Android 活动重新加载时蓝牙连接丢失

我正在尝试连接蓝牙打印机设备，每次重新加载活动时，连接都会丢失。原因可能是什么？单击“下一步”按钮时，活动正在重新加载

代码如下：

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

    mActivity = Activity_Sales_Return.this;



        if(internet.HaveNetworkConnection()){
        try {
            mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();


                    try {

                        statusBT = false;
                        enableBT();
                        openBT();


                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
        }
        }
  void findBT() {

        try {

            Set<BluetoothDevice> pairedDevices = mBluetoothAdapter
                    .getBondedDevices();
            if (pairedDevices.size() > 0) {
                for (BluetoothDevice device : pairedDevices) {



                     if (device.getName().equalsIgnoreCase(bt_Name.trim()))              
              {
                        mmDevice = device;

                        break;
                    }

                }
            }
           showToast("Bluetooth Device Found");
        } catch (NullPointerException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    void enableBT(){
        try{

            if (mBluetoothAdapter == null) {

            }

            if (mBluetoothAdapter.isEnabled()) {
                findBT();
            }
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    // Tries to open a connection to the bluetooth printer device
    void openBT() throws IOException {
        try {
            // Standard SerialPortService ID
            UUID uuid = UUID.fromString("00001101-0000-1000-8000-
00805F9B34FB");
            System.out.println("====mmdevice: "+mmDevice);
            mmSocket = mmDevice.createRfcommSocketToServiceRecord(UUID
                    .fromString("00001101-0000-1000-8000-00805F9B34FB"));
            mmSocket.connect();
            mmOutputStream = mmSocket.getOutputStream();
            mmInputStream = mmSocket.getInputStream();

            beginListenForData();

            showToast("Bluetooth Opened");

        } catch (NullPointerException e) {
            showToast("Unable to connect device, Please try again.");
            e.printStackTrace();


        } catch (Exception e) {
            showToast("Unable to connect device, Please try again.");
            e.printStackTrace();

        }
    }

// After opening a connection to bluetooth printer device,
// we have to listen and check if a data were sent to be printed.
void beginListenForData() {
    try {
        final Handler handler = new Handler();

        // This is the ASCII code for a newline character
        final byte delimiter = 10;

        stopWorker = false;
        readBufferPosition = 0;
        readBuffer = new byte[1024];

        workerThread = new Thread(new Runnable() {
            public void run() {
                while (!Thread.currentThread().isInterrupted()
                        && !stopWorker) {

                    try {

                        int bytesAvailable = mmInputStream.available();
                        if (bytesAvailable > 0) {
                            byte[] packetBytes = new byte[bytesAvailable];
                            mmInputStream.read(packetBytes);
                            for (int i = 0; i < bytesAvailable; i++) {
                                byte b = packetBytes[i];
                                if (b == delimiter) {
                                    byte[] encodedBytes = new 
byte[readBufferPosition];
                                    System.arraycopy(readBuffer, 0,
                                            encodedBytes, 0,
                                            encodedBytes.length);
                                    final String data = new String(
                                            encodedBytes, "US-ASCII");
                                    readBufferPosition = 0;

                                    handler.post(new Runnable() {
                                        public void run() {
                                            showToast(data);
                                        }
                                    });
                                } else {
                                    readBuffer[readBufferPosition++] = b;
                                }
                            }
                        }

                    } catch (IOException ex) {
                        stopWorker = true;
                    }

                }
            }
        });

        workerThread.start();
    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
  }

 /*
 * This will send data to be printed by the bluetooth printer
 */
  void sendData() throws IOException {
    try {

        // the text typed by the user
        String msg = "hiii";
        msg += "\n";


         mmOutputStream.write(msg.getBytes());

        // tell the user data were sent
        showToast("Data Sent");


    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
  }

  // Close the connection to bluetooth printer.
  void closeBT() throws IOException {
    System.out.println("====mmOutputStream:"+mmOutputStream);
    if(mmOutputStream!=null && mmInputStream!=null && mmSocket!=null){
    try {

        System.out.println("===-----=mmOutputStream:"+mmOutputStream);
        stopWorker = true;
        mmOutputStream.close();
        mmInputStream.close();
        mmSocket.close();
        showToast("Bluetooth Closed");
    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
    }
 }
 @Override
protected void onDestroy() {
    super.onDestroy();

    if (internet.HaveNetworkConnection() ) {
    try {
        if(statusBT ){
            if (mService != null) 
                mService.stop();
        }else{
        closeBT();
        }

    } catch (IOException e) {
        e.printStackTrace();
    }
    }
    }


    public String uploadFile(String sourceFileUri) {
    System.out.println("lol");
    CheckInternetConnection internet = new CheckInternetConnection(
            Activity_Sales_Return.this);
    if (!internet.HaveNetworkConnection()) {
        return "No Internet";
    }

    String serverResponse = "";
    final String fileName = sourceFileUri;
    InputStream is = null;
    HttpURLConnection conn = null;
    DataOutputStream dos = null;
    String lineEnd = "\r\n";
    String twoHyphens = "--";
    String boundary = "*****";
    int bytesRead, bytesAvailable, bufferSize;
    byte[] buffer;
    int maxBufferSize = 1 * 1024 * 1024, serverResponseCode;
    File sourceFile = new File(sourceFileUri);
    if (!sourceFile.isFile()) {
        dialog.dismiss();
        Log.e("uploadFile",
                "Source File not exist :"
                        + Environment.getExternalStorageDirectory() + "/"
                        + Utility.SALE_FILE_NAME);
        return "";
    } else {
        try {

            // open a URL connection to the Servlet
            FileInputStream fileInputStream = new FileInputStream(
                    sourceFile);
            URL url = new URL(Utility.BASE_URL
                    + "?q=webservice/send_order&token=" + api_token);
            System.out.println("======url: "+url);

            // Open a HTTP connection to the URL
            conn = (HttpURLConnection) url.openConnection();
            conn.setDoInput(true); // Allow Inputs
            conn.setDoOutput(true); // Allow Outputs
            conn.setUseCaches(false); // Don't use a Cached Copy
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Connection", "Keep-Alive");
            conn.setRequestProperty("ENCTYPE", "multipart/form-data");
            conn.setRequestProperty("Content-Type",
                    "multipart/form-data;boundary=" + boundary);
            conn.setRequestProperty("xml", fileName);

            dos = new DataOutputStream(conn.getOutputStream());

            dos.writeBytes(twoHyphens + boundary + lineEnd);
            dos.writeBytes("Content-Disposition: form-data; name=\"xml\"; filename='"
                    + fileName + "'" + lineEnd);
            dos.writeBytes(lineEnd);

            // create a buffer of maximum size
            bytesAvailable = fileInputStream.available();
            bufferSize = Math.min(bytesAvailable, maxBufferSize);
            buffer = new byte[bufferSize];

            // read file and write it into form...
            bytesRead = fileInputStream.read(buffer, 0, bufferSize);
            while (bytesRead > 0) {
                dos.write(buffer, 0, bufferSize);
                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);
            }

            System.out.println("=======ff:" + toPrettyString(fileName, 4));
            // send multipart form data necesssary after file data...
            dos.writeBytes(lineEnd);
            dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

            // Responses from the server (code and message)
            serverResponseCode = conn.getResponseCode();
            String serverResponseMessage = conn.getResponseMessage();
            System.out.println("----------" + serverResponseMessage);
            if (serverResponseCode == 200) {
                runOnUiThread(new Runnable() {
                    public void run() {
                        showToast("Order Completed."); // Activity Reloading  
                                                       // here

                            try {

                                sendData();

                            } catch (IOException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                            }


                    }
                });
            }

            is = new DataInputStream(conn.getInputStream());
            int ch;
            StringBuffer sb = new StringBuffer();
            while ((ch = is.read()) != -1) {
                sb.append((char) ch);
            }
            serverResponse = sb.toString();
            fileInputStream.close();
            dos.flush();
            dos.close();
            is.close();
            dialog.dismiss();
            return serverResponse;
        } catch (Exception e) {
            e.printStackTrace();
        }
        dialog.dismiss();
        return "";
    }
}



next.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            try {
                      new Thread(new Runnable() {
                                    public void run() {
            final String serverResponse = uploadFile(Environment
  .getExternalStorageDirectory()+ "/"+ Utility.SALE_FILE_NAME);
}}}}}

@覆盖
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.layout\u sales\u return）；
mActivity=活动\销售\退货。此；
if（internet.HaveNetworkConnection（））{
试一试{
mBluetoothAdapter=BluetoothAdapter.getDefaultAdapter（）；
试一试{
statusBT=false；
enableBT（）；
openBT（）；
}捕获（IOEX异常）{
例如printStackTrace（）；
}
}
}
void findBT（）{
试一试{
设置pairedDevices=mBluetoothAdapter
.getBondedDevices（）；
如果（pairedDevices.size（）>0）{
用于（蓝牙设备：pairedDevices）{
if（device.getName（）.equalsIgnoreCase（bt_Name.trim（）））
{
mmDevice=设备；
打破
}
}
}
showToast（“找到蓝牙设备”）；
}捕获（NullPointerException e）{
e、 printStackTrace（）；
}捕获（例外e）{
e、 printStackTrace（）；
}
}
void enableBT（）{
试一试{
if（mBluetoothAdapter==null）{
}
if（mBluetoothAdapter.isEnabled（））{
findBT（）；
}
}捕获（例外e）{
e、 printStackTrace（）；
}
}
//尝试打开与蓝牙打印机设备的连接
void openBT（）引发IOException{
试一试{
//标准SerialPortService ID
UUID UUID=UUID.fromString（“00001101-0000-1000-8000-
00805F9B34FB”）；
System.out.println（“==mmdevice:+mmdevice”）；
mmSocket=mmDevice.createRfcommSocketToServiceRecord（UUID
.fromString（“000011101-0000-1000-8000-00805F9B34FB”）；
mmSocket.connect（）；
mmOutputStream=mmSocket.getOutputStream（）；
mmInputStream=mmSocket.getInputStream（）；
beginListenForData（）；
showToast（“蓝牙已打开”）；
}捕获（NullPointerException e）{
showToast（“无法连接设备，请重试”）；
e、 printStackTrace（）；
}捕获（例外e）{
showToast（“无法连接设备，请重试”）；
e、 printStackTrace（）；
}
}
//打开与蓝牙打印机设备的连接后，
//我们必须倾听并检查是否发送了数据进行打印。
void beginListenForData（）{
试一试{
最终处理程序=新处理程序（）；
//这是换行符的ASCII码
最后一个字节分隔符=10；
stopWorker=false；
readBufferPosition=0；
readBuffer=新字节[1024]；
workerThread=新线程（new Runnable（））{
公开募捐{
而（！Thread.currentThread（）.isInterrupted（）
&&！停车工人）{
试一试{
int bytesavable=mmInputStream.available（）；
如果（字节可用>0）{
byte[]packetBytes=新字节[bytesAvailable]；
mmInputStream.read（packetBytes）；
for（int i=0；i