蓝牙的使用
安卓上的蓝牙 一种是传统蓝牙 搜索 连接 通信 感觉耗时有点长 支持低版本的安卓系统
还有一种是 低功耗蓝牙 基于安卓4.3系统 应该就是根据ios系统的ibeacon蓝牙改过来的 在不需要蓝牙通信的情况下 感觉还是速度挺快的 缺点就是因为是依据ios系统 所以安卓系统的api不是很多 苹果上可以一次直接获取满足条件的所有蓝牙设备 并且可以获取信号量级 距离等大概数据 而安卓系统则只能获得基本数据 信号量级 距离需要转换 并且没有特定周期 个人测试安卓系统蓝牙搜索是随机的 如果同时搜索多个设备 虽然每个用时都很少 可能几毫秒 但是所有都一次搜索完成的周期还不是确定
首先 要有2个蓝牙权限
<uses-permissionandroid:name="android.permission.BLUETOOTH"/>
<uses-permissionandroid:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-permissionandroid:name="android.permission.BLUETOOTH_ADMIN"/>
有几个蓝牙的基本参数 major minor proxomityUUid 设备的编号 bludtoothAddress 蓝牙的地址 txPower 在计算用要用到
rssi 信号强度 distance 根据强度计算出的距离 受信号自身波动和环境相应较大 可以对信号做均值处理
放一个ibeacon的类
public class iBeaconClass { static public class iBeacon { public String name; public int major; public int minor; public String proximityUuid; public String bluetoothAddress; public int txPower; public int rssi; public String distance; public static iBeacon fromScanData(BluetoothDevice device, int rssi, byte[] scanData) { int startByte = 2; boolean patternFound = false; while (startByte <= 5) { if (((int) scanData[startByte + 2] & 0xff) == 0x02 && ((int) scanData[startByte + 3] & 0xff) == 0x15) { // yes! This is an iBeacon patternFound = true; break; } else if (((int) scanData[startByte] & 0xff) == 0x2d && ((int) scanData[startByte + 1] & 0xff) == 0x24 && ((int) scanData[startByte + 2] & 0xff) == 0xbf && ((int) scanData[startByte + 3] & 0xff) == 0x16) { iBeacon iBeacon = new iBeacon(); iBeacon.major = 0; iBeacon.minor = 0; iBeacon.filter = 0; iBeacon.proximityUuid = "00000000-0000-0000-0000-000000000000"; iBeacon.txPower = -55; iBeacon.distance = String.format("%.2f", calculateDistance(iBeacon.txPower, rssi)); return iBeacon; } else if (((int) scanData[startByte] & 0xff) == 0xad && ((int) scanData[startByte + 1] & 0xff) == 0x77 && ((int) scanData[startByte + 2] & 0xff) == 0x00 && ((int) scanData[startByte + 3] & 0xff) == 0xc6) { iBeacon iBeacon = new iBeacon(); iBeacon.major = 0; iBeacon.minor = 0; iBeacon.filter = 0; iBeacon.proximityUuid = "00000000-0000-0000-0000-000000000000"; iBeacon.txPower = -55; iBeacon.distance = String.format("%.2f", calculateDistance(iBeacon.txPower, rssi)); return iBeacon; } startByte++; } if (patternFound == false) { // This is not an iBeacon return null; } iBeacon iBeacon = new iBeacon(); iBeacon.major = (scanData[startByte + 20] & 0xff) * 0x100 + (scanData[startByte + 21] & 0xff); iBeacon.minor = (scanData[startByte + 22] & 0xff) * 0x100 + (scanData[startByte + 23] & 0xff); iBeacon.txPower = (int) scanData[startByte + 24]; // this one is signed iBeacon.rssi = rssi; iBeacon.filter = 0; iBeacon.distance = String.format("%.2f", calculateDistance(iBeacon.txPower, rssi)); // AirLocate: // 02 01 1a 1a ff 4c 00 02 15 # Apple's fixed iBeacon advertising prefix // e2 c5 6d b5 df fb 48 d2 b0 60 d0 f5 a7 10 96 e0 # iBeacon profile uuid // 00 00 # major // 00 00 # minor // c5 # The 2's complement of the calibrated Tx Power // Estimote: // 02 01 1a 11 07 2d 24 bf 16 // 394b31ba3f486415ab376e5c0f09457374696d6f7465426561636f6e00000000000000000000000000000000000000000000000000 try { byte[] proximityUuidBytes = new byte[16]; System.arraycopy(scanData, startByte + 4, proximityUuidBytes, 0, 16); String hexString = bytesToHexString(proximityUuidBytes); StringBuilder sb = new StringBuilder(); sb.append(hexString.substring(0, 8)); sb.append("-"); sb.append(hexString.substring(8, 12)); sb.append("-"); sb.append(hexString.substring(12, 16)); sb.append("-"); sb.append(hexString.substring(16, 20)); sb.append("-"); sb.append(hexString.substring(20, 32)); iBeacon.proximityUuid = sb.toString(); } catch (Exception e) { e.printStackTrace(); } if (device != null) { iBeacon.bluetoothAddress = device.getAddress(); iBeacon.name = device.getName(); } return iBeacon; } public static String bytesToHexString(byte[] src) { StringBuilder stringBuilder = new StringBuilder(""); if (src == null || src.length <= 0) { return null; } for (int i = 0; i < src.length; i++) { int v = src[i] & 0xFF; String hv = Integer.toHexString(v); if (hv.length() < 2) { stringBuilder.append(0); } stringBuilder.append(hv); } return stringBuilder.toString(); } /** * 估算用户设备到ibeacon的距离 * * @param txPower * @param rssi * @return */ 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; } } // 使用这个测量距离 public static double calculateDistance(int txPower, int rssi) { // 信号值得绝对值. int absRssi = Math.abs(rssi); // txPower 一米值. 暂时使用经验值 59 .需要替换成自己的真实值. txPower = 59; double power = (absRssi - txPower) / (10 * 2.0); return Math.pow(10, power); } // public 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 = (0.42093) * Math.pow(ratio, 6.9476) + 0.54992; // return accuracy; // } // } }
网上有很多计算距离的方法 随便找了一个 这个类可以根据安卓的蓝牙参数转换出我们需要的参数
在activity中
@Override protected void onCreate(Bundle savedInstanceState) {
BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE); mBluetoothAdapter = bluetoothManager.getAdapter();
startleScan();
}
private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() { @Override public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) { Log.d("device", device.getAddress()); iBeaconClass.iBeacon ibeacon = iBeaconClass.fromScanData(device, rssi, scanRecord); } }; private void startleScan() { mBluetoothAdapter.startLeScan(mLeScanCallback); }
private void stop() { mBluetoothAdapter.stopLeScan(mLeScanCallback); }
系统自带的蓝牙搜索 大概几毫秒收到一个信号 但是发送信号设备的发送周期 多个设备同时发送 接收就是随机的 不像ios系统周期一秒返回全部的蓝牙设备信号强度 这个要自己处理下 网上的第三方 也可以用
compile 'org.altbeacon:android-beacon-library:2+'
其实根原生的差不多 也是确定周期 然后按周期返回信号强度 但是周期内也不能保证每个设备都接收到
有个问题就是蓝牙的搜索要在系统授权定位权限以后才能搜到数据 要不然是收不到数据的 而且要手机带蓝牙模块安卓系统4.3才开始支持ibecaon
所以先处理权限 在处理是否支持蓝牙
private void checkPermissions() { BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter(); if (!bluetoothAdapter.isEnabled()) {//如果adapter为空说明 没有蓝牙模块ø dialog(); //提示开启蓝牙开关 return; } else { beaconManager = BeaconManager.getInstanceForApplication(this); beaconManager.getBeaconParsers().add(new BeaconParser().setBeaconLayout(IBEACON_FORMAT)); beaconManager.bind(this); } String[] permissions = {Manifest.permission.ACCESS_FINE_LOCATION}; //如果没有定位权限 蓝牙什么也搜不到 List<String> permissionDeniedList = new ArrayList<>(); for (String permission : permissions) { int permissionCheck = ContextCompat.checkSelfPermission(this, permission); if (permissionCheck == PackageManager.PERMISSION_GRANTED) { beaconManager = BeaconManager.getInstanceForApplication(this); beaconManager.getBeaconParsers().add(new BeaconParser().setBeaconLayout(IBEACON_FORMAT)); beaconManager.bind(this); } else { permissionDeniedList.add(permission); } } if (!permissionDeniedList.isEmpty()) { String[] deniedPermissions = permissionDeniedList.toArray(new String[permissionDeniedList.size()]); ActivityCompat.requestPermissions(this, deniedPermissions, REQUEST_CODE_PERMISSION_LOCATION); } } private void dialog() { Log.d("boolean", "" + mBluetoothAdapter.isEnabled()); if (!mBluetoothAdapter.isEnabled()) { Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); startActivityForResult(enableBtIntent, 10); } } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == 10) { if (resultCode == RESULT_OK) { beaconManager = BeaconManager.getInstanceForApplication(this); beaconManager.getBeaconParsers().add(new BeaconParser().setBeaconLayout(IBEACON_FORMAT)); beaconManager.bind(this); } else { Toast.makeText(this, "请开启蓝牙", Toast.LENGTH_LONG).show(); } } }