Android 蓝牙开发浅析

 

Android Bluetooth API 翻译http://wenku.baidu.com/view/518414b069dc5022aaea007b.html?from=rec&pos=2&weight=167&lastweight=111&count=5

 

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);
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 private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
03     public void onReceive(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 = 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;
03
04     public AcceptThread() {
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     public void run() {
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     public void cancel() {
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>    private class ConnectThread extends Thread {
02         private final BluetoothSocket mmSocket;
03         private final BluetoothDevice mmDevice;
04
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;
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         public void run() {
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         public void cancel() {
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>    private class ConnectedThread extends Thread {
02         private final BluetoothSocket mmSocket;
03         private final InputStream mmInStream;
04         private final OutputStream mmOutStream;
05
06         public ConnectedThread(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         public void run() {
23             byte[] buffer = new byte[1024];  // buffer store for the stream
24             int bytes; // bytes returned from read()
25
26             // Keep listening to the InputStream until an exception occurs
27             while (true) {
28                 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) {
35                     break;
36                 }
37             }
38         }
39
40         /* Call this from the main Activity to send data to the remote device */
41         public void write(byte[] bytes) {
42             try {
43                 mmOutStream.write(bytes);
44             } catch (IOException e) { }
45         }
46
47         /* Call this from the main Activity to shutdown the connection */
48         public void cancel() {
49             try {
50                 mmSocket.close();
51             } catch (IOException e) { }
52         }
53     }  </STRONG>

 

 

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