public class MainActivity extends Activity {

  private BluetoothAdapter bluetoothAdapter;
  private TextView textView;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   textView = (TextView) findViewById(R.id.textView1);
   BluetoothManager manager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);


   bluetoothAdapter = manager.getAdapter();
   if (bluetoothAdapter == null || !bluetoothAdapter.isEnabled()) {
     Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
     startActivityForResult(intent, 1);
   }
   bluetoothAdapter.startLeScan(mLeScanCallback);

  }


  public void playVibator(Context context, long timeLong) {
   Vibrator vib = (Vibrator) context
      .getSystemService(Service.VIBRATOR_SERVICE);

   vib.vibrate(timeLong);
  }

  private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() {

   public void onLeScan(final BluetoothDevice device, final int rssi,
           final byte[] scanRecord) {
     int startByte = 2;
     boolean patternFound = false;
     // 寻找ibeacon
     while (startByte <= 5) {
      if (((int) scanRecord[startByte + 2] & 0xff) == 0x02
         && ((int) scanRecord[startByte + 3] & 0xff) == 0x15) {
        patternFound = true;
        break;
      }
      startByte++;
     }
     // 如果找到了的话
     if (patternFound) {
      String ibeaconName = device.getName();
      int txPower = (scanRecord[startByte + 24]);
      if (ibeaconName.equals("E-Beacon_CE6D94")) {
        System.out.println(calculateAccuracy(txPower, rssi));
        if (calculateAccuracy(txPower, rssi) > 1) {//这里是指iBeacon超过1米之后，textView字体变化
         textView.setText("设备有危险！");
         playVibator(MainActivity.this, 1000);
        } else {
         textView.setText("设备正常！");//在1米范围内
        }
      }
     }
   }
  };

  protected static double calculateAccuracy(int txPower, double rssi) {
   if (rssi == 0) {
     return -1.0; // if we cannot determine accuracy, return -1.
   }
   double ratio = rssi * 1.0 / txPower;
   if (ratio < 1.0) {
     return Math.pow(ratio, 10);
   } else {
     double accuracy = (0.89976) * Math.pow(ratio, 7.7095) + 0.111;
     return accuracy;
   }
  }
}