iBeacon使用蓝牙连接范围精确到1-3米

<uses-permission android:name="android.permission.VIBRATE" /><uses-permission android:name="android.permission.BLUETOOTH" /><uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

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;   }  }}