[Android实例] android 蓝牙开发浅析

1. 使用蓝牙的响应权限

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

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

BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();

//直接打开系统的蓝牙设置面板

Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);

startActivityForResult(intent, 0x1);

//直接打开蓝牙

adapter.enable();

//关闭蓝牙

adapter.disable();

//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）

Intent discoveryIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);

discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);//设置持续时间（最多300秒）

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

// 创建一个接收ACTION_FOUND广播的BroadcastReceiver

private final BroadcastReceiver mReceiver = new BroadcastReceiver() {

    public void onReceive(Context context, Intent intent) {

        String action = intent.getAction();

        // 发现设备

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

            // 从Intent中获取设备对象

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

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

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

// 注册BroadcastReceiver

IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);

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）

private class AcceptThread extends Thread {

    private final BluetoothServerSocket mmServerSocket;

    public AcceptThread() {

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

        // because mmServerSocket is final

        BluetoothServerSocket tmp = null;

        try {

            // MY_UUID is the app's UUID string, also used by the client code
            tmp = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID);
        } catch (IOException e) { }
        mmServerSocket = tmp;
    }

    public void run() {
        BluetoothSocket socket = null;

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

        while (true) {
            try {
                socket = mmServerSocket.accept();
            } catch (IOException e) {
                break;
            }

            // If a connection was accepted
            if (socket != null) {
                // Do work to manage the connection (in a separate thread)
                manageConnectedSocket(socket);
                mmServerSocket.close();
                break;
            }
        }
    }

    /** Will cancel the listening socket, and cause the thread to finish */
    public void cancel() {
        try {
            mmServerSocket.close();
        } 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

private class ConnectThread extends Thread {      private final BluetoothSocket mmSocket;

    private final BluetoothDevice mmDevice;



    public ConnectThread(BluetoothDevice device) {

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

        // because mmSocket is final

        BluetoothSocket tmp = null;

        mmDevice = device;



        // Get a BluetoothSocket to connect with the given BluetoothDevice

        try {

            // MY_UUID is the app's UUID string, also used by the server code
            tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
        } catch (IOException e) { }
        mmSocket = tmp;
    }



    public void run() {
        // Cancel discovery because it will slow down the connection
        mBluetoothAdapter.cancelDiscovery();
        try {
            // Connect the device through the socket. This will block
            // until it succeeds or throws an exception
            mmSocket.connect();
        } catch (IOException connectException) {

            // Unable to connect; close the socket and get out
            try {
                mmSocket.close();
            } catch (IOException closeException) { }
             return;
        }

          // Do work to manage the connection (in a separate thread)
        manageConnectedSocket(mmSocket);
    }

    /** Will cancel an in-progress connection, and close the socket */
     public void cancel() {
        try {
            mmSocket.close();

        } catch (IOException e) { }
     }
}

4.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）

private class ConnectedThread extends Thread {

    private final BluetoothSocket mmSocket;

    private final InputStream mmInStream;

    private final OutputStream mmOutStream;



    public ConnectedThread(BluetoothSocket socket) {

        mmSocket = socket;

        InputStream tmpIn = null;

        OutputStream tmpOut = null;



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

        // member streams are final

        try {

            tmpIn = socket.getInputStream();

            tmpOut = socket.getOutputStream();

        } catch (IOException e) { }



        mmInStream = tmpIn;

        mmOutStream = tmpOut;

    }



    public void run() {

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

        int bytes; // bytes returned from read()



        // Keep listening to the InputStream until an exception occurs

        while (true) {

            try {

                // Read from the InputStream

                bytes = mmInStream.read(buffer);

                // Send the obtained bytes to the UI Activity

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

                        .sendToTarget();

            } catch (IOException e) {

                break;

            }

        }

    }



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

    public void write(byte[] bytes) {

        try {

            mmOutStream.write(bytes);

        } catch (IOException e) { }

    }



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

    public void cancel() {

        try {

            mmSocket.close();

        } catch (IOException e) { }

    }

}