软键按钮

Question

我们正在尝试构建一个Android应用程序，作为机器人的遥控器。我们已经完成了很多代码，但是关键是存在问题。我们使用软键作为应用程序的基本结构，我们对其进行了修改，以便方向键可以远程控制机器人。但是我们的代码存在问题。当我们按下（例如）“向上”按钮时，应用程序即使在我们释放密钥后也会不断发出“向上”信号。有没有办法，我们可以在释放按钮后停止信号？请提前建议，谢谢你的帮助。

我们代码的一部分：

private boolean genericClick( View v, boolean longClick, MotionEvent me ) {
        if( me != null ) {
            Toast.makeText( this, "Warning: MotionEvent is broken", Toast.LENGTH_LONG );
        }

        // send an intent to the main window
        int keyid = 0;
        Globals app = (Globals)getApplication();
        boolean hide = auto_hide;

        switch( v.getId() ) {
            case R.id.home:
                Log.v("MyActivity", "Wifi");        


try {  

s = new Socket("142.58.160.178", 5000);


   BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));


   writer.write("Connect");

   writer.flush();

   writer = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));

} catch (UnknownHostException e) {

// TODO Auto-generated catch block





           Toast.makeText( this, "Connection Failed", Toast.LENGTH_LONG );

e.printStackTrace();

} catch (IOException e) {


// TODO Auto-generated catch block

           Toast.makeText( this, "Connection Failed", Toast.LENGTH_LONG );

e.printStackTrace();



}


                //app.doHomeAction( longClick );
                break;

            case R.id.extra_center:
                keyid = K.KEYID_DPAD_CENTER;
                //Log.v("MyActivity", "stop");
                mHandler.removeCallbacks(mUpdateTask);
                hide = false;
                break;

            case R.id.extra_up:
                keyid = K.KEYID_DPAD_UP;
                //Log.v("MyActivity", "up1");
                direction=0; //up
                mHandler.removeCallbacks(mUpdateTask);
                mHandler.postAtTime(mUpdateTask, SystemClock.uptimeMillis() + 50);
                hide = false;
                break;

            case R.id.extra_down:
                keyid = K.KEYID_DPAD_DOWN;
                //Log.v("MyActivity", "down1");
                direction=1;    


                mHandler.removeCallbacks(mUpdateTask);
                mHandler.postAtTime(mUpdateTask, SystemClock.uptimeMillis() + 50);
                hide = false;
                break;

            case R.id.extra_left:
                keyid = K.KEYID_DPAD_LEFT;
                //Log.v("MyActivity", "left1");
                direction=2;
                mHandler.removeCallbacks(mUpdateTask);
                mHandler.postAtTime(mUpdateTask, SystemClock.uptimeMillis() + 50);
                hide = false;
                break;

            case R.id.extra_right:
                keyid = K.KEYID_DPAD_RIGHT;
                //Log.v("MyActivity", "right1");
                direction=3;
                mHandler.removeCallbacks(mUpdateTask);
                mHandler.postAtTime(mUpdateTask, SystemClock.uptimeMillis() + 50);
                hide = false;
                break;
}
}

private Runnable mUpdateTask = new Runnable()
    {
        public void run()
        {
            switch(direction){
            case 0:
                Log.i("repeatBtn", "Up");          

if (s!=null){            

    try {

   BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));

   writer.write("U");

   writer.flush();

    } catch (UnknownHostException e) {        

     // TODO Auto-generated catch block

     e.printStackTrace();

    } catch (IOException e) {

     // TODO Auto-generated catch block

     e.printStackTrace();

    }
}

    break;
            case 1:
              // Log.i("repeatBtn", "Down");          

if (s!=null){

    try {

   BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));

   writer.write("D");

   writer.flush();

    } catch (UnknownHostException e) {        

     // TODO Auto-generated catch block

     e.printStackTrace();

    } catch (IOException e) {

     // TODO Auto-generated catch block

     e.printStackTrace();

    }
}

    break;
            case 2:
               // Log.i("repeatBtn", "Left");  

if (s!=null){                

    try {

   BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));

   writer.write("L");

   writer.flush();

    } catch (UnknownHostException e) {        

     // TODO Auto-generated catch block

     e.printStackTrace();

    } catch (IOException e) {

     // TODO Auto-generated catch block

     e.printStackTrace();

    }

}

break;

            case 3:
               // Log.i("repeatBtn", "Right");          

if (s!=null){              

    try {

   BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));

   writer.write("R");

   writer.flush();

    } catch (UnknownHostException e) {        


     // TODO Auto-generated catch block


     e.printStackTrace();

    } catch (IOException e) {


     // TODO Auto-generated catch block


     e.printStackTrace();

    }

}

break;

            }

            mHandler.postAtTime(this, SystemClock.uptimeMillis() + 50);      

        }
    };   

Answer 1

据我所知，除了按中心键外，没有任何代码能够一劳永逸地删除回调。在mUpdateTask结束时，回调会再次将自身注入Handler队列，这解释了重复。

如果您希望能够在按下按钮时发送事件，则可以使用OnTouchListener作为按钮，因为它可以对按下和释放做出反应。 OnClickListener只能对按下+释放做出反应。