut.write(buffer, 0, len);
                        clientOut.flush();
                    }
                    clientSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            });
            thread.start();
        }
    }

    public static void main(String[] args) throws IOException {
        Gateway gateway = new Gateway(8080, "www.example.com", 80);
        gateway.start();
    }
}

该实现使用了Java的Socket和ServerSocket类，监听指定端口的请求，并将请求转发到目标主机和端口。在请求转发时使用了多线程，以避免阻塞其他请求。