Android BLE中Peripheral端和客户端
角色和职责
-
Android设备与BLE设备交互有两组角色：
中心设备和外围设备（Central vs. peripheral）； GATT server vs. GATT client.
-
Central vs. peripheral:
中心设备和外围设备的概念针对的是BLE连接本身。Central角色负责scan advertisement。而peripheral角色负责make advertisement。
这两种角色取决于BLE连接成功后，两个设备间通信的方式。
举例说明： 现有一个活动追踪的BLE设备和一个支持BLE的Android设备。Android设备支持Central角色，而BLE设备支持peripheral角色。创建一个BLE连接需要这两个角色都存在，都仅支持Central角色或者都仅支持peripheral角色则无法建立连接。
当连接建立后，它们之间就需要传输GATT数据。谁做server，谁做client，则取决于具体数据传输的情况。例如，如果活动追踪的BLE设备需要向 Android设备传输sensor数据，则活动追踪器自然成为了server端；而如果活动追踪器需要从Android设备获取更新信息，则 Android设备作为server端可能更合适。
首先说明一点，并不是Android L的系统就可以支持BLE Peripheral，这个和硬件也是有关系的（以前有人告诉我支持BLE Peripheral是纯软件的东西，要不就是扯淡，要不就是我测得有问题）。我用我手上的Pad（支持BLE central，android5.0）发现直接不支持，Android5.0 SDK已经开始支持check手机是否支持BLE Peripheral。
检查是否支持BLE、BLE Peripheral。代码如下
private void init(){
if(!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)){
Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_LONG).show();
finish();
}
final BluetoothManager mBluetoothManager = (BluetoothManager) getSystemService(BLUETOOTH_SERVICE);
mBluetoothAdapter = mBluetoothManager.getAdapter();
if(mBluetoothAdapter == null){
Toast.makeText(this, R.string.bluetooth_not_supported, Toast.LENGTH_LONG).show();
finish();
}
mBluetoothLeAdvertiser = mBluetoothAdapter.getBluetoothLeAdvertiser();
if(mBluetoothLeAdvertiser == null){
Toast.makeText(this, "the device not support peripheral", Toast.LENGTH_SHORT).show();
Log.e(TAG, "the device not support peripheral");
finish();
}
}
关键代码：
mBluetoothLeAdvertiser = mBluetoothAdapter.getBluetoothLeAdvertiser();
这一句代码会直接判断你的设备到底支持不支持BLE Peripheral。假如此返回值非空，你才可以继续有机会开发，如果返回空，那说明你的设备搞不了BLE Peripheral。
支持不支持BLE Peripheral，你也可以用BluetoothAdapter类的isMultipleAdvertisementSupported()函数去check，实际上getBluetoothLeAdvetiser（）也会执行上面的isMultipleAdvertisementSupported函数
Peripheral端
- 设置蓝牙权限
<uses-permission android:name="android.permission.BLUETOOTH" /> <uses-permission android :name="android.permission.BLUETOOTH_ADMIN" /> - 打开蓝牙
mBluetoothManager = (BluetoothManager) getSystemService(Context. BLUETOOTH_SERVICE); mBluetoothAdapter = mBluetoothManager.getAdapter(); if (mBluetoothAdapter == null) { Toast.makeText( this, "手机不支持peripheral", Toast. LENGTH_LONG).show(); Log. e(TAG, "Bluetooth not supported" ); finish() ; } else if (! mBluetoothAdapter.isEnabled()) { // Make sure bluetooth is enabled. /*Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);*/ mBluetoothAdapter .enable();//强制打开蓝牙 } - 打开服务（使客户端能够发现该外围设备）
3.1. 设置外围设备配置
mAdvertiseSettings = new AdvertiseSettings.Builder() .setAdvertiseMode(AdvertiseSettings.ADVERTISE_MODE_BALANCED) .setTxPowerLevel(AdvertiseSettings.ADVERTISE_TX_POWER_MEDIUM) .setConnectable(true ) .build();3.2. 设置外围设备显示数据mAdvData = new AdvertiseData.Builder() .setIncludeDeviceName(true) .setIncludeTxPowerLevel(true) .addServiceUuid(new ParcelUuid(UUID_SERVICE)) .build();3.3. 开启外围服务mBluetoothLeAdvertiser = mBluetoothAdapter.getBluetoothLeAdvertiser(); mBluetoothLeAdvertiser.startAdvertising(mAdvertiseSettings, mAdvData, mAdvertiseCallback); mGattServer = mBluetoothManager.openGattServer(this, mBluetoothGattServerCallback); - 给外围设备添加Server和Characteristic
BluetoothGattService service = new BluetoothGattService(UUID_SERVICE,BluetoothGattService. SERVICE_TYPE_PRIMARY); BluetoothGattCharacteristic characteristic = new BluetoothGattCharacteristic(UUID_Characteristic,BluetoothGattCharacteristic. PROPERTY_READ|BluetoothGattCharacteristic.PROPERTY_WRITE, BluetoothGattCharacteristic. PERMISSION_READ|BluetoothGattCharacteristic.PERMISSION_WRITE) ; service.addCharacteristic(characteristic) ; final boolean b = mGattServer.addService(service); - Characteristic的值改变时通知客户端
final BluetoothGattService service = mGattServer.getService(UUID_SERVICE ); final BluetoothGattCharacteristic characteristic = service.getCharacteristic( UUID_Characteristic); String str = editText.getText().toString(); Log.i(TAG, str.length()+""); characteristic.setValue(str); boolean b = mGattServer.notifyCharacteristicChanged(romoteDevice, characteristic,true) ; - 实现BluetoothGattServerCallback
6.1. 在客户端readCharacteristic时会触发
onCharacteristicReadRequest事件，调用mGattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS,offset, characteristic.getValue());来通知客户端的回调 6.2. 在客户端writeCharacteristic时会触发
onCharacteristicWriteRequest事件，调用mGattServer .sendResponse来通知客户端回调
- 关闭peripheral
mBluetoothLeAdvertiser.stopAdvertising(mAdvertiseCallback);
BLE客户端
- 设置权限和打开蓝牙和peripheral端一样设置
- 搜索BLE设备
mAdapter .startLeScan(leScanCallback) ; LeScanCallback leScanCallback = new LeScanCallback() { @Override public void onLeScan (final BluetoothDevice bluetoothdevice , int i, byte [] abyte0) { runOnUiThread( new Runnable() { @Override public void run() { findDevice( bluetoothdevice); } }) ; } }; - 关闭搜索
mAdapter.stopLeScan(leScanCallback); - 连接BLE设备
BluetoothGatt connectGatt = remoteDevice.connectGatt(this, false, mBluetoothGattCallback); - 向peripheral端写入数据
final BluetoothGattService service = connectGatt.getService(UUID_SERVICE ); final BluetoothGattCharacteristic characteristic = service.getCharacteristic( UUID_Characteristic); int property = characteristic.getProperties() ; Log.e(TAG, "---->char property:" +Utils.getCharPropertie(property)); connectGatt .setCharacteristicNotification(characteristic , true); String str = editText.getText().toString(); Log. i(TAG, str.length()+"") ; characteristic.setValue(str) ; boolean b = connectGatt.writeCharacteristic(characteristic); - 读取peripheral端的数据
final BluetoothGattService service = connectGatt.getService(UUID_SERVICE); final BluetoothGattCharacteristic characteristic = service.getCharacteristic( UUID_Characteristic); byte[] value = characteristic.getValue(); boolean b= connectGatt.readCharacteristic(characteristic);
学习资料：https://github.com/WebBluetoothCG/ble-test-peripheral-android https://github.com/suzp1984/Light_BLE https://github.com/Sensirion/libble-android
注：peripheral只能20个字节 client超过20个字节就只能发送18个字节