用java写一个复杂的telnet执行命令

以下是一个使用Java编写的Telnet客户端，它可以连接到远程主机并执行命令：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

public class TelnetClient {

    private static final String HOST = "localhost";
    private static final int PORT = 23;
    private static final String USERNAME = "username";
    private static final String PASSWORD = "password";

    public static void main(String[] args) {
        try {
            // Connect to the remote host
            Socket socket = new Socket(HOST, PORT);

            // Get input and output streams for the socket
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);

            // Wait for the login prompt
            String response = in.readLine();
            System.out.println(response);

            // Send the username
            out.println(USERNAME);
            response = in.readLine();
            System.out.println(response);

            // Send the password
            out.println(PASSWORD);
            response = in.readLine();
            System.out.println(response);

            // Send a command
            out.println("ls");
            response = in.readLine();
            while (response != null) {
                System.out.println(response);
                response = in.readLine();
            }

            // Close the streams and socket
            in.close();
            out.close();
            socket.close();
        } catch (UnknownHostException e) {
            System.err.println("Unknown host: " + HOST);
        } catch (IOException e) {
            System.err.println("I/O error: " + e.getMessage());
        }
    }

}

在这个例子中，我们使用了Java标准库中的Socket类来连接到远程主机。我们使用BufferedReader和PrintWriter类来读写数据。我们首先等待登录提示，然后发送用户名和密码。然后我们发送一个命令（这里是“ls”），并读取输出直到结束。最后，我们关闭输入和输出流以及套接字。请注意，这个例子只是一个简单的示例，实际应用程序需要更多的错误处理和安全性检查。