蓝牙（ Bluetooth? ）：是一种无线技术标准，可实现固定设备、移动设备和楼宇个人域网之间的短距离数据交换（使用2.4—2.485GHz的ISM波段的UHF无线电波）。蓝牙技术最初由电信巨头爱立信公司于1994年创制，当时是作为RS232数据线的替代方案。蓝牙可连接多个设备，克服了数据同步的难题。
如今蓝牙由蓝牙技术联盟（Bluetooth Special Interest Group，简称SIG）管理。蓝牙技术联盟在全球拥有超过25,000家成员公司，它们分布在电信、计算机、网络、和消费电子等多重领域。IEEE将蓝牙技术列为IEEE 802.15.1，但如今已不再维持该标准。蓝牙技术联盟负责监督蓝牙规范的开发，管理认证项目，并维护商标权益。制造商的设备必须符合蓝牙技术联盟的标准才能以“蓝牙设备”的名义进入市场。蓝牙技术拥有一套专利网络，可发放给符合标准的设备。
一、蓝牙的分类
目前为止蓝牙分为两类：一是经典蓝牙（传统蓝牙），二是低功耗蓝牙（BLE）。顾名思义低功耗蓝牙功耗要比传统蓝牙低，所以广泛使用在智能穿戴设备上。要使安卓设备连接上智能穿戴设备（如智能手表），通过经典蓝牙的socket连接一般是连接不上的（为什么说一般呢，因为有些不良厂家和杂牌智能手环用的不是低功耗蓝牙，这个可以使用经典蓝牙连接上），必须要使用BLE的 GATT连接才能连接上。
二、GATT中的服务、特征值、描述、UUID
GATT连接涉及到四个比较陌生的名词：服务（service）、特征值（Characteristic）、描述（discript）、UUID，下面以智能手环为例分别来解释一下这些名词是什么意思。
- service：服务是包含了若干个数据包（特征值）的集合，一个智能设备可能包含多个服务，使用之恩那个设备生产厂商提供的UUID码来识别。比如之恩那个手环中有测心率的服务、步数的服务，心率和步数的数据包（特征值）都包含在服务中，通过指定的UUID来辨别到底是心率的服务还是步数的服务。
- characteristic：特征值包含在服务里面，顾名思义就是一种数据值，特征值包含一个或者多个描述。如心率是多少，今天走了多少步都可以放进特征值里面，服务中有多个特征值，也是通过UUID来识别
- discript：描述一般是对特征值的值进行描述，比如单位等等的描述，开发中一般用不到（我用不到）
- UUID：由蓝牙设备厂商提供的UUID，UUID是在硬件编程里已经确定了的，想要草所特定的服务、特征值都需要通过UUID来找。
三、安卓中GATT的操作
和经典蓝牙最开始一样，要检测蓝牙是否可用和蓝牙是否打开，这部分代码就不贴出来了。
一般操作GATT的教程都把操作放在安卓的server里面，具体原因还请大神指教。下面的server代码可以直接当作操作GATT的模板来使用，大部分都是些回调函数和对服务、特征值进行操作的方法：
public class UartService extends Service {
private final static String TAG = UartService.class.getSimpleName();
List<BluetoothGattService> serviceList = new ArrayList<BluetoothGattService>();//发现的服务列表
private BluetoothAdapter mBluetoothAdapter;//本地蓝牙适配器
private String mBluetoothDeviceAddress;//本地蓝牙MAC地址
private BluetoothGatt mBluetoothGatt;//GTAA
/**
* 假设生产商提供了一个服务，该服务里面有两个特征值
*/
private BluetoothGattService mBluetoothGattService;//gatt服务
private BluetoothGattCharacteristic mBluetoothGattCharacteristic1;//gatt特征值1
private BluetoothGattCharacteristic mBluetoothGattCharacteristic2;//gatt特征值2
private int mConnectionState = STATE_DISCONNECTED;
//连接状态常量
private static final int STATE_DISCONNECTED = 0;
private static final int STATE_CONNECTING = 1;
private static final int STATE_CONNECTED = 2;
//蓝牙厂商提供的UUID
private static final UUID UUID_SERVICE = UUID.fromString("0000fff0-0000-1000-8000-00805f9b34fb"); //服务
private static final UUID UUID_CHARA1 = UUID.fromString("0000fff1-0000-1000-8000-00805f9b34fb"); //特征值1
private static final UUID UUID_CHARA2 = UUID.fromString("0000fff4-0000-1000-8000-00805f9b34fb"); //特征值2
// Implements callback methods for GATT events that the app cares about. For example,
// connection change and services discovered.
private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
if (newState == BluetoothProfile.STATE_CONNECTED) {
mConnectionState = STATE_CONNECTED;
Log.i(TAG, "Connected to GATT server.");
// Attempts to discover services after successful connection.
Log.i(TAG, "Attempting to start service discovery:" +
mBluetoothGatt.discoverServices());
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
mConnectionState = STATE_DISCONNECTED;
Log.i(TAG, "Disconnected from GATT server.");
}
}
@Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {//服务被发现
if (status == BluetoothGatt.GATT_SUCCESS) {
System.out.println("Service has bean discover.");
mBluetoothGattService = gatt.getService(UUID_SERVICE);//发现服务
} else {
Log.w(TAG, "onServicesDiscovered received: " + status);
}
}
@Override
public void onCharacteristicRead(BluetoothGatt gatt,
BluetoothGattCharacteristic characteristic,
int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
Utiles.setData(characteristic);
}
}
@Override
public void onCharacteristicWrite(BluetoothGatt gatt,
BluetoothGattCharacteristic characteristic,
int status) {
}
@Override
public void onCharacteristicChanged(BluetoothGatt gatt,
BluetoothGattCharacteristic characteristic) {
}
};
public class LocalBinder extends Binder {
UartService getService() {
return UartService.this;
}
}
@Override
public IBinder onBind(Intent intent) {
return mBinder;
}
@Override
public boolean onUnbind(Intent intent) {
// After using a given device, you should make sure that BluetoothGatt.close() is called
// such that resources are cleaned up properly. In this particular example, close() is
// invoked when the UI is disconnected from the Service.
close();
return super.onUnbind(intent);
}
private final IBinder mBinder = new LocalBinder();
/**
* Initializes a reference to the local Bluetooth adapter.
*
* @return Return true if the initialization is successful.
*/
public boolean initialize() {//初始化
// For API level 18 and above, get a reference to BluetoothAdapter through
// BluetoothManager.
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
Log.e(TAG, "Unable to obtain a BluetoothAdapter.");
return false;
}
return true;
}
/**
* Connects to the GATT server hosted on the Bluetooth LE device.
*
* @param address The device address of the destination device.
*
* @return Return true if the connection is initiated successfully. The connection result
* is reported asynchronously through the
* {@code BluetoothGattCallback#onConnectionStateChange(android.bluetooth.BluetoothGatt, int, int)}
* callback.
*/
public boolean connect(final String address) {//连接服务
if (mBluetoothAdapter == null || address == null) {
Log.w(TAG, "BluetoothAdapter not initialized or unspecified address.");
return false;
}
// Previously connected device. Try to reconnect.
if (mBluetoothDeviceAddress != null && address.equals(mBluetoothDeviceAddress)
&& mBluetoothGatt != null) {
Log.d(TAG, "Trying to use an existing mBluetoothGatt for connection.");
if (mBluetoothGatt.connect()) {
mConnectionState = STATE_CONNECTING;
return true;
} else {
return false;
}
}
final BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
if (device == null) {
Log.w(TAG, "Device not found. Unable to connect.");
return false;
}
// We want to directly connect to the device, so we are setting the autoConnect
// parameter to false.
mBluetoothGatt = device.connectGatt(this, false, mGattCallback);
Log.d(TAG, "Trying to create a new connection.");
mBluetoothDeviceAddress = address;
mConnectionState = STATE_CONNECTING;
return true;
}
/**
* Disconnects an existing connection or cancel a pending connection. The disconnection result
* is reported asynchronously through the
* {@code BluetoothGattCallback#onConnectionStateChange(android.bluetooth.BluetoothGatt, int, int)}
* callback.
*/
public void disconnect() {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.disconnect();
}
/**
* After using a given BLE device, the app must call this method to ensure resources are
* released properly.
*/
public void close() {
if (mBluetoothGatt == null) {
return;
}
mBluetoothGatt.close();
mBluetoothGatt = null;
}
/**
* Request a read on a given {@code BluetoothGattCharacteristic}. The read result is reported
* asynchronously through the {@code BluetoothGattCallback#onCharacteristicRead(android.bluetooth.BluetoothGatt, android.bluetooth.BluetoothGattCharacteristic, int)}
* callback.
*
* @param characteristic The characteristic to read from.
*/
public void readCharacteristic(BluetoothGattCharacteristic characteristic) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.readCharacteristic(characteristic);
}
/**
* Request a read on a given {@code BluetoothGattCharacteristic}. The read result is reported
* asynchronously through the {@code BluetoothGattCallback#onCharacteristicRead(android.bluetooth.BluetoothGatt, android.bluetooth.BluetoothGattCharacteristic, int)}
* callback.
*
* @param characteristic The characteristic to read from.
*/
public void writeCharacteristic(BluetoothGattCharacteristic characteristic) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.writeCharacteristic(characteristic);
}
public boolean writeCharacteristic1Info(String s){
if(mBluetoothGattService==null){
return false;
}
mBluetoothGattCharacteristic1 = mBluetoothGattService.getCharacteristic(UUID_CHARA1);//获得特征值1
mBluetoothGattCharacteristic1.setValue(s.getBytes());
writeCharacteristic(mBluetoothGattCharacteristic1);
return true;
}
/**
* Enables or disables notification on a give characteristic.
*
* @param characteristic Characteristic to act on.
* @param enabled If true, enable notification. False otherwise.
*/
public void setCharacteristicNotification(BluetoothGattCharacteristic characteristic,
boolean enabled) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.setCharacteristicNotification(characteristic, enabled);
}
/**
* Retrieves a list of supported GATT services on the connected device. This should be
* invoked only after {@code BluetoothGatt#discoverServices()} completes successfully.
*
* @return A {@code List} of supported services.
*/
public List<BluetoothGattService> getSupportedGattServices() {
if (mBluetoothGatt == null) return null;
return mBluetoothGatt.getServices();
}
@Override//使用startService启动服务时回调
public int onStartCommand(Intent intent, int flags, int startId) {
System.out.println("UartService Start");
return super.onStartCommand(intent, flags, startId);
}
}
ps：在发现服务后，最好把特征值取出来成一个列表，然后使用 setCharacteristicNotification(BluetoothGattCharacteristic characteristic,boolean enabled)方法对所有特征值进行设置，确保服务的特征值都可读可写。
mBluetoothGattService = gatt.getService(UUID_SERVICE);//发现服务
List<BluetoothGattCharacteristic> characteristics = mBluetoothGattService.getCharacteristics();
if(characteristics.size()!=2){return;}//如果此服务不是有2个特征值，说明不是我们要的服务
for (BluetoothGattCharacteristic bluetoothGattCharacteristic : characteristics) {
setCharacteristicNotification(bluetoothGattCharacteristic, true);
}
mBluetoothGattCharacteristic1 = characteristics.get(0);
mBluetoothGattCharacteristic2 = characteristics.get(1);
写完Service之后就可以用Service了
四、Service的使用
- 在activity中绑定服务或者开启服务。绑定服务时，当activity销毁时服务跟着销毁；开启服务时，activity销毁，service不会跟着销毁
- 初始化本地蓝牙设备
mUartService.initialize();//初始化本地设备
- 连接
mUartService.connect(String MacAddress);//通过远程设备地址链接到远程设备
- 链接后，回掉service中的onConnectionStateChange方法，其他的回掉方法也是字面意思，非常简单
- 给设备发送数据
writeCharacteristic1Info(String s);
总结
- 要使用service
- 拿到服务之后马上设置特征值为可读可写，否则有可能导致收发数据不正常
- UUID不一定是我的这个，是蓝牙厂商提供的，找硬件编程的小伙伴要UUID
- 有什么问题望各位指教
时间： 2024-10-13 23:04:31