如何清除关闭的Android应用程序

Question

我从谷歌服用了大量代码后创建了一个应用程序。将它们放在一起后，应用程序似乎运行安静。当我启动应用程序时，它请求蓝牙访问。一旦提供，它会显示可用的蓝牙连接列表。点击后，它连接到Arduino板（HC-05模块）并发送命令。一切都很好，直到现在。

现在，当我使用Back键关闭应用程序时，应用程序仍然保持连接打开状态。在Arduino上，While（Serial1.available）返回true。

当我使用断开按钮断开连接时，它将关闭连接，并再次连接到电路板不会发送任何命令，而只是连接状态已连接。

为了使它工作，我必须重新安装使用android studio的应用程序，然后打开连接，它完美的工作。

我的疑惑是：在关闭应用程序之前是否有必须清除的东西？由于应用程序使用片段，我不知道如何清除所有的缓存，堆栈或其他任何东西。我已经添加了下面的代码来检查。

请帮忙。

public class MainActivityFragment extends Fragment { 

    private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); 
    private static BluetoothAdapter mAdapter = null; 
    private static OutputStream outStream = null; 
    private int message = 0; 
    private int aButton = 1; 
    private int bButton = 1; 
    private int cButton = 1; 
    private int dButton = 1; 
    private int eButton = 1; 
    private int fButton = 1; 
    private int gyButton = 0; 
    private float xcoord = 0; 
    private float ycoord = 0; 

    private int f1; 
    private int s2; 
    private int t3; 
    private int f4; 
    private int CS; 

    private int case_ = 0; 
    private int xPower = 0; // processed x-y power 
    private int yPower = 0; 
    private float initX = 0; // initial touch position 
    private float initY = 0; 
    private float origX = 0; // joystick button locations 
    private float origY = 0; 
    private long data_ = 0; 

    private double joyPower = 0; 
    private double joyAngle = 0; 

    private static BluetoothSocket mSocket = null; 
    private static Timer timer; 
    private final Handler handler = new Handler(); 
    private static BluetoothDevice device; 
    private ImageView btButton; 
    private ImageView disconnectButton; 
    private static TimerTask sendMessage; 
    private static boolean isSchedule = false; 

    public MainActivityFragment() { 

    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 

     final View rootView = inflater.inflate(R.layout.fragment_main, container, false); 
     final TextView serO = (TextView) rootView.findViewById(R.id.serialOut); 
     final Vibrator vibr = (Vibrator) getActivity().getSystemService(Context.VIBRATOR_SERVICE); 

     timer = new Timer(); 
     sendMessage = new TimerTask() { 
      @Override 
      public void run() { 
       handler.post(new Runnable() { 
        @Override 
        public void run() { 
         if (outStream != null) { 

          try { 
           message = 100; 
           outStream.write(message); 
          } catch (Exception e) { 
          } 
         } 
        } 
       }); 
      } 
     }; 
     // Get Bluetooth adapter 
     mAdapter = BluetoothAdapter.getDefaultAdapter(); 
     checkBTState(); 

     // Set aButton = 1 when A is pressed 
     final ImageButton a = (ImageButton) rootView.findViewById(R.id.a); 
     //Button a = (Button) rootView.findViewById(R.id.a); 
     a.setOnTouchListener(new View.OnTouchListener() { 
      @Override 
      public boolean onTouch(View v, MotionEvent event) { 
       switch (event.getAction()) { 
        case MotionEvent.ACTION_DOWN: 
         aButton = 0; 
         //Toast.makeText(getActivity().getBaseContext(), "A Action Down" + aButton, Toast.LENGTH_LONG).show(); 
         Vibrator vibr = (Vibrator) getActivity().getSystemService(Context.VIBRATOR_SERVICE); 
         vibr.vibrate(50); 
         a.setImageResource(R.drawable.white_bg); 
         return true; 
        case MotionEvent.ACTION_UP: 
         aButton = 1; 
         a.setImageResource(R.drawable.trans_bg); 
         return true; 
       } 
       return false; 
      } 
     }); 

    private void checkBTState() { 
     if (mAdapter == null) { 
      Toast.makeText(getActivity().getApplicationContext(), "Bluetooth Not Supported", Toast.LENGTH_SHORT).show(); 
     } else { 
      if (!mAdapter.isEnabled()) { 
       startActivityForResult(new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE), 1); 
      } 
     } 
    } 

    private static BluetoothSocket createBluetoothSocket(BluetoothDevice device) throws IOException { 
     if (Build.VERSION.SDK_INT >= 10) { 
      try { 
       final Method m = device.getClass().getMethod("createInsecureRfcommSocketToServiceRecord", new Class[]{UUID.class}); 
       return (BluetoothSocket) m.invoke(device, MY_UUID); 
      } catch (Exception e) { 

      } 
     } 
     return device.createInsecureRfcommSocketToServiceRecord(MY_UUID); 
    } 

    public static void connect(String address, Context context) { 
     try { 
      device = mAdapter.getRemoteDevice(address); 
     } catch (Exception e) { 
      Toast.makeText(context, "Invalid Address", Toast.LENGTH_LONG).show(); 
     } 

     try { 
      mSocket = createBluetoothSocket(device); 
     } catch (Exception e) { 

     } 

     mAdapter.cancelDiscovery(); 

     try { 
      // try connecting to socket 
      mSocket.connect(); 
     } catch (Exception e) { 
      try { 
       mSocket.close(); 
      } catch (Exception e1) { 
       Log.e("E4", "Socket Connection Exception"); 
      } 
     } 

     try { 
      outStream = mSocket.getOutputStream(); 
      if (!isSchedule) { 
       timer.schedule(sendMessage, 0, 500); 
       isSchedule = true; 
      } else { 
       Log.e("Timer", "Timer already schedule"); 
      } 
      Toast.makeText(context, "Connection Established", Toast.LENGTH_SHORT).show(); 
     } catch (IOException e) { 
     } 
    } 


    public static boolean isConnected() { 
     // Check if the phone has already connected to bluetooth device 
     return device != null; 
    } 

    private void disconnectDevice() { 
     if (device != null) { 
      device = null; 

      try { 
       outStream.close(); 
      } catch (Exception e) { 
      } 
      outStream = null; 
      mSocket = null; 
      Toast.makeText(getActivity(), "Bluetooth Device Disconnected", Toast.LENGTH_SHORT).show(); 
     } 
    } 
} 

Answer 1

做你的代码中onStop()

见The Activity Lifecycle

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