java Android异步任务永远不会结束

Question

我已经为Android编写了一个网络（JSch）异步任务。出于某种原因，AsyncTask永远不会结束，直到我再次调用buttonClick（）。这是我的密码：

public class MainActivity extends AppCompatActivity

{ @凌驾 创建时受保护的void（Bundle savedInstanceState） { 超级的onCreate（savedInstanceState）； setContentView（R.layout.activity_main）； }

    protected void buttonClick(View view)
    {
            System.out.println(" --------------------------------- ");
            System.out.println(" CONNECT BUTTON CLICKED!");
            System.out.println(" --------------------------------- ");
            new AsyncTask<Void, Void, Void>() {
                    @Override
                    protected Void doInBackground(Void... params)
                    {
                            connect();
                            System.out.println("Connect done");
                            return null;
                    }
                    protected Void onPostExecute()
                    {
                            System.out.println("PostExec done");
                            return null;
                    }
            }.execute();
            System.out.println("Done with ASyncTask");
            String text = output;
            TextView tv = (TextView)findViewById(R.id.ayy);
            tv.setText(text);
    }

    private int d;
    private String output;
    private void debug()
    {
            System.out.println("Debug" + d);
            d++;
    }

    private void connect()
    {
            d = 1;
            debug();
            JSch jsch = new JSch();
            String host = "[edited out]";
            String user = "[edited out]";
            String password = "[edited out for obvious reasons]";
            String command = "uname -a";
            int port = 2223;
            try {
                    debug();
                    Session session = jsch.getSession(user, host, port);
                    debug();
                    UserInfo ui = new MyUserInfo();
                    debug();
                    session.setUserInfo(ui);
                    debug();
                    session.connect();
                    debug();
                    Channel channel = session.openChannel("exec");
                    debug();
                    ((ChannelExec) channel).setCommand(command);
                    debug();
                    channel.setInputStream(null);
                    debug();
                    ((ChannelExec) channel).setErrStream(System.err);
                    debug();
                    InputStream in = channel.getInputStream();
                    debug();
                    channel.connect();
                    debug();
                    byte[] tmp = new byte[1024];
                    while(true) {
                            while(in.available() > 0) {
                                    int i = in.read(tmp, 0, 1024);
                                    if(i < 0) break;
                                    output = output + new String(tmp, 0, i);
                            }
                            if(channel.isClosed()) {
                                    if(in.available() > 0) continue;
                                    System.out.println("exit-status: " + channel.getExitStatus());
                                    break;
                            }
                            try {
                                    Thread.sleep(1000);
                            } catch(Exception ee) {

                            }
                    }
                    channel.disconnect();
                    session.disconnect();
            } catch(Exception e) {
                    System.err.println("Exception: " + e);
                    e.printStackTrace();
            }
    }
  }

  class MyUserInfo implements UserInfo, UIKeyboardInteractive
  {
    public String getPassword()
    {
            return passwd;
    }

    public boolean promptYesNo(String str)
    {
                    /*Object[] options = {"yes", "no"};
                    int foo = JOptionPane.showOptionDialog(null,
                            str,
                            "Warning",
                            JOptionPane.DEFAULT_OPTION,
                            JOptionPane.WARNING_MESSAGE,
                            null, options, options[0]);
                    return foo == 0; */
            return true;
    }

    String passwd;

    public String getPassphrase()
    {
            return null;
    }

    public boolean promptPassphrase(String message)
    {
            return true;
    }

    public boolean promptPassword(String message)
    {
            passwd = "[edited out]";
            return true;
    }

    public void showMessage(String message)
    {
            System.out.println("MSG: " + message);
    }

    /*
    final GridBagConstraints gbc =
            new GridBagConstraints(0, 0, 1, 1, 1, 1,
                    GridBagConstraints.NORTHWEST,
                    GridBagConstraints.NONE,
                    new Insets(0, 0, 0, 0), 0, 0);
    private Container panel;
    */
    public String[] promptKeyboardInteractive(String destination,
                                              String name,
                                              String instruction,
                                              String[] prompt,
                                              boolean[] echo)
    { System.out.println("promptKeyboardInteractive");/*
            panel = new JPanel();
            panel.setLayout(new GridBagLayout());

            gbc.weightx = 1.0;
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            gbc.gridx = 0;
            panel.add(new JLabel(instruction), gbc);
            gbc.gridy++;

            gbc.gridwidth = GridBagConstraints.RELATIVE;

            JTextField[] texts = new JTextField[prompt.length];
            for(int i = 0; i < prompt.length; i++) {
                    gbc.fill = GridBagConstraints.NONE;
                    gbc.gridx = 0;
                    gbc.weightx = 1;
                    panel.add(new JLabel(prompt[i]), gbc);

                    gbc.gridx = 1;
                    gbc.fill = GridBagConstraints.HORIZONTAL;
                    gbc.weighty = 1;
                    if(echo[i]) {
                            texts[i] = new JTextField(20);
                    } else {
                            texts[i] = new JPasswordField(20);
                    }
                    panel.add(texts[i], gbc);
                    gbc.gridy++;
            }

            if(JOptionPane.showConfirmDialog(null, panel,
                    destination + ": " + name,
                    JOptionPane.OK_CANCEL_OPTION,
                    JOptionPane.QUESTION_MESSAGE)
                    == JOptionPane.OK_OPTION) {
                    String[] response = new String[prompt.length];
                    for(int i = 0; i < prompt.length; i++) {
                            response[i] = texts[i].getText();
                    }
                    return response;
            } else {
                    return null;  // cancel
            }
    */
            return null;
      }
}

我完全知道代码是一团乱麻，但一旦我开始工作，我会把它清理干净

单击1个按钮后输出：

04-13 15:45:33.451 26826-26826/com.example.ryan.jschtest I/System.out:  --------------------------------- 
04-13 15:45:33.451 26826-26826/com.example.ryan.jschtest I/System.out:  CONNECT BUTTON CLICKED!
04-13 15:45:33.451 26826-26826/com.example.ryan.jschtest I/System.out:  --------------------------------- 
04-13 15:45:33.452 26826-26826/com.example.ryan.jschtest I/System.out: Done with Asynctask
04-13 15:45:33.452 26826-26925/com.example.ryan.jschtest I/System.out: Debug1
04-13 15:45:33.457 26826-26925/com.example.ryan.jschtest I/System.out: Debug2
04-13 15:45:33.470 26826-26925/com.example.ryan.jschtest I/System.out: Debug3
04-13 15:45:33.470 26826-26925/com.example.ryan.jschtest I/System.out: Debug4
04-13 15:45:33.470 26826-26925/com.example.ryan.jschtest I/System.out: Debug5
04-13 15:45:33.472 26826-26925/com.example.ryan.jschtest I/System.out: Connecting: 192.168.1.18:2223
04-13 15:45:34.008 26826-26925/com.example.ryan.jschtest I/System.out: Debug6
 04-13 15:45:34.013 26826-26925/com.example.ryan.jschtest I/System.out: Debug7
 04-13 15:45:34.013 26826-26925/com.example.ryan.jschtest I/System.out: Debug8
 04-13 15:45:34.013 26826-26925/com.example.ryan.jschtest I/System.out: Debug9
  04-13 15:45:34.013 26826-26925/com.example.ryan.jschtest I/System.out: Debug10
  04-13 15:45:34.014 26826-26925/com.example.ryan.jschtest I/System.out: Debug11
 04-13 15:45:34.076 26826-26925/com.example.ryan.jschtest I/System.out: Debug12
 04-13 15:45:35.112 26826-26925/com.example.ryan.jschtest I/System.out: exit-status: 0
 04-13 15:45:35.115 26826-26925/com.example.ryan.jschtest I/System.out:     Connect done

点击两次按钮后输出：

04-13 15:45:33.451 26826-26826/com.example.ryan.jschtest I/System.out:  --------------------------------- 
04-13 15:45:33.451 26826-26826/com.example.ryan.jschtest I/System.out:  CONNECT BUTTON CLICKED!
04-13 15:45:33.451 26826-26826/com.example.ryan.jschtest I/System.out:  --------------------------------- 
04-13 15:45:33.452 26826-26826/com.example.ryan.jschtest I/System.out: Done with Asynctask
04-13 15:45:33.452 26826-26925/com.example.ryan.jschtest I/System.out: Debug1
04-13 15:45:33.457 26826-26925/com.example.ryan.jschtest I/System.out: Debug2
04-13 15:45:33.470 26826-26925/com.example.ryan.jschtest I/System.out: Debug3
04-13 15:45:33.470 26826-26925/com.example.ryan.jschtest I/System.out: Debug4
04-13 15:45:33.470 26826-26925/com.example.ryan.jschtest I/System.out: Debug5
04-13 15:45:34.008 26826-26925/com.example.ryan.jschtest I/System.out: Debug6
04-13 15:45:34.013 26826-26925/com.example.ryan.jschtest I/System.out: Debug7
04-13 15:45:34.013 26826-26925/com.example.ryan.jschtest I/System.out: Debug8
04-13 15:45:34.013 26826-26925/com.example.ryan.jschtest I/System.out: Debug9
04-13 15:45:34.013 26826-26925/com.example.ryan.jschtest I/System.out: Debug10
04-13 15:45:34.014 26826-26925/com.example.ryan.jschtest I/System.out: Debug11
04-13 15:45:34.076 26826-26925/com.example.ryan.jschtest I/System.out: Debug12
04-13 15:45:35.112 26826-26925/com.example.ryan.jschtest I/System.out: exit-status: 0
04-13 15:45:35.115 26826-26925/com.example.ryan.jschtest I/System.out: Connect done
04-13 15:47:32.784 26826-26826/com.example.ryan.jschtest I/System.out:  --------------------------------- 
04-13 15:47:32.784 26826-26826/com.example.ryan.jschtest I/System.out:  CONNECT BUTTON CLICKED!
04-13 15:47:32.784 26826-26826/com.example.ryan.jschtest I/System.out:  --------------------------------- 
04-13 15:47:32.785 26826-26826/com.example.ryan.jschtest I/System.out: Done with Asynctask
04-13 15:47:32.785 26826-28694/com.example.ryan.jschtest I/System.out: Debug1
04-13 15:47:32.786 26826-28694/com.example.ryan.jschtest I/System.out: Debug2
04-13 15:47:32.786 26826-28694/com.example.ryan.jschtest I/System.out: Debug3
04-13 15:47:32.786 26826-28694/com.example.ryan.jschtest I/System.out: Debug4
04-13 15:47:32.786 26826-28694/com.example.ryan.jschtest I/System.out: Debug5
04-13 15:47:33.370 26826-28694/com.example.ryan.jschtest I/System.out: Debug6
04-13 15:47:33.370 26826-28694/com.example.ryan.jschtest I/System.out: Debug7
04-13 15:47:33.370 26826-28694/com.example.ryan.jschtest I/System.out: Debug8
04-13 15:47:33.370 26826-28694/com.example.ryan.jschtest I/System.out: Debug9
04-13 15:47:33.370 26826-28694/com.example.ryan.jschtest I/System.out: Debug10
04-13 15:47:33.371 26826-28694/com.example.ryan.jschtest I/System.out: Debug11
04-13 15:47:33.436 26826-28694/com.example.ryan.jschtest I/System.out: Debug12
04-13 15:47:34.467 26826-28694/com.example.ryan.jschtest I/System.out: exit-status: 0
04-13 15:47:34.468 26826-28694/com.example.ryan.jschtest I/System.out: Connect done

Answer 1

已解决：

public boolean connectComplete = false;

protected void buttonClick(View view)
{
    ConnectTask ayy = new ConnectTask();
    ayy.execute();
    while(!connectComplete) {
        try { Thread.sleep(100); } catch(Exception e) {System.out.println(e); e.printStackTrace; } 
    }
    ayy.cancel(true);
    connectComplete = false;
}

在ConnectTask中：

@Override
protected Void doInBackground(Void... params)
{
        MainActivity.connect();
        cancel(true);
        System.out.println("Connect done");
        connectComplete = true;
        return null;
}