Android realizes communication between mobile phone and microcontroller Bluetooth module

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public class MainActivity extends AppCompatActivity { 
 private Toolbar toolbar; 
 private TextView status; 
 private StringBuilder mstringbuilder; 
 private static final UUID MY_UUID=("00001101-0000-1000-8000-00805F9B34FB");//Not used BluetoothReceiver receiver; 
 BluetoothAdapter mBtAdapter; 
 BluetoothSocket mBtSocket; 
 private BlueToothTool client; 
 private ListView mListView; 
 private List<String> ListDevice; 
 private ArrayAdapter<String> mAdapter; 
 private Button mbutton; 
 private EditText editText; 
 private ProgressBar progressBar; 
 private LoopProgressBar loopProgressBar; 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
 (savedInstanceState); 
 setContentView(.activity_main); 
 toolbar=(Toolbar)findViewById(); 
 status=(TextView)findViewById(.textView2); 
 mListView=(ListView)findViewById(); 
 mbutton=(Button)findViewById(); 
 editText=(EditText)findViewById(); 
 progressBar=(ProgressBar)findViewById(); 
 (); 
 loopProgressBar=(LoopProgressBar)findViewById(); 
 ListDevice=new ArrayList<String>(); 
 mstringbuilder=new StringBuilder(); 
 setSupportActionBar(toolbar); 
 enablebluetooth(); 
 (new () { 
 @Override 
 public void onClick(View v) { 
  W= WriteTask(().toString()); 
 (); 
 } 
 }); 
 (new () { 
 @Override 
 public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
 ();//Stop search (); 
 String str = (position); 
 String macAdress = ("\\|")[1]; 
 BluetoothDevice device = (macAdress); 
 client=new BlueToothTool(device,handler); 
 try{ 
  (); 
 }catch (Exception e){ 
  (); 
 } 
 } 
 }); 
 } 
 
 /**
  *Bluetooth turned on and found
  */ 
 private void enablebluetooth(){ 
 mBtAdapter=(); 
 
 /**
  *if(!()){This can be enabled first, and it can be enabled at REQUEST_DISCOVERABLE, so that the enable and request can be completed together.
  // ();
  Intent enableIntent=new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
  startActivityForResult(enableIntent,REQUEST_ENABLE);
  }
  else {
  show("Bluetooth is turned on");
  }*/ 
 Intent enable = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE); 
 (BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300); 
 startActivityForResult(enable, REQUEST_DISCOVERABLE); 
 } 
 
 /**
  * Destruction incident, cancel the broadcast
  */ 
 @Override 
 protected void onDestroy() { 
 unregisterReceiver(receiver); 
 (); 
 } 
 private final Handler handler = new Handler() { 
 @Override 
 public void handleMessage(Message msg) { 
 switch () { 
 case BlueToothTool.CONNECT_FAILED: 
  show("Connection failed"); 
  try { 
  (); 
  } catch (Exception e) { 
  ("TAG", ()); 
  } 
  break; 
 case BlueToothTool.CONNECT_SUCCESS: 
  show("Connected successfully"); 
  (); 
  break; 
 case BlueToothTool.READ_FAILED: 
  show("Read failed"); 
  break; 
 case BlueToothTool.WRITE_FAILED: 
  show("Write failed"); 
  break; 
 case : 
  (()); 
  show(()); 
  break; 
 } 
 } 
 }; 
 /**
  * Request response result
  * @param requestCode
  * @param resultCode
  * @param data
  */ 
 @Override 
 protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
 switch (requestCode){ 
 
 /**
  *case REQUEST_ENABLE:
  if(requestCode!= Activity.RESULT_OK){
   show("Bluetooth not turned on");
  }
  else
   show("Bluetooth is turned on");
  break;*/ 
 case REQUEST_DISCOVERABLE: 
 if(resultCode==Activity.RESULT_CANCELED){ 
  show("Bluetooth not turned on"); 
 } 
 else 
  show("Bluetooth is on"); 
 break; 
 default: 
  break; 
 } 
 } 
 public boolean onCreateOptionsMenu(Menu menu){ 
 getMenuInflater().inflate(,menu); 
 return true; 
 } 
 private static final int REQUEST_ENABLE=1; 
 private static final int REQUEST_DISCOVERABLE=2; 
 
 /**
  * Register a broadcast event
  */ 
 @Override 
 public void onResume(){ 
 (); 
 IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND); 
 receiver = new BluetoothReceiver(); 
 registerReceiver(receiver, filter); 
 filter=new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED); 
 registerReceiver(receiver,filter); 
 } 
 
 /**
  * Broadcast
  */ 
 private class BluetoothReceiver extends BroadcastReceiver { 
 @Override 
 public void onReceive(Context context, Intent intent) { 
 String action = (); 
 if (BluetoothDevice.ACTION_FOUND.equals(action)) { 
 BluetoothDevice device = (BluetoothDevice.EXTRA_DEVICE); 
 String str = () + "|" + (); 
 if ((str) == -1)// Prevent repeated additions  (str); // Get the device name and mac address if (mAdapter != null) { 
  (); 
 } 
 showDevices(); 
 } 
 else if(BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)){ 
 (); 
 show("Stopped searching"); 
 } 
 
 } 
 }; 
 /**
  * Menu bar click event
  * @param item
  * @return
  */ 
 @Override 
 public boolean onOptionsItemSelected(MenuItem item) { 
 switch (()){ 
 case : 
 if(!()){ 
  show("Bluetooth not turned on"); 
 } 
 else { 
  (); 
  show("Looking for equipment"); 
  (); 
 } 
 break; 
 case : 
 (,"about Us",Toast.LENGTH_SHORT).show(); 
 break; 
 default: 
 } 
 return true; 
 } 
 private void showDevices() { 
 mAdapter = new ArrayAdapter<String>(this, .simple_list_item_1, 
 ListDevice); 
 (mAdapter); 
 } 
 /**
  * Update UI method
  * @param string
  */ 
 private void show(final String string){ 
 runOnUiThread(new Runnable() { 
 @Override 
 public void run() { 
 (string); 
 } 
 }); 
 } 
}

package ; 
 
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import ; 
 
/** 
 * Created by Fsl on 2017/12/22. 
 */ 
 
public class BlueToothTool { 
 private BluetoothDevice device; 
 private Handler mhandler; 
 BluetoothSocket socket; 
 static final int CONNECT_FAILED=1; 
 static final int CONNECT_SUCCESS=5; 
 static final int READ_FAILED=2; 
 static final int WRITE_FAILED=3; 
 static final int DATA=4; 
 private boolean isConnect=false; 
 
 public BlueToothTool(BluetoothDevice device,Handler handler){ 
 =device; 
 =handler; 
 } 
 /**
  *Distribute connection thread tasks
  */ 
 public void connect(){ 
 Thread thread = new Thread(new Runnable() { 
 @Override 
 public void run() { 
 BluetoothSocket tmp = null; 
 Method method; 
 try { 
  method = ().getMethod("createRfcommSocket", new Class[]{}); 
  tmp = (BluetoothSocket) (device, 1); 
 } catch (Exception e) { 
  setState(CONNECT_FAILED); 
  ("TAG", ()); 
 } 
 socket = tmp; 
 try { 
  (); 
  isConnect = true; 
  setState(CONNECT_SUCCESS); 
  Readtask readtask = new Readtask(); //Open the thread to read data after the connection is successful  (); 
 } catch (Exception e) { 
  setState(CONNECT_FAILED); 
  ("TAG", ()); 
 } 
 } 
 }); 
 new Thread(thread).start(); 
 } 
 /**
  *Develop thread reading tasks
  */ 
 public class Readtask extends Thread{ 
 @Override 
 public void run(){ 
 byte[] buffer = new byte[1024]; 
 int bytes; 
 InputStream inputStream ; //Create input stream to read data while (true) { 
 try { 
  inputStream = (); 
  if ((bytes = (buffer)) > 0) { 
  byte[] buf_data= new byte[bytes]; 
  for (int i = 0; i < bytes; i++) { 
  buf_data[i] = buffer[i]; 
  } 
  String s = new String(buf_data); 
  Message msg = (); 
   = DATA; 
   = s; 
  (msg); 
  } 
 } catch (IOException e) { 
  setState(READ_FAILED); 
  ("TAG", ()); 
  break; 
 } 
 } 
 
 if (socket != null) { 
 try { 
  (); 
 } catch (IOException e) { 
  ("TAG", ()); 
 } 
 } 
 } 
 } 
 /**
  *Develop thread writing tasks
  */ 
 public class WriteTask extends Thread{ 
 private String srt; 
 public WriteTask(String str){ 
 =str; 
 } 
 @Override 
 public void run(){ 
 OutputStream outputStream=null; 
 byte[] st=(); 
 try{ 
  outputStream=(); 
  (st); 
  }catch (Exception e){ 
  setState(WRITE_FAILED); 
  (); 
 } 
 } 
 
 } 
 
 
 private void setState(int mes){ 
 Message message=new Message(); 
 =mes; 
 (message); 
 
 } 
 /**
  *The following method has not been used yet
  */ 
 private byte[] getHexBytes(String message) { 
 int len = () / 2; 
 char[] chars = (); 
 String[] hexStr = new String[len]; 
 byte[] bytes = new byte[len]; 
 for (int i = 0, j = 0; j < len; i += 2, j++) { 
 hexStr[j] = "" + chars[i] + chars[i + 1]; 
 bytes[j] = (byte) (hexStr[j], 16); 
 } 
 return bytes; 
 } 
 
}