Android BLE低功耗蓝牙开发
2016-11-11 本文已影响2325人
Yestin
最近做了一个智能硬件开发（针灸仪）的项目，有一部分涉及到低功耗蓝牙的开发，就是通过蓝牙和设备进行数据的交互，比如控制改设备的LED的开关，设备的开关机，设置设备的时间和温度等，下面就项目中遇到的坑一一说明：首先给出官网对于BLE开发的讲解,https://developer.Android.com/guide/topics/connectivity/bluetooth-le.html#terms官方demo：https://github.com/googlesamples/android-BluetoothLeGatt，demo也比较好理解，主要是四个类，其中，DeviceControlActivity通过启动BluetoothLeService用来进行与蓝牙外围设备的交互。（注意，因为本人是将UI做了更改，并放到了fragment中，所以部分代码跟demo不一致，请主动忽略，关注蓝牙核心代码）
BLE开发所需要的知识，通过官方demo，我们会发现很多service，点击service后，每个service下面是Characteristic，每个service和Characteristic都对应一个唯一的UUID。所以，在做BLE时候，首先你应该找出你的蓝牙外围设备uuid，不然会很头疼，这个UUID也可能是硬件给你的，也可以你自己试出来，当然自己试出来是个很烦的过程。自己试的方法就是根据demo，加上一份读写的协议，然后，排着点击，显示出来的蓝牙列表进行测试，看是否和协议对应。另外，BluetoothLeService类不用做太多的更改。
一，蓝牙设备的扫描
这一部分基本上很简单，只要设备上电以后，这部分代码执行后，便可以扫描出设备，并获得BluetoothDevice对象
public void scanLeDevice(final boolean enable) {
LogUtils.debug(TAG, "-----------开始扫描蓝牙=" + enable);
if (enable) {
// Stops scanning after a pre-defined scan period.
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
stopScanOuter();
}
}, SCAN_PERIOD);
LogUtils.debug("----------startLeScan--");
mScanning = true;
mBluetoothAdapter.startLeScan(this);
} else {
mScanning = false;
mBluetoothAdapter.stopLeScan(this);
}
}
上面代码为开始扫描周围已上电的设备，当发现设备后，BluetoothAdapter.LeScanCallback会执行onLeScan回调，将BluetoothDevice返回，
@Override
public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {
Fragment dcfrag = getActivity().getSupportFragmentManager().findFragmentByTag("MyDeviceFragment");
if(dcfrag != null && dcfrag.isVisible()) {
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
LogUtils.debug(TAG, "---------获得设备" + device);
mLeDeviceListAdapter.addDevice(device);
mLeDeviceListAdapter.notifyDataSetChanged();
}
});
}
}
到此，我们便可以得到扫描到的蓝牙设备，但是目前仅仅是扫描到，并不代表已经连接上蓝牙设备。
二，蓝牙设备的连接
1，绑定service
private final ServiceConnection mServiceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder service) {
LogUtils.debug(TAG, "开始绑定service onServiceConnected"+device+"---name="+device.getName()+"--address="+device.getAddress());
mDeviceAddress = device.getAddress();
mDeviceName = device.getName();
mBluetoothLeService = ((BluetoothLeService.LocalBinder) service).getService();
if (!mBluetoothLeService.initialize()) {
Log.i(TAG, "Unable to initialize Bluetooth");
}
// Automatically connects to the device upon successful start-up initialization.
mBluetoothLeService.connect(mDeviceAddress);
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
LogUtils.debug(TAG, "--------onServiceDisconnected service无法绑定了");
mBluetoothLeService = null;
}
};
public void mybindService(){
LogUtils.debug(TAG, "---------开始执行onCreate---bindservice");
Intent gattServiceIntent = new Intent(getActivity(), BluetoothLeService.class);
getActivity().bindService(gattServiceIntent, mServiceConnection, getActivity().BIND_AUTO_CREATE);
}
2，连接蓝牙
private final BroadcastReceiver mGattUpdateReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (BluetoothLeService.ACTION_GATT_CONNECTED.equals(action)) {
LogUtils.debug(TAG, "--mGattUpdateReceiver ACTION_GATT_CONNECTED");
mConnected = true;
LogUtils.debug(TAG, "--------ACTION_GATT_CONNECTED devicename"+mDeviceName);
Fragment dcfrag = getActivity().getSupportFragmentManager().findFragmentByTag("ConnectFragment");
if((dcfrag != null && dcfrag.isVisible())){
//暂时写死在这可以连接的BLE设备
if(mDeviceName == null || !deviceFilter(mDeviceName)){
connectService.switchFragment(false, mDeviceName);
}else{
connectService.switchFragment(true, mDeviceName);
}
}
} else if (BluetoothLeService.ACTION_GATT_DISCONNECTED.equals(action)) {
LogUtils.debug(TAG, "--mGattUpdateReceiver ACTION_GATT_DISCONNECTED");
mConnected = false;
Fragment dcfrag = getActivity().getSupportFragmentManager().findFragmentByTag("ConnectFragment");
if((dcfrag != null && dcfrag.isVisible()))
connectService.switchFragment(false, mDeviceName);
Fragment contfrag = getActivity().getSupportFragmentManager().findFragmentByTag("ControlorFragment");
if((contfrag != null && contfrag.isVisible())){
transfertoControler.closeButton(false, false);
}
} else if (BluetoothLeService.ACTION_GATT_SERVICES_DISCOVERED.equals(action)) {
LogUtils.debug(TAG, "--mGattUpdateReceiver ACTION_GATT_SERVICES_DISCOVERED");
initMoxibustionService(
mBluetoothLeService.getSupportedGatteService(
SampleGattAttributes.SERVIECE_NOTIFY_DATA));
initMoxibustionService(
mBluetoothLeService.getSupportedGatteService(
SampleGattAttributes.SERVIECE_WRITE_DATA));
// Show all the supported services and characteristics on the user interface.
// displayGattServices(mBluetoothLeService.getSupportedGattServices());
} else if (BluetoothLeService.ACTION_DATA_AVAILABLE.equals(action)) {
LogUtils.debug(TAG, "--mGattUpdateReceiver ACTION_DATA_AVAILABLE");
// byte[] data = intent.getByteArrayExtra(BluetoothLeService.EXTRA_DATA);
// StringBuilder stringBuilder = new StringBuilder(data.length);
// for(byte byteChar : data)
// stringBuilder.append(String.format("0x%02X ", byteChar));
// String log = stringBuilder.toString();
// LogUtils.debug(TAG, "---字节数组为="+ log);
parsedata(intent.getByteArrayExtra(BluetoothLeService.EXTRA_DATA));
} else if (BluetoothLeService.ACTION_DATA_SEND_CONFIRM.equals(action)) {
// ECHO from android
LogUtils.debug(TAG, "write ok!");
}
}
};
public void myConnetService(){
getActivity().registerReceiver(mGattUpdateReceiver, makeGattUpdateIntentFilter());
LogUtils.debug(TAG, "------mBluetoothLeService myConnetService" + mBluetoothLeService);
if (mBluetoothLeService != null) {
final boolean result = mBluetoothLeService.connect(mDeviceAddress);
LogUtils.debug(TAG, "Connect request result=" + result);
}
}
当连接上蓝牙后，我们会得到ACTION_GATT_CONNECTED的广播，然后是ACTION_GATT_SERVICES_DISCOVERED，这个时候我们需要对service进行初始化，以便能够读写数据，以下为初始化代码（注意，初始化时候我们需要用到读写service的UUID）
private void initMoxibustionService(BluetoothGattService gattService) {
String uuid = "";
if (gattService == null)
{
LogUtils.debug(TAG, "gattService is null");
return;
}
List<BluetoothGattCharacteristic> gattCharacteristics = gattService.getCharacteristics();
for (BluetoothGattCharacteristic gattCharacteristic : gattCharacteristics) {
uuid = gattCharacteristic.getUuid().toString();
if (SampleGattAttributes.CHARACTER_NOTIFY_DATA.substring(0,8).equals(uuid.substring(0, 8))) {
mNotifyCharacteristic = gattCharacteristic;
mBluetoothLeService.setCharacteristicNotification(
mNotifyCharacteristic, true);
LogUtils.debug(TAG, "NOTIFY_DATA");
LogUtils.debug(TAG, "getProperties()=" + mNotifyCharacteristic.getProperties());
} else if (SampleGattAttributes.CHARACTER_WRITE_DATA.substring(0,8).equals(uuid.subSequence(0, 8))) {
// mCommandCharacteristic = gattCharacteristic;
//写数据的服务和characteristic
mCommandCharacteristic = mBluetoothLeService.getSupportedGatteService(SampleGattAttributes.SERVIECE_WRITE_DATA)
.getCharacteristic(UUID.fromString(SampleGattAttributes.CHARACTER_WRITE_DATA));
LogUtils.debug(TAG, "WRITE_CMD");
LogUtils.debug(TAG, "getProperties()=" + mCommandCharacteristic.getProperties());
mCommandCharacteristic.setWriteType(
BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT);
LogUtils.debug(TAG, "getProperties()=" + mCommandCharacteristic.getProperties());
}
}
}
CHARACTER_NOTIFY_DATA和CHARACTER_WRITE_DATA为读和写数据的CHARACTER的UUID，如下，注意这四个UUID
3，解析数据
至此，如果顺利的话，我们就可以得到ACTION_DATA_AVAILABLE的广播，也就拿到了从蓝牙设备获得的byte数组，大多数协议里，每个字节代表一个命令。这里涉及到Java中byte值与int值的转换。因为Java中，所有的值都是singed性的，最高位为符号位，所以，大家请自行补下该部分的知识，对于有符号数，它的值相当于取补码，此处将不详述，
上面为读数据，下面我们说写数据，比如，如下的开关机命令，
// 01 10 01 01 92 07 17
public void controlpower(boolean isOpen){
if (mCommandCharacteristic == null) return;
if (mBluetoothLeService == null) return;
byte[] setDataAfter;
if(isOpen){
byte[] setDataBefore = {0x01, 0x10, 0x01, 0x01};
byte[] trans = inttobyte(integrityCheck(setDataBefore));
byte[] transV = Arrays.copyOfRange(trans, 2, 4);
byte[] setData = byteMerger(setDataBefore, reverse(transV));
byte[] dd = {0x17};
setDataAfter = byteMerger(setData, dd);
LogUtils.debug(TAG, "---setDataAfter[4]="+setDataAfter[4]+",setDataAfter[5]="+setDataAfter[5]);
}else{
byte[] setDataBefore = {0x01, 0x10, 0x01, 0x00};
byte[] trans = inttobyte(integrityCheck(setDataBefore));
byte[] transV = Arrays.copyOfRange(trans, 2, 4);
byte[] setData = byteMerger(setDataBefore, reverse(transV));
byte[] dd = {0x17};
setDataAfter = byteMerger(setData, dd);
printDataHex(setDataAfter);
}
mCommandCharacteristic.setValue(setDataAfter);
mBluetoothLeService.writeCharacteristic(mCommandCharacteristic);
}
mCommandCharacteristic.setValue(setDataAfter);
mBluetoothLeService.writeCharacteristic(mCommandCharacteristic);
这两行代码，是核心代码，但是，我们要进行字节数组的正确传递，这里，给大家贴出来几个很有可能用到的方法，
CRC算法Java版：
//crc java
public int integrityCheck(byte[] bytes) {
int wCrc = 0xffff;
for (byte srcData : bytes) {
int data = byteToInt(srcData);
for(int j = 0; j < 8; j++) {
if ((((wCrc & 0x8000) >> 8) ^ ((data << j) & 0x80)) != 0) {
wCrc = (wCrc << 1) ^ 0x1021;
} else {
wCrc = wCrc << 1;
}
}
}
wCrc = (wCrc << 8) | (wCrc >> 8 & 0xff);
return wCrc & 0xffff;
}
public static int byteToInt(byte b) {
return b & 0xff;
}
// int to byte
public static byte[] inttobyte(int value) {
byte b0 = (byte) ((value >> 24) & 0xFF);
byte b1 = (byte) ((value >> 16) & 0xFF);
byte b2 = (byte) ((value >> 8) & 0xFF);
byte b3 = (byte) (value & 0xFF);
byte[] bytes = { b0, b1, b2, b3 };
return bytes;
}
//打印字节数组
public void printDataHex(byte[] data) {
if(SENTLOG){
StringBuilder stringBuilder = new StringBuilder(data.length);
for(byte byteChar : data)
stringBuilder.append(String.format("0x%02X ", byteChar));
String log = stringBuilder.toString();
LogUtils.debug(TAG, "---发送到蓝牙的字节数组为="+ log);
}
}
//数组倒序
public byte[] reverse(byte[] rt){
for (int i = 0; i < rt.length / 2; i++) {
byte temp = rt[i];
rt[i] = rt[rt.length - 1 - i];
rt[rt.length - 1 - i] = temp;
}
return rt;
}
//java 合并两个byte数组
public static byte[] byteMerger(byte[] byte_1, byte[] byte_2){
byte[] byte_3 = new byte[byte_1.length+byte_2.length];
System.arraycopy(byte_1, 0, byte_3, 0, byte_1.length);
System.arraycopy(byte_2, 0, byte_3, byte_1.length, byte_2.length);
return byte_3;
}
写的比较简单，但是关键代码都有了，大家可以参考下！~
