我在两家公司都用到了app与BLE设备通讯，当时也是什么都不懂，在网上各种搜索，各种查资料，总算弄出来了。在这里记录下来，希望对有需要的人有些帮助。

  1.检测手机是否支持蓝牙4.0（一般手机4.3以上的android系统都支持）

   

<span style="font-size:14px;"> if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {showMsg(R.string.ble_not_supported);finish();}</span>

   2.检测蓝牙是否打开，提示用户打开蓝牙（在此之前需要加相应的权限）
      添加权限：

<span style="font-size:14px;">    <uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/><uses-permission android:name="android.permission.BLUETOOTH"/><uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/></span>

       获取蓝牙适配器

        

   <span style="font-size:14px;">final BluetoothManager bluetoothManager =(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);bluetoothAdapter = bluetoothManager.getAdapter();
如果蓝牙处于关闭状态，则通过下面代码提示用户启动蓝牙：
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
</span>

      3.启动关闭蓝牙，获取蓝牙状态
          

           判断蓝牙状态：bluetoothAdapter.isEnabled()

           开启蓝牙：bluetoothAdapter.enable();

           关闭蓝牙：bluetoothAdapter.disable();

      

      4.蓝牙启动后，就该搜索设备了

           

           开启搜索： bluetoothAdapter.startLeScan(mLeScanCallback);

           停止搜索： bluetoothAdapter.stopLeScan(mLeScanCallback);

           搜索回调：

                     

          private BluetoothAdapter.LeScanCallback mLeScanCallback =new BluetoothAdapter.LeScanCallback() {@Overridepublic void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {runOnUiThread(new Runnable() {@Overridepublic void run() {//在这里将搜到的设备显示到界面}});}};

          

        5.建立连接

         

           

          public boolean connect(BluetoothDevice  device ) {if (device == null) {Log.w(TAG, "Device not found.  Unable to connect.");return false;}mBluetoothGatt = device.connectGatt(this, false, mGattCallback);return true;}

                       
              连接时需要注册一个回调接口：

    private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {//检测连接状态变化
@Overridepublic void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {if (newState == BluetoothProfile.STATE_CONNECTED) {} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {}}@Overridepublic void onServicesDiscovered(BluetoothGatt gatt, int status) {}@Overridepublic void onCharacteristicRead(BluetoothGatt gatt,BluetoothGattCharacteristic characteristic,int status) {}//接收蓝牙回传数据@Overridepublic void onCharacteristicChanged(BluetoothGatt gatt,BluetoothGattCharacteristic characteristic) {System.out.println("接收数据");byte[] data=characteristic.getValue();}//检测用户向蓝牙写数据的状态@Overridepublic void onCharacteristicWrite(BluetoothGatt gatt,BluetoothGattCharacteristic characteristic, int status) {Log.e(TAG, "write status"+":"+status);if(status==BluetoothGatt.GATT_SUCCESS){System.out.println("--------write success----- status:");}super.onCharacteristicWrite(gatt, characteristic, status);}};

       断开连接：

               mBluetoothGatt.disconnect();

 6.发送数据

     //设置特性数据回传通知

  public void setCharacteristicNotification(BluetoothGattCharacteristic characteristic,boolean enabled) {if (mBluetoothAdapter == null || mBluetoothGatt == null) {Log.w(TAG, "BluetoothAdapter not initialized");return;}if (mBluetoothGatt.setCharacteristicNotification(characteristic, enabled)) {BluetoothGattDescriptor descriptor = characteristic.getDescriptor(UUID.fromString("00002902-0000-1000-8000-00805f9b34fb"));descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);mBluetoothGatt.writeDescriptor(descriptor);}}/*** 向设备发送数据* @param serviceUuid* @param characterUuid* @param notifactionUuid* @param data*/public void writeDataToDevice(byte[] data){if (mBluetoothGatt == null) {return;}BluetoothGattService bluetoothGattService = mBluetoothGatt.getService(UUID.fromString("0000fff0-0000-1000-8000-00805f9b34fb"));//蓝牙设备中需要使用的服务的UUIDif (bluetoothGattService == null) {Log.e(TAG, "service:"+mBluetoothGatt.getServices().size());Log.e(TAG, "service not found!");return;}BluetoothGattCharacteristic mCharac = bluetoothGattService.getCharacteristic("0000fff6-0000-1000-8000-00805f9b34fb");//需要使用该服务下具体某个特性的UUIDif (mCharac == null) {Log.e(TAG, "HEART RATE Copntrol Point charateristic not found!");return;}BluetoothGattCharacteristic nCharacteristic=bluetoothGattService.getCharacteristic("0000fff7-0000-1000-8000-00805f9b34fb");//蓝牙模块向手机端回传特性UUIDsetCharacteristicNotification(nCharacteristic, true);Log.e(TAG, "data:"+Arrays.toString(data));mCharac.setValue(data); //设置需要发送的数据try {Thread.sleep(500);} catch (InterruptedException e) {e.printStackTrace();}writeCharacteristic(mCharac);}public void writeCharacteristic(BluetoothGattCharacteristic characteristic) {if (mBluetoothAdapter == null || mBluetoothGatt == null) {Log.e(TAG, "BluetoothAdapter not initialized");return;}boolean result=mBluetoothGatt.writeCharacteristic(characteristic);//开始写入数据if(result){Log.e(TAG, "write success!");}else {Log.e(TAG, "write fail!");}}