使用JSch在远程SSH会话上运行telnet命令

Z时代
2024-01-10
分类：问答

我正在telnetSSH

shell会话上运行命令，为了获得该命令，我在官方示例后面使用了JSch 。

我也在 *

这是

package Utility;
import com.jcraft.jsch.Channel;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
public class JavaTelnet {
    public static void main(String[] arg) {
        try {
            System.out.println(telnetConnection(USER_ID,PASSWORD,REMOTE_HOST));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static String telnetConnection(String user, String password, String host) throws JSchException, Exception {
      JSch jsch=new JSch();
      Session session=jsch.getSession(user, host, 22);
      session.setPassword(password);
      // It must not be recommended, but if you want to skip host-key check,
       session.setConfig("StrictHostKeyChecking", "no");
      session.connect();
      //session.connect(30000);   // making a connection with timeout.
      Channel channel=session.openChannel("shell");
      channel.connect();
      DataInputStream dataIn = new DataInputStream(channel.getInputStream());
      BufferedReader reader = new BufferedReader(new InputStreamReader(dataIn));
      DataOutputStream dataOut = new DataOutputStream(channel.getOutputStream());
      dataOut.writeBytes("telnet localhost 4242\r\n");
/*
* telnet COMMANDS here
*/
      dataOut.writeBytes("exit\r\n");
       dataOut.writeBytes("logout\r\n");
       dataOut.flush();
      String line = reader.readLine();
      String result = line +"\n";
      while ((line= reader.readLine())!=null){
          result += line +"\n";
      }
      dataIn.close();
      dataOut.close();
      System.out.println("disconnecting....");
      channel.disconnect();
      session.disconnect();
      return "done";
  }
}

看起来不错，但奇怪的是。如果我运行它，程序将无法执行。我认为它锁定 了while循环，

但是我不明白为什么。没有while循环，代码将到达终点，但是不执行任何shell命令。

作为IDE

您能帮我发现问题吗？

回答：

我知道了。

__在while循环中， line 永远不会为 null 。

为何在调试中起作用仍是一个谜。

我正在发布。我希望它对每个想做类似事情的人都有帮助。

package Utility;
import com.jcraft.jsch.Channel;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
public class JavaTelnet {
    public static void main(String[] arg) {
        try {
            System.out.println(telnetConnection(YOUR_COMMAND,YOUR_USER,YOUR_PASS,YOUR_HOST));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static String telnetConnection(String command, String user, String password, String host) throws JSchException, Exception {
      JSch jsch=new JSch();
      Session session=jsch.getSession(user, host, 22);
      session.setPassword(password);
      // It must not be recommended, but if you want to skip host-key check,
       session.setConfig("StrictHostKeyChecking", "no");
      session.connect(3000);
      //session.connect(30000);   // making a connection with timeout.
      Channel channel=session.openChannel("shell");
      channel.connect(3000);
      DataInputStream dataIn = new DataInputStream(channel.getInputStream());
      BufferedReader reader = new BufferedReader(new InputStreamReader(dataIn));
      DataOutputStream dataOut = new DataOutputStream(channel.getOutputStream());
      System.out.println("Starting telnet connection...");
      dataOut.writeBytes("telnet localhost 4242\r\n");
//      dataOut.writeBytes("enable\r\n");
      dataOut.writeBytes(command+"\r\n");
      dataOut.writeBytes("exit\r\n"); //exit from telnet
       dataOut.writeBytes("exit\r\n"); //exit from shell
       dataOut.flush();
      String line = reader.readLine();
      String result = line +"\n";
        while (!(line= reader.readLine()).equals("Connection closed by foreign host")){
          result += line +"\n";
      }
      dataIn.close();
      dataOut.close();
      channel.disconnect();
      session.disconnect();
      return result;
  }
}