Android 低功耗蓝牙

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1.BLE权限定义

Android低功耗蓝牙只支持4.3（API 18）以后的设备
    <uses-permission android:name="android.permission.BLUETOOTH"/>
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
如果你只想你的APP运行在支持低功耗蓝牙的设备上你可以在manifest上加入
    <uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>

或者在运行时加入以下代码:

if (!getPackageManager().hasSystemFeature(
PackageManager.FEATURE_BLUETOOTH_LE)) {
    Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
    finish();
}

2.配置蓝牙

2.1.获取BluetoothAdapter

final BluetoothManager bluetoothManager =
    (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();

2.2.打开蓝牙

private BluetoothAdapter mBluetoothAdapter;
...
// Ensures Bluetooth is available on the device and it is enabled. If not,
// displays a dialog requesting user permission to enable Bluetooth.
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
    Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}

3.查找蓝牙设备

private BluetoothAdapter.LeScanCallback mLeScanCallback =
        new BluetoothAdapter.LeScanCallback() {
    @Override
    public void onLeScan(final BluetoothDevice device, int rssi,
            byte[] scanRecord) {
        runOnUiThread(new Runnable() {
           @Override
           public void run() {
           
           // 通过 device.getName(),device.getAddress()获取到蓝牙设备名称和地址
           }
       });
   }
};


 private BluetoothAdapter mBluetoothAdapter;
    private boolean mScanning;
    private Handler mHandler;

    // Stops scanning after 10 seconds.
    private static final long SCAN_PERIOD = 10000;
    ...
    private void scanLeDevice(final boolean enable) {
        if (enable) {
            // Stops scanning after a pre-defined scan period.
            mHandler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    mScanning = false;
                    mBluetoothAdapter.stopLeScan(mLeScanCallback);
                }
            }, SCAN_PERIOD);

            mScanning = true;
            mBluetoothAdapter.startLeScan(mLeScanCallback);
        } else {
            mScanning = false;
            mBluetoothAdapter.stopLeScan(mLeScanCallback);
        }
        ...
    }

3.连接蓝牙设备

private final BluetoothGattCallback mGattCallback =
            new BluetoothGattCallback() {
        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status,
                int newState) {
            String intentAction;
            if (newState == BluetoothProfile.STATE_CONNECTED) {
            // 连接成功后要查询蓝牙服务
               Log.i(TAG, "Attempting to start service discovery:" +
                        mBluetoothGatt.discoverServices());
                

            } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
               
            }
        }

        @Override
        // New services discovered
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            if (status == BluetoothGatt.GATT_SUCCESS) {
               //发现蓝牙服务后可获取到
               
            List<BluetoothGattService> gattServices=mBluetoothGatt.getServices();
               
            } else {
                Log.w(TAG, "onServicesDiscovered received: " + status);
            }
        }

        @Override
        // Result of a characteristic read operation
        public void onCharacteristicRead(BluetoothGatt gatt,
                BluetoothGattCharacteristic characteristic,
                int status) {
            if (status == BluetoothGatt.GATT_SUCCESS) {
                broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
            }
        }
     ...
    };
    
BluetoothGatt mBluetoothGatt = device.connectGatt(this, false, mGattCallback);

   // Previously connected device.  Try to reconnect.
        if (mBluetoothDeviceAddress != null && address.equals(mBluetoothDeviceAddress)
                && mBluetoothGatt != null) {
            Log.d(TAG, "Trying to use an existing mBluetoothGatt for connection.");
            if (mBluetoothGatt.connect()) {
                mConnectionState = STATE_CONNECTING;
                return true;
            } else {
                return false;
            }
        }

4.获取蓝牙属性

在回调方法onServicesDiscovered中获取蓝牙设备的Service和Characteristic;

    @Override
        // New services discovered
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            if (status == BluetoothGatt.GATT_SUCCESS) {
             
            List<BluetoothGattService> gattServices=mBluetoothGatt.getServices();
            List<BluetoothGattCharacteristic> gattCharacteristics =
                    gattService.getCharacteristics();
               
            } else {
                Log.w(TAG, "onServicesDiscovered received: " + status);
            }
        }

5.对蓝牙Characteristic进行操作

5.1 写操作（W - Write）

    byte[] dataToWrite;
    characteristic.setValue(dataToWrite)
    mBluetoothGatt.writeCharacteristic(characteristic);

//写操作完成会回调
 @Override
     public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
     if (status == BluetoothGatt.GATT_SUCCESS) {
 //写入成功
            }
            else {
             //写入失败  
            }
     
     }

5.2 读操作（R - Read）

 mBluetoothGatt.readCharacteristic(characteristic);

//读操作会回调
 @Override
public void onCharacteristicRead(BluetoothGatt gatt,
                                         BluetoothGattCharacteristic characteristic, int status) {
         // we got response regarding our request to fetch characteristic value
            if (status == BluetoothGatt.GATT_SUCCESS) {
                // and it success, so we can get the value
                //在此处取值
                 byte[] rawValue = characteristic.getValue();
            }
        }

5.3 通知或指示操作（I - Indication or N - Notify）

  boolean success = mBluetoothGatt.setCharacteristicNotification(ch, enabled);
        if (!success) {
            Log.e("------", "Seting proper notification status for characteristic failed!");
        }

        BluetoothGattDescriptor descriptor = ch.getDescriptor(UUID.fromString("00002902-0000-1000-8000-00805f9b34fb"));
// 启用或停用  I - Indication or N - Notify
//      BluetoothGattDescriptor.ENABLE_INDICATION_VALUE
//      BluetoothGattDescriptor.DISABLE_NOTIFICATION_VALUE
    descriptor.setValue(enabled ?
    BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE : BluetoothGattDescriptor.DISABLE_NOTIFICATION_VALUE);
 mBluetoothGatt.writeDescriptor(descriptor);

// 通知或指示操作会回调

   @Override
        public void onCharacteristicChanged(BluetoothGatt gatt,
                                            BluetoothGattCharacteristic characteristic) {
            // characteristic's value was updated due to enabled notification, lets get this value
            // the value itself will be reported to the UI inside getCharacteristicValue

            
        }

6.断开连接,关闭连接

 mBluetoothGatt.disconnect();

public void close() {
    if (mBluetoothGatt == null) {
        return;
    }
    mBluetoothGatt.close();
    mBluetoothGatt = null;
}