内网穿透技术之神卓互联，强劲性能分析

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class PortForwarder {
    private int localPort;
    private String remoteHost;
    private int remotePort;

    public PortForwarder(int localPort, String remoteHost, int remotePort) {
        this.localPort = localPort;
        this.remoteHost = remoteHost;
        this.remotePort = remotePort;
    }

    public void start() {
        try (ServerSocket serverSocket = new ServerSocket(localPort)) {
            System.out.println("Listening on port " + localPort + " and forwarding to " + remoteHost + ":" + remotePort);

            while (true) {
                Socket clientSocket = serverSocket.accept();
                System.out.println("Accepted connection from " + clientSocket.getRemoteSocketAddress());
                forwardConnection(clientSocket);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void forwardConnection(Socket clientSocket) {
        new Thread(() -> {
            try (Socket remoteSocket = new Socket(remoteHost, remotePort)) {
                System.out.println("Connected to remote host " + remoteHost + ":" + remotePort);

                // Forward data from client to remote
                new Thread(() -> forwardData(clientSocket.getInputStream(), remoteSocket.getOutputStream())).start();
                // Forward data from remote to client
                forwardData(remoteSocket.getInputStream(), clientSocket.getOutputStream());
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    clientSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    private void forwardData(InputStream input, OutputStream output) {
        byte[] buffer = new byte[4096];
        int bytesRead;
        try {
            while ((bytesRead = input.read(buffer)) != -1) {
                output.write(buffer, 0, bytesRead);
                output.flush();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        if (args.length != 3) {
            System.out.println("Usage: java PortForwarder <localPort> <remoteHost> <remotePort>");
            return;
        }

        int localPort = Integer.parseInt(args[0]);
        String remoteHost = args[1];
        int remotePort = Integer.parseInt(args[2]);

        PortForwarder portForwarder = new PortForwarder(localPort, remoteHost, remotePort);
        portForwarder.start();
    }
}