Android 蓝牙 socket通信

Android中蓝牙模块的使用

使用蓝牙API，Android应用程序能够执行以下功能：

扫描其他蓝牙设备查询本地已经配对的蓝牙适配器建立RFCOMM通道
通过服务发现来连接其他设备
在设备间传输数据
管理多个蓝牙连接

本文介绍如何使用Android的蓝牙API来完成使用蓝牙通信所需要的四项主要任务：设置蓝牙、查找已配对或区域内可用的蓝牙设备、连接设备、设备间传输数据。

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) { }  

    }  

}  

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) { }  

    }  

}  

 

摘自：http://blog.csdn.net/geekdonie/article/details/7487761