Need BLUETOOTH PRIVILEGED permission以及requestMtu导致蓝牙断连问题
在部分Android手机上,当连接上GATTService后直接requestMtu有可能会造成蓝牙连接中断,随后继续重新连接会报错Need BLUETOOTH PRIVILEGED permission
1 //扫描成功后连接gatt 2 BluetoothDevice mRemoteDevice = mBluetoothAdapter.getRemoteDevice(result.getDevice().getAddress()); 3 BluetoothGatt mBluetoothGatt = mRemoteDevice.connectGatt(getContext(), false, bluetoothGattCallback);
在 BluetoothGattCallback 监听的 onConnectionStateChange(BluetoothGatt gatt, int status, int newState)方法中直接requestMtu(512) 会直接导致蓝牙断开连接
1 private int setMTUInt = 512; 2 3 4 @Override 5 public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) { 6 super.onConnectionStateChange(gatt, status, newState); 7 8 if (newState == BluetoothProfile.STATE_CONNECTED) { //// 连接成功 9 //虽然这里的boolean会为true但是实际上会失败,并且导致蓝牙断开链接 10 boolean requestMtu = gatt.requestMtu(setMTUInt); 11 Log.e(TAG,"设置 requestMtu:"+requestMtu); 12 13 } else if (newState == BluetoothProfile.STATE_DISCONNECTED) { // 连接断开 14 //清除缓存,防止Need BLUETOOTH PRIVILEGED permission 15 refreshDeviceCache(); 16 //将MTU的值减少,值可以随意设置 17 setMTUInt -= 100; 18 // 关闭GATT客户端 19 mBluetoothGatt.close(); 20 } 21 }
在监听的onMtuChanged(BluetoothGatt gatt, int mtu, int status)方法中,确认mtu设置成功后,再去请求特征值
1 @Override 2 public void onMtuChanged(BluetoothGatt gatt, int mtu, int status) { 3 super.onMtuChanged(gatt, mtu, status); 4 5 // 开始查找GATT服务器提供的服务 6 gatt.discoverServices(); 7 8 }
随后在监听的onServicesDiscovered(BluetoothGatt gatt, int status)方法中设置特征
@Override public void onServicesDiscovered(BluetoothGatt gatt, int status) { super.onServicesDiscovered(gatt, status); if (status == BluetoothGatt.GATT_SUCCESS) { //设置特征值 requestCharacteristic(); } }
清除缓存的方法,gatt本身有提供清除缓存方法,但是不给外部直接调用,所以使用反射的方式进行调用,建议在每次开启扫描设备时也清除一下缓存,防止链接过其他设备后直接链接新设备报错 java.lang.SecurityException: Need BLUETOOTH PRIVILEGED permission: Neither user 10208 nor current process has android.permission.BLUETOOTH_PRIVILEGED.
1 public boolean refreshDeviceCache() { 2 if (mBluetoothGatt != null) { 3 Log.e(TAG,"清除缓存 refreshDeviceCache"); 4 try { 5 BluetoothGatt localBluetoothGatt = mBluetoothGatt; 6 Method localMethod = localBluetoothGatt.getClass().getMethod( 7 "refresh", new Class[0]); 8 if (localMethod != null) { 9 boolean bool = ((Boolean) localMethod.invoke( 10 localBluetoothGatt, new Object[0])).booleanValue(); 11 return bool; 12 } 13 } catch (Exception localException) { 14 Log.i(TAG, "An exception occured while refreshing device"); 15 } 16 } 17 return false; 18 }