Android蓝牙通信

浏览数：31 / 时间：2015年06月11日

Android为蓝牙设备之间的通信封装好了一些调用接口，使得实现Android的蓝牙通信功能并不困难。可通过UUID使两个设备直接建立连接。

具体步骤：

1. 获取BluetoothAdapter实例，注册一个BroadcastReceiver监听蓝牙扫描过程中的状态变化

1	`mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();`

1 2	`IntentFilter filter =` `new` `IntentFilter(BluetoothDevice.ACTION_FOUND);` `registerReceiver(mReceiver, filter);`

private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
 
 
            // When discovery finds a device
            if (BluetoothDevice.ACTION_FOUND.equals(action)) 
            {
                // Get the BluetoothDevice object from the Intent
                // 通过EXTRA_DEVICE附加域来得到一个BluetoothDevice设备
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                 
                // If it‘s already paired, skip it, because it‘s been listed already
                // 如果这个设备是不曾配对过的，添加到list列表
                if (device.getBondState() != BluetoothDevice.BOND_BONDED) 
                {
                    list.add(new ChatMessage(device.getName() + "\n" + device.getAddress(), false));
                    clientAdapter.notifyDataSetChanged();
                    mListView.setSelection(list.size() - 1);
                }
            // When discovery is finished, change the Activity title
            } 
            else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) 
            {
                setProgressBarIndeterminateVisibility(false);
                if (mListView.getCount() == 0) 
                {
                    list.add(new ChatMessage("没有发现蓝牙设备", false));
                    clientAdapter.notifyDataSetChanged();
                    mListView.setSelection(list.size() - 1);
                }
            }
        }
    };

2. 打开蓝牙(enable)，并设置蓝牙的可见性(可以被其它设备扫描到，客户端是主动发请求的，可不设置，服务端必须设置可见)。

       if (mBluetoothAdapter != null) {
    if (!mBluetoothAdapter.isEnabled()) {
        // 发送打开蓝牙的意图，系统会弹出一个提示对话框
        Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableIntent, RESULT_FIRST_USER);
         
        // 设置蓝牙的可见性，最大值3600秒，默认120秒，0表示永远可见(作为客户端，可见性可以不设置，服务端必须要设置)
        Intent displayIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
        displayIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 0);
        startActivity(displayIntent);
         
        // 直接打开蓝牙
        mBluetoothAdapter.enable();
    }
}

3. 扫描，startDiscovery()方法是一个很耗性能的操作，在扫描之前可以先使用getBondedDevices()获取已经配对过的设备(可直接连接)，避免不必要的消耗。

  private void scanDevice() {
    // TODO Auto-generated method stub
    if (mBluetoothAdapter.isDiscovering()) {
        mBluetoothAdapter.cancelDiscovery();
    } else {
         
        // 每次扫描前都先判断一下是否存在已经配对过的设备
        Set<bluetoothdevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
        if (pairedDevices.size() > 0) {
            for (BluetoothDevice device : pairedDevices) {
                list.add(new ChatMessage(device.getName() + "\n" + device.getAddress(), true));
            }
        } else {
                list.add(new ChatMessage("No devices have been paired", true));
                clientAdapter.notifyDataSetChanged();
                mListView.setSelection(list.size() - 1);
         }              
             /* 开始搜索 */
             mBluetoothAdapter.startDiscovery();
    }
}</bluetoothdevice>

4. 通过Mac地址发送连接请求，在这之前必须使用cancelDiscovery()方法停止扫描。

        mBluetoothAdapter.cancelDiscovery();
 
// 通过Mac地址去尝试连接一个设备
BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(BluetoothMsg.BlueToothAddress);

5. 通过UUID使两个设备之间建立连接。

客户端：主动发请求

BluetoothSocket socket = device.createRfcommSocketToServiceRecord(UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"));
                
// 通过socket连接服务器，这是一个阻塞过程，直到连接建立或者连接失效
socket.connect();

服务端：接受一个请求

BluetoothServerSocket mServerSocket = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(PROTOCOL_SCHEME_RFCOMM,
                   UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"));       
            
/* 接受客户端的连接请求 */
// 这是一个阻塞过程，直到建立一个连接或者连接失效
// 通过BluetoothServerSocket得到一个BluetoothSocket对象，管理这个连接
BluetoothSocket socket = mServerSocket.accept();

6. 通过InputStream／outputStream读写数据流，已达到通信目的。

1 2	`OutputStream os = socket.getOutputStream();` `os.write(msg.getBytes());`

InputStream is = null;
try {
    is = socket.getInputStream();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

7. 关闭所有线程以及socket，并关闭蓝牙设备(disable)。

        if (mClientThread != null) {
    mClientThread.interrupt();
    mClientThread = null;
}
if (mReadThread != null) {
    mReadThread.interrupt();
    mReadThread = null;
}
try {
    if (socket != null) {
        socket.close();
        socket = null;
    }
} catch (IOException e) {
    // TODO: handle exception
}

        if (mBluetoothAdapter != null) {
    mBluetoothAdapter.cancelDiscovery();
    // 关闭蓝牙
    mBluetoothAdapter.disable();
}
unregisterReceiver(mReceiver);