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android 蓝牙开发浅析

2013-03-03 09:16 423 查看

转自 http://www.open-open.com/lib/view/open1335146166780.html
由于近期正在开发一个通过蓝牙进行数据传递的模块，在参考了有关资料，并详细阅读了Android的官方文档后，总结了Android中蓝牙模块的使用。

1. 使用蓝牙的响应权限

1	< strong > < uses-permission android:name = "android.permission.BLUETOOTH" />

2	< uses-permission android:name = "android.permission.BLUETOOTH_ADMIN" /> </ strong >

2. 配置本机蓝牙模块

在这里首先要了解对蓝牙操作一个核心类BluetoothAdapter

01	BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();

02	//直接打开系统的蓝牙设置面板

03	Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);

04	startActivityForResult(intent, 0x1 );

//直接打开蓝牙

06	adapter.enable();

//关闭蓝牙

08	adapter.disable();

09	//打开本机的蓝牙发现功能（默认打开120秒，可以将时间最多延长至300秒）

10	discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300 ); //设置持续时间（最多300秒）Intent discoveryIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);

3.搜索蓝牙设备

使用BluetoothAdapter的startDiscovery()方法来搜索蓝牙设备

startDiscovery()方法是一个异步方法，调用后会立即返回。该方法会进行对其他蓝牙设备的搜索，该过程会持续12秒。该方法调用后，搜索过程实际上是在一个System Service中进行的，所以可以调用cancelDiscovery()方法来停止搜索（该方法可以在未执行discovery请求时调用）。

请求Discovery后，系统开始搜索蓝牙设备，在这个过程中，系统会发送以下三个广播：

ACTION_DISCOVERY_START：开始搜索

ACTION_DISCOVERY_FINISHED：搜索结束

ACTION_FOUND：找到设备，这个Intent中包含两个extra fields：EXTRA_DEVICE和EXTRA_CLASS，分别包含BluetooDevice和BluetoothClass。

我们可以自己注册相应的BroadcastReceiver来接收响应的广播，以便实现某些功能

01	// 创建一个接收ACTION_FOUND广播的BroadcastReceiver

02	private final BroadcastReceiver mReceiver = new BroadcastReceiver() {

03	public void onReceive(Context context, Intent intent) {

04	String action = intent.getAction();

//
发现设备

06	if (BluetoothDevice.ACTION_FOUND.equals(action)) {

07	// 从Intent中获取设备对象

08	BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

09	// 将设备名称和地址放入array adapter，以便在ListView中显示

10	mArrayAdapter.add(device.getName() + "\n" + device.getAddress());

};

14	// 注册BroadcastReceiver

15	IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);

16	registerReceiver(mReceiver, filter); // 不要忘了之后解除绑定

4. 蓝牙Socket通信

如果打算建议两个蓝牙设备之间的连接，则必须实现服务器端与客户端的机制。当两个设备在同一个RFCOMM channel下分别拥有一个连接的BluetoothSocket，这两个设备才可以说是建立了连接。

服务器设备与客户端设备获取BluetoothSocket的途径是不同的。服务器设备是通过accepted一个incoming connection来获取的，而客户端设备则是通过打开一个到服务器的RFCOMM channel来获取的。

服务器端的实现

通过调用BluetoothAdapter的listenUsingRfcommWithServiceRecord(String, UUID)方法来获取BluetoothServerSocket（UUID用于客户端与服务器端之间的配对）

调用BluetoothServerSocket的accept()方法监听连接请求，如果收到请求，则返回一个BluetoothSocket实例（此方法为block方法，应置于新线程中）

如果不想在accept其他的连接，则调用BluetoothServerSocket的close()方法释放资源（调用该方法后，之前获得的BluetoothSocket实例并没有close。但由于RFCOMM一个时刻只允许在一条channel中有一个连接，则一般在accept一个连接后，便close掉BluetoothServerSocket）

01	private class AcceptThread extends Thread {

02	private final BluetoothServerSocket mmServerSocket;

04	public AcceptThread() {

05	// Use a temporary object that is later assigned to mmServerSocket,

06	// because mmServerSocket is final

07	BluetoothServerSocket tmp = null ;

try

09	// MY_UUID is the app's UUID string, also used by the client code

10	tmp = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID);

11	} catch (IOException e) {}

12	mmServerSocket = tmp;

15	public void run() {

16	BluetoothSocket socket = null ;

17	// Keep listening until exception occurs or a socket is returned

18	while ( true ) {

try

20	socket = mmServerSocket.accept();

21	} catch (IOException e) {

break

24	// If a connection was accepted

25	if (socket != null ) {

26	// Do work to manage the connection (in a separate thread)

27	manageConnectedSocket(socket);

28	mmServerSocket.close();

break

34	/** Will cancel the listening socket, and cause the thread to finish */

35	public void cancel() {

try

37	mmServerSocket.close();

38	} catch (IOException e) {}

客户端的实现

通过搜索得到服务器端的BluetoothService

调用BluetoothService的listenUsingRfcommWithServiceRecord(String, UUID)方法获取BluetoothSocket（该UUID应该同于服务器端的UUID）

调用BluetoothSocket的connect()方法（该方法为block方法），如果UUID同服务器端的UUID匹配，并且连接被服务器端accept，则connect()方法返回

注意：在调用connect()方法之前，应当确定当前没有搜索设备，否则连接会变得非常慢并且容易失败

01	<strong> private class ConnectThread extends Thread {

02	private final BluetoothSocket mmSocket;

03	private final BluetoothDevice mmDevice;

05	public ConnectThread(BluetoothDevice device) {

06	// Use a temporary object that is later assigned to mmSocket,

07	// because mmSocket is final

08	BluetoothSocket tmp = null ;

09	mmDevice = device;

11	// Get a BluetoothSocket to connect with the given BluetoothDevice

try

13	// MY_UUID is the app's UUID string, also used by the server code

14	tmp = device.createRfcommSocketToServiceRecord(MY_UUID);

15	} catch (IOException e) {}

16	mmSocket = tmp;

19	public void run() {

20	// Cancel discovery because it will slow down the connection

21	mBluetoothAdapter.cancelDiscovery();

try

24	// Connect the device through the socket. This will block

25	// until it succeeds or throws an exception

26	mmSocket.connect();

27	} catch (IOException connectException) {

28	// Unable to connect;close the socket and get out

try

30	mmSocket.close();

31	} catch (IOException closeException) {}

return

35	// Do work to manage the connection (in a separate thread)

36	manageConnectedSocket(mmSocket);

39	/** Will cancel an in-progress connection, and close the socket */

40	public void cancel() {

try

42	mmSocket.close();

43	} catch (IOException e) {}

45	} </strong>

连接管理（数据通信）

分别通过BluetoothSocket的getInputStream()和getOutputStream()方法获取InputStream和OutputStream

使用read(bytes[])和write(bytes[])方法分别进行读写操作

注意：read(bytes[])方法会一直block，知道从流中读取到信息，而write(bytes[])方法并不是经常的block（比如在另一设备没有及时read或者中间缓冲区已满的情况下，write方法会block）

01	<strong> private class ConnectedThread extends Thread {

02	private final BluetoothSocket mmSocket;

03	private final InputStream mmInStream;

04	private final OutputStream mmOutStream;

06	public ConnectedThread(BluetoothSocket socket) {

07	mmSocket = socket;

08	InputStream tmpIn = null ;

09	OutputStream tmpOut = null ;

11	// Get the input and output streams, using temp objects because

12	// member streams are final

try

14	tmpIn = socket.getInputStream();

15	tmpOut = socket.getOutputStream();

16	} catch (IOException e) {}

18	mmInStream = tmpIn;

19	mmOutStream = tmpOut;

22	public void run() {

23	byte [] buffer = new byte [ 1024 ]; // buffer store for the stream

24	int bytes; // bytes returned from read()

26	// Keep listening to the InputStream until an exception occurs

27	while ( true ) {

try

29	// Read from the InputStream

30	bytes = mmInStream.read(buffer);

31	// Send the obtained bytes to the UI Activity

32	mHandler.obtainMessage(MESSAGE_READ, bytes, - 1 , buffer)

33	.sendToTarget();

34	} catch (IOException e) {

break

40	/* Call this from the main Activity to send data to the remote device */

41	public void write(byte[] bytes) {

try
{

43	mmOutStream.write(bytes);

44	} catch (IOException e) {}

47	/* Call this from the main Activity to shutdown the connection */

48	public void cancel() {

try

50	mmSocket.close();

51	} catch (IOException e) {}

53	} </strong>

转自：http://blog.csdn.net/gd920129/article/details/7487761

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