Android(安卓)蓝牙开发浅析

1. 使用蓝牙的响应权限

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

`2`	`<uses-permissionandroid: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 =newIntent(BluetoothAdapter.ACTION_REQUEST_ENABLE);`

`04`	`startActivityForResult(intent,0x1);`

`05`	`//直接打开蓝牙`

`06`	`adapter.enable();`

07 //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`	`privatefinalBroadcastReceiver mReceiver =newBroadcastReceiver() {`

`03`	`publicvoidonReceive(Context context, Intent intent) {`

`04`	`String action = intent.getAction();`

05 // 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());`

11 }

12 }

13 };

`14`	`// 注册BroadcastReceiver`

`15`	`IntentFilter filter =newIntentFilter(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`	`privateclassAcceptThreadextendsThread {`

`02`	`privatefinalBluetoothServerSocket mmServerSocket;`

03

`04`	`publicAcceptThread() {`

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

`06`	`// because mmServerSocket is final`

`07`	`BluetoothServerSocket tmp =null;`

08 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;`

13 }

14

`15`	`publicvoidrun() {`

`16`	`BluetoothSocket socket =null;`

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

`18`	`while(true) {`

19 try{

`20`	`socket = mmServerSocket.accept();`

`21`	`}catch(IOException e) {`

22 break;

23 }

`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();`

29 break;

30 }

31 }

32 }

33

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

`35`	`publicvoidcancel() {`

36 try{

`37`	`mmServerSocket.close();`

`38`	`}catch(IOException e) { }`

39 }

40 }

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>privateclassConnectThreadextendsThread {`

`02`	`privatefinalBluetoothSocket mmSocket;`

`03`	`privatefinalBluetoothDevice mmDevice;`

04

`05`	`publicConnectThread(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;`

10

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

12 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;`

17 }

18

`19`	`publicvoidrun() {`

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

`21`	`mBluetoothAdapter.cancelDiscovery();`

22

23 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`

29 try{

`30`	`mmSocket.close();`

`31`	`}catch(IOException closeException) { }`

32 return;

33 }

34

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

`36`	`manageConnectedSocket(mmSocket);`

37 }

38

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

`40`	`publicvoidcancel() {`

41 try{

`42`	`mmSocket.close();`

`43`	`}catch(IOException e) { }`

44 }

`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>privateclassConnectedThreadextendsThread {`

`02`	`privatefinalBluetoothSocket mmSocket;`

`03`	`privatefinalInputStream mmInStream;`

`04`	`privatefinalOutputStream mmOutStream;`

05

`06`	`publicConnectedThread(BluetoothSocket socket) {`

`07`	`mmSocket = socket;`

`08`	`InputStream tmpIn =null;`

`09`	`OutputStream tmpOut =null;`

10

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

`12`	`// member streams are final`

13 try{

`14`	`tmpIn = socket.getInputStream();`

`15`	`tmpOut = socket.getOutputStream();`

`16`	`}catch(IOException e) { }`

17

`18`	`mmInStream = tmpIn;`

`19`	`mmOutStream = tmpOut;`

20 }

21

`22`	`publicvoidrun() {`

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

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