这个问题通常是由于蓝牙Socket连接被意外关闭引起的。为了解决这个问题，可以在程序的onPause()方法中注销蓝牙连接，然后在程序恢复时重新连接。以下是示例代码：

public class MainActivity extends Activity {
   private BluetoothAdapter mBluetoothAdapter;
   private BluetoothSocket mmSocket;
   private InputStream mmInStream;
   private OutputStream mmOutStream;
   private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
   private static String address = "00:00:00:00:00:00";

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);

       mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
       BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);

       try {
           mmSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
           mmSocket.connect();
           mmInStream = mmSocket.getInputStream();
           mmOutStream = mmSocket.getOutputStream();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }

   @Override
   protected void onPause() {
       super.onPause();

       try {
           mmSocket.close();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }

   @Override
   protected void onResume() {
       super.onResume();

       BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);

       try {
           mmSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
           mmSocket.connect();
           mmInStream = mmSocket.getInputStream();
           mmOutStream = mmSocket.getOutputStream();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }
}

在这个示例代码中，当程序进入暂停状态时，BluetoothSocket会被关闭。当程序恢复时，BluetoothSocket会重新连接并打开。这样可以确保每次程序运行时都能够建立有效的BluetoothSocket连接，并避免蓝牙连接意外关闭的问题。