Android 蓝牙开发浅析

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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

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BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();   

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//直接打开系统的蓝牙设置面板   

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Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);   

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startActivityForResult(intent, 0x1);   

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//直接打开蓝牙   

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adapter.enable();   

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//关闭蓝牙   

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adapter.disable();   

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//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）   

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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

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// 创建一个接收ACTION_FOUND广播的BroadcastReceiver   

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private final BroadcastReceiver mReceiver = new BroadcastReceiver() {   

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    public void onReceive(Context context, Intent intent) {   

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        String action = intent.getAction();   

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        // 发现设备   

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

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            // 从Intent中获取设备对象   

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

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

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

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        }   

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    }   

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};   

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// 注册BroadcastReceiver   

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IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);   

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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）

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private class AcceptThread extends Thread { 

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    private final BluetoothServerSocket mmServerSocket; 

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    public AcceptThread() { 

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

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        // because mmServerSocket is final 

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        BluetoothServerSocket tmp = null; 

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        try { 

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

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            tmp = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID); 

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        } catch (IOException e) { } 

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        mmServerSocket = tmp; 

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    } 

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    public void run() { 

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        BluetoothSocket socket = null; 

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

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        while (true) { 

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            try { 

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                socket = mmServerSocket.accept(); 

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            } catch (IOException e) { 

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                break; 

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            } 

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            // If a connection was accepted 

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            if (socket != null) { 

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

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                manageConnectedSocket(socket); 

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                mmServerSocket.close(); 

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                break; 

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            } 

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        } 

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    } 

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

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    public void cancel() { 

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        try { 

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            mmServerSocket.close(); 

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        } catch (IOException e) { } 

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    } 

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}

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

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<STRONG>    private class ConnectThread extends Thread {   

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        private final BluetoothSocket mmSocket;   

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        private final BluetoothDevice mmDevice;   

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        public ConnectThread(BluetoothDevice device) {   

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

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            // because mmSocket is final   

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            BluetoothSocket tmp = null;   

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            mmDevice = device;   

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            // Get a BluetoothSocket to connect with the given BluetoothDevice   

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            try {   

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

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                tmp = device.createRfcommSocketToServiceRecord(MY_UUID);   

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            } catch (IOException e) { }   

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            mmSocket = tmp;   

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        }   

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        public void run() {   

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            // Cancel discovery because it will slow down the connection   

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            mBluetoothAdapter.cancelDiscovery();   

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            try {   

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

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                // until it succeeds or throws an exception   

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                mmSocket.connect();   

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            } catch (IOException connectException) {   

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

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                try {   

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                    mmSocket.close();   

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                } catch (IOException closeException) { }   

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                return;   

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            }   

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

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            manageConnectedSocket(mmSocket);   

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        }   

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

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        public void cancel() {   

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            try {   

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                mmSocket.close();   

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            } catch (IOException e) { }   

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        }   

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    }  </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）

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<STRONG>    private class ConnectedThread extends Thread {   

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        private final BluetoothSocket mmSocket;   

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        private final InputStream mmInStream;   

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        private final OutputStream mmOutStream;   

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        public ConnectedThread(BluetoothSocket socket) {   

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            mmSocket = socket;   

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            InputStream tmpIn = null;   

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            OutputStream tmpOut = null;   

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

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            // member streams are final   

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            try {   

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                tmpIn = socket.getInputStream();   

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                tmpOut = socket.getOutputStream();   

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            } catch (IOException e) { }   

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            mmInStream = tmpIn;   

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            mmOutStream = tmpOut;   

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        }   

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        public void run() {   

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

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            int bytes; // bytes returned from read()   

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            // Keep listening to the InputStream until an exception occurs   

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            while (true) {   

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                try {   

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                    // Read from the InputStream   

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                    bytes = mmInStream.read(buffer);   

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                    // Send the obtained bytes to the UI Activity   

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

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                            .sendToTarget();   

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                } catch (IOException e) {   

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                    break;   

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                }   

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            }   

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        }   

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

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        public void write(byte[] bytes) {   

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            try {   

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                mmOutStream.write(bytes);   

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            } catch (IOException e) { }   

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        }   

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

48
        public void cancel() {   

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            try {   

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                mmSocket.close();   

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            } catch (IOException e) { }   

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        }   

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    }  </STRONG>

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