当我再次单击该按钮时，为什么无法连接到JSch会话？

Question

我正在尝试制作一个使用JSch连接到树莓派的Android应用程序。我做了三个按钮。一个连接到会话，一个断开连接，另一个发送命令。第一次，连接按钮可以正常工作。但是，断开连接后，连接按钮不起作用。我在连接按钮的onClickListerner中放置了一条打印语句，当我再次单击该按钮时，该语句甚至无法打印。

我的OnCreateMethod

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_command_page);
    Intent intent = getIntent();
    name = intent.getStringExtra("name");
    if(name == null) {
        Log.d("NAME", "The name is null");
    }
    commandSnd = (Button) findViewById(R.id.sndCommand);
    text =  (TextView) findViewById(R.id.cmdOut);
    cmdInput = (EditText)findViewById(R.id.cmdInput);
    input = cmdInput.getText().toString();
    db = new DatabaseHelper(this);
    connect = (Button) findViewById(R.id.connect);
    disconnect = (Button) findViewById(R.id.disconnect);
    disconnect.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            new AsyncTask<Integer, Void, Void>() {
                protected  Void doInBackground(Integer... params) {

                    try {
                        disconnect(session);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    return null;
                }
            }.execute(1);
        }
    });;

    commandSnd = (Button) findViewById(R.id.sndCommand);
    text =  (TextView) findViewById(R.id.cmdOut);
    cmdInput = (EditText)findViewById(R.id.cmdInput);
    input = cmdInput.getText().toString();
    connect.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            System.out.print("Button has been Clicked");
            new AsyncTask<Integer, Void, Void>() {
                protected  Void doInBackground(Integer... params) {

                    try {
                        connect(name);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    return null;
                }
            }.execute(1);
        }
    });

    commandSnd.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            new AsyncTask<Integer, Void, Void>() {
                protected  Void doInBackground(Integer... params) {

                    try {
                        sendCommand(name, input);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    return null;
                }
            }.execute(1);
        }
    });

我的连接方法

    public Session connect(String n) throws JSchException {
    if (session == null) {
        current = new JSch();
        Properties config = new Properties();
        config.put("StrictHostKeyChecking", "no");

        String[] results = getDataStrings(n);
        String user = results[0];
        String host = results[1];
        session = current.getSession(user, host);
        session.setPassword(results[2]);
        session.setConfig(config);
        setVisible(commandSnd, View.VISIBLE);
        setVisible(disconnect, View.VISIBLE);
        setVisible(connect, View.INVISIBLE);
        session.connect();
        session.setServerAliveInterval(10000);
    } else if (session.isConnected()) {
        Toast.makeText(ButtonClickedActivity.this, "You already have a session connected", Toast.LENGTH_SHORT);
    }
    return session;

}

我的断开连接方法

  public void disconnect(Session a) {
    if (a.isConnected()) {
        setVisible(connect, View.VISIBLE);
        setVisible(disconnect, View.INVISIBLE);
        setVisible(commandSnd, View.INVISIBLE);
    }
    a.disconnect();

    setVisible(connect, View.VISIBLE);
    setVisible(disconnect, View.INVISIBLE);
    setVisible(commandSnd, View.INVISIBLE);

}

最后，我的commandSend方法

public String sendCommand(String n, String command) throws JSchException {
    String cmd = cmdInput.getText().toString();
    if(cmd.isEmpty()) {
        setText("Please insert a valid Command");
        return "Insert Valid Command";
    }
    System.out.println(cmd);
    Log.d("Command", cmd);
    String[] results = getDataStrings(n);
    String output;
    try {
        System.out.print("Channel Made");
        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ChannelExec channelSSH = (ChannelExec) session.openChannel("exec");
        channelSSH.setOutputStream(baos);
        channelSSH.setCommand(cmd);
        channelSSH.connect();
        try{ Thread.sleep(1000); } catch(Exception ee) {}
        output = new String(baos.toByteArray());
        System.out.println("CommandSent");
        System.out.println("byteCreated");
        System.out.println(output);
        setText(output);
        Log.d("Command Sent Check", output);
        channelSSH.disconnect();
    }
    catch(Exception e) {
        
        System.out.println("The connection failed");
        setText("The connection has failed");

        e.printStackTrace();
        return "Please Check your Selected pi's properties";
    }
    return output;

}

我怀疑这与我使用AsyncTask有关，但我可能会误会。