Android 蓝牙开发实例解析

在使用手机时，蓝牙通信给我们带来很多方便。那么在Android手机中怎样进行蓝牙开发呢？本文以实例的方式讲解Android蓝牙开发的知识。

       1、使用蓝牙的响应权限

XML/HTML代码

<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) { }
  }
} 

       5、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) { }  

 }  

}  

以上就Android 蓝牙的开发简单示例代码，后续继续整理相关资料，谢谢大家对本站的支持！