Android 蓝牙4.0 BLE 理解

转载自：http://blog.csdn.net/chaoyue0071/article/details/43450183/
本文简单结合两篇文章
http://blog.csdn.net/hellogv/article/details/24267685
http://blog.csdn.net/jimoduwu/article/details/21604215
在BLE协议中，有两个角色，周边（Periphery）和中央（Central），一个中央可以同时连接多个周边，但是一个周边某一时刻只能连接一个中央。但是不管是Periphery还是Central都是可以实现 GATT server 和 GATT client去传输数据，但是无法同时都是。
大概了解了概念后，看看Android BLE SDK的四个关键类（class）：
a) BluetoothGattServer作为周边来提供数据； BluetoothGattServerCallback返回周边的状态。
b) BluetoothGatt作为中央来使用和处理数据；BluetoothGattCallback返回中央的状态和周边提供的数据。
因为我们讨论的是Android的BLE SDK，下面所有的BluetoothGattServer代表周边，BluetoothGatt代表中央。

一.创建一个周边（虽然目前周边API在Android手机上不工作，但还是看看）
a）先看看周边用到的class，蓝色椭圆

b）说明：
每一个周边BluetoothGattServer，包含多个服务Service，每一个Service包含多个特征Characteristic。
1.new一个特征：character = new BluetoothGattCharacteristic(
UUID.fromString(characteristicUUID),
BluetoothGattCharacteristic.PROPERTY_NOTIFY,
BluetoothGattCharacteristic.PERMISSION_READ);
2.new一个服务：service = new BluetoothGattService(UUID.fromString(serviceUUID),
BluetoothGattService.SERVICE_TYPE_PRIMARY);
3.把特征添加到服务：service.addCharacteristic(character);
4.获取BluetoothManager：manager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
5.获取/打开周边：BluetoothGattServer server = manager.openGattServer(this,
new BluetoothGattServerCallback(){…});
6.把service添加到周边：server.addService(service);
7.开始广播service：Google还没有广播Service的API，等吧！！！！！所以目前我们还不能让一个Android手机作为周边来提供数据。

二.创建一个中央（这次不会让你失望，可以成功创建并且连接到周边的）
a）先看看中央用到的class，蓝色椭圆

b）说明：
为了拿到中央BluetoothGatt，可要爬山涉水十八弯：
1.先拿到BluetoothManager：bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
2.再拿到BluetoothAdapt：btAdapter = bluetoothManager.getAdapter();
3.开始扫描：btAdapter.startLeScan( BluetoothAdapter.LeScanCallback);
4.从LeScanCallback中得到BluetoothDevice：public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {…..}
5.用BluetoothDevice得到BluetoothGatt：gatt = device.connectGatt(this, true, gattCallback);
终于拿到中央BluetoothGatt了，它有一堆方法（查API吧），调用这些方法，你就可以通过BluetoothGattCallback和周边BluetoothGattServer交互了。
官方有给出BLE 通信的sample ，下面是牛人简化了代码，简化得简单明了
本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！
最近穿戴设备发展得很火，把相关技术也带旺了，其中一项是BLE（Bluetooth Low Energy）。BLE是蓝牙4.0的核心Profile，主打功能是快速搜索，快速连接，超低功耗保持连接和传输数据，弱点是数据传输速率低，由于BLE的低功耗特点，因此普遍用于穿戴设备。Android 4.3才开始支持BLE API，所以请各位客官把本文代码运行在蓝牙4.0和Android 4.3及其以上的系统，另外本文所用的BLE终端是一个蓝牙4.0的串口蓝牙模块。
PS：我的i9100刷了4.4系统后，竟然也能跟BLE蓝牙模块通信。

BLE分为三部分Service、Characteristic、Descriptor，这三部分都由UUID作为唯一标示符。一个蓝牙4.0的终端可以包含多个Service，一个Service可以包含多个Characteristic，一个Characteristic包含一个Value和多个Descriptor，一个Descriptor包含一个Value。一般来说，Characteristic是手机与BLE终端交换数据的关键，Characteristic有较多的跟权限相关的字段，例如PERMISSION和PROPERTY，而其中最常用的是PROPERTY，本文所用的BLE蓝牙模块竟然没有标准的Characteristic的PERMISSION。Characteristic的PROPERTY可以通过位运算符组合来设置读写属性，例如READ|WRITE、READ|WRITE_NO_RESPONSE|NOTIFY，因此读取PROPERTY后要分解成所用的组合（本文代码已含此分解方法）。

本文代码改自Android 4.3 Sample的BluetoothLeGatt，把冗余代码去掉，获取的BLE设备信息都通过Log，还有一些必要的读写蓝牙方法，应该算是简化到大家一看就可以懂了。本文代码可以到http://download.csdn.net/detail/hellogv/7228819下载。接下来贴出本文运行的结果，首先是连接BLE设备后，枚举出设备所有Service、Characteristic、Descriptor，并且手机会往Characteristic uuid=0000ffe1-0000-1000-8000-00805f9b34fb写入“send data->”字符串，BLE终端收到数据通过串口传到PC串口助手（见PC串口助手的截图）：
04-21 18:28:25.465: E/DeviceScanActivity(12254): –>service type:PRIMARY

04-21 18:28:25.465: E/DeviceScanActivity(12254): –>includedServices size:0

04-21 18:28:25.465: E/DeviceScanActivity(12254): –>service uuid:00001800-0000-1000-8000-00805f9b34fb

04-21 18:28:25.465: E/DeviceScanActivity(12254): —->char uuid:00002a00-0000-1000-8000-00805f9b34fb

04-21 18:28:25.465: E/DeviceScanActivity(12254): —->char permission:UNKNOW

04-21 18:28:25.465: E/DeviceScanActivity(12254): —->char property:READ

04-21 18:28:25.465: E/DeviceScanActivity(12254): —->char uuid:00002a01-0000-1000-8000-00805f9b34fb

04-21 18:28:25.470: E/DeviceScanActivity(12254): —->char permission:UNKNOW

04-21 18:28:25.470: E/DeviceScanActivity(12254): —->char property:READ

04-21 18:28:25.470: E/DeviceScanActivity(12254): —->char uuid:00002a02-0000-1000-8000-00805f9b34fb

04-21 18:28:25.470: E/DeviceScanActivity(12254): —->char permission:UNKNOW

04-21 18:28:25.470: E/DeviceScanActivity(12254): —->char property:READ|WRITE|

04-21 18:28:25.470: E/DeviceScanActivity(12254): —->char uuid:00002a03-0000-1000-8000-00805f9b34fb

04-21 18:28:25.470: E/DeviceScanActivity(12254): —->char permission:UNKNOW

04-21 18:28:25.475: E/DeviceScanActivity(12254): —->char property:READ|WRITE|

04-21 18:28:25.475: E/DeviceScanActivity(12254): —->char uuid:00002a04-0000-1000-8000-00805f9b34fb

04-21 18:28:25.475: E/DeviceScanActivity(12254): —->char permission:UNKNOW

04-21 18:28:25.475: E/DeviceScanActivity(12254): —->char property:READ

04-21 18:28:25.475: E/DeviceScanActivity(12254): –>service type:PRIMARY

04-21 18:28:25.475: E/DeviceScanActivity(12254): –>includedServices size:0

04-21 18:28:25.475: E/DeviceScanActivity(12254): –>service uuid:00001801-0000-1000-8000-00805f9b34fb

04-21 18:28:25.480: E/DeviceScanActivity(12254): —->char uuid:00002a05-0000-1000-8000-00805f9b34fb

04-21 18:28:25.480: E/DeviceScanActivity(12254): —->char permission:UNKNOW

04-21 18:28:25.480: E/DeviceScanActivity(12254): —->char property:INDICATE

04-21 18:28:25.480: E/DeviceScanActivity(12254): ——–>desc uuid:00002902-0000-1000-8000-00805f9b34fb

04-21 18:28:25.480: E/DeviceScanActivity(12254): ——–>desc permission:UNKNOW

04-21 18:28:25.480: E/DeviceScanActivity(12254): –>service type:PRIMARY

04-21 18:28:25.480: E/DeviceScanActivity(12254): –>includedServices size:0

04-21 18:28:25.480: E/DeviceScanActivity(12254): –>service uuid:0000ffe0-0000-1000-8000-00805f9b34fb

04-21 18:28:25.480: E/DeviceScanActivity(12254): —->char uuid:0000ffe1-0000-1000-8000-00805f9b34fb

04-21 18:28:25.480: E/DeviceScanActivity(12254): —->char permission:UNKNOW

04-21 18:28:25.480: E/DeviceScanActivity(12254): —->char property:READ|WRITE_NO_RESPONSE|NOTIFY|

04-21 18:28:25.490: E/DeviceScanActivity(12254): ——–>desc uuid:00002902-0000-1000-8000-00805f9b34fb

04-21 18:28:25.490: E/DeviceScanActivity(12254): ——–>desc permission:UNKNOW

04-21 18:28:25.490: E/DeviceScanActivity(12254): ——–>desc uuid:00002901-0000-1000-8000-00805f9b34fb

04-21 18:28:25.490: E/DeviceScanActivity(12254): ——–>desc permission:UNKNOW

04-21 18:28:26.025: E/DeviceScanActivity(12254): onCharRead BLE DEVICE read 0000ffe1-0000-1000-8000-00805f9b34fb -> 00
这里红字是由BluetoothGattCallback的onCharacteristicRead()回调而打出Log

以下Log是PC上的串口工具通过BLE模块发送过来，由BluetoothGattCallback的 onCharacteristicChanged（）打出Log

04-21 18:30:18.260: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:18.745: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:19.085: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:19.350: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:19.605: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:19.835: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:20.055: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:20.320: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:20.510: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:20.735: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

04-21 18:30:21.000: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone

接下来贴出本文核心代码：

public class DeviceScanActivity extends ListActivity {      private final static String TAG = DeviceScanActivity.class.getSimpleName();      private final static String UUID_KEY_DATA = "0000ffe1-0000-1000-8000-00805f9b34fb";      private LeDeviceListAdapter mLeDeviceListAdapter;      /**搜索BLE终端*/      private BluetoothAdapter mBluetoothAdapter;      /**读写BLE终端*/      private BluetoothLeClass mBLE;      private boolean mScanning;      private Handler mHandler;      // Stops scanning after 10 seconds.      private static final long SCAN_PERIOD = 10000;      @Override      public void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          getActionBar().setTitle(R.string.title_devices);          mHandler = new Handler();          // Use this check to determine whether BLE is supported on the device.  Then you can          // selectively disable BLE-related features.          if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {              Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();              finish();          }          // Initializes a Bluetooth adapter.  For API level 18 and above, get a reference to          // BluetoothAdapter through BluetoothManager.          final BluetoothManager bluetoothManager =                  (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);          mBluetoothAdapter = bluetoothManager.getAdapter();          // Checks if Bluetooth is supported on the device.          if (mBluetoothAdapter == null) {              Toast.makeText(this, R.string.error_bluetooth_not_supported, Toast.LENGTH_SHORT).show();              finish();              return;          }          //开启蓝牙          mBluetoothAdapter.enable();          mBLE = new BluetoothLeClass(this);          if (!mBLE.initialize()) {              Log.e(TAG, "Unable to initialize Bluetooth");              finish();          }          //发现BLE终端的Service时回调          mBLE.setOnServiceDiscoverListener(mOnServiceDiscover);          //收到BLE终端数据交互的事件          mBLE.setOnDataAvailableListener(mOnDataAvailable);      }      @Override      protected void onResume() {          super.onResume();          // Initializes list view adapter.          mLeDeviceListAdapter = new LeDeviceListAdapter(this);          setListAdapter(mLeDeviceListAdapter);          scanLeDevice(true);      }      @Override      protected void onPause() {          super.onPause();          scanLeDevice(false);          mLeDeviceListAdapter.clear();          mBLE.disconnect();      }      @Override      protected void onStop() {          super.onStop();          mBLE.close();      }      @Override      protected void onListItemClick(ListView l, View v, int position, long id) {          final BluetoothDevice device = mLeDeviceListAdapter.getDevice(position);          if (device == null) return;          if (mScanning) {              mBluetoothAdapter.stopLeScan(mLeScanCallback);              mScanning = false;          }          mBLE.connect(device.getAddress());      }      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);                      invalidateOptionsMenu();                  }              }, SCAN_PERIOD);              mScanning = true;              mBluetoothAdapter.startLeScan(mLeScanCallback);          } else {              mScanning = false;              mBluetoothAdapter.stopLeScan(mLeScanCallback);          }          invalidateOptionsMenu();      }      /**      * 搜索到BLE终端服务的事件      */      private BluetoothLeClass.OnServiceDiscoverListener mOnServiceDiscover = new OnServiceDiscoverListener(){          @Override          public void onServiceDiscover(BluetoothGatt gatt) {              displayGattServices(mBLE.getSupportedGattServices());          }      };      /**      * 收到BLE终端数据交互的事件      */      private BluetoothLeClass.OnDataAvailableListener mOnDataAvailable = new OnDataAvailableListener(){          /**          * BLE终端数据被读的事件          */          @Override          public void onCharacteristicRead(BluetoothGatt gatt,                  BluetoothGattCharacteristic characteristic, int status) {              if (status == BluetoothGatt.GATT_SUCCESS)                   Log.e(TAG,"onCharRead "+gatt.getDevice().getName()                          +" read "                          +characteristic.getUuid().toString()                          +" -> "                          +Utils.bytesToHexString(characteristic.getValue()));          }          /**          * 收到BLE终端写入数据回调          */          @Override          public void onCharacteristicWrite(BluetoothGatt gatt,                  BluetoothGattCharacteristic characteristic) {              Log.e(TAG,"onCharWrite "+gatt.getDevice().getName()                      +" write "                      +characteristic.getUuid().toString()                      +" -> "                      +new String(characteristic.getValue()));          }      };      // Device scan callback.      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() {                      mLeDeviceListAdapter.addDevice(device);                      mLeDeviceListAdapter.notifyDataSetChanged();                  }              });          }      };      private void displayGattServices(List<BluetoothGattService> gattServices) {          if (gattServices == null) return;          for (BluetoothGattService gattService : gattServices) {              //-----Service的字段信息-----//              int type = gattService.getType();              Log.e(TAG,"-->service type:"+Utils.getServiceType(type));              Log.e(TAG,"-->includedServices size:"+gattService.getIncludedServices().size());              Log.e(TAG,"-->service uuid:"+gattService.getUuid());              //-----Characteristics的字段信息-----//              List<BluetoothGattCharacteristic> gattCharacteristics =gattService.getCharacteristics();              for (final BluetoothGattCharacteristic  gattCharacteristic: gattCharacteristics) {                  Log.e(TAG,"---->char uuid:"+gattCharacteristic.getUuid());                  int permission = gattCharacteristic.getPermissions();                  Log.e(TAG,"---->char permission:"+Utils.getCharPermission(permission));                  int property = gattCharacteristic.getProperties();                  Log.e(TAG,"---->char property:"+Utils.getCharPropertie(property));                  byte[] data = gattCharacteristic.getValue();                  if (data != null && data.length > 0) {                      Log.e(TAG,"---->char value:"+new String(data));                  }                  //UUID_KEY_DATA是可以跟蓝牙模块串口通信的Characteristic                  if(gattCharacteristic.getUuid().toString().equals(UUID_KEY_DATA)){                                        //测试读取当前Characteristic数据，会触发mOnDataAvailable.onCharacteristicRead()                      mHandler.postDelayed(new Runnable() {                          @Override                          public void run() {                              mBLE.readCharacteristic(gattCharacteristic);                          }                      }, 500);                      //接受Characteristic被写的通知,收到蓝牙模块的数据后会触发mOnDataAvailable.onCharacteristicWrite()                      mBLE.setCharacteristicNotification(gattCharacteristic, true);                      //设置数据内容                      gattCharacteristic.setValue("send data->");                      //往蓝牙模块写入数据                      mBLE.writeCharacteristic(gattCharacteristic);                  }                  //-----Descriptors的字段信息-----//                  List<BluetoothGattDescriptor> gattDescriptors = gattCharacteristic.getDescriptors();                  for (BluetoothGattDescriptor gattDescriptor : gattDescriptors) {                      Log.e(TAG, "-------->desc uuid:" + gattDescriptor.getUuid());                      int descPermission = gattDescriptor.getPermissions();                      Log.e(TAG,"-------->desc permission:"+ Utils.getDescPermission(descPermission));                      byte[] desData = gattDescriptor.getValue();                      if (desData != null && desData.length > 0) {                          Log.e(TAG, "-------->desc value:"+ new String(desData));                      }                   }              }          }//      }  }