Android 蓝牙4.0 BLE 理解

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：

[java] view
plaincopy





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));

}

}

}

}//

}

}