Android 藍牙開發實例解析

在使用手機時，藍牙通信給我們帶來很多方便。那麼在Android手機中怎樣進行藍牙開發呢？本文以實例的方式講解Android藍牙開發的知識。

       1、使用藍牙的響應權限

XML/HTML代碼

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

        2、配置本機藍牙模塊

       在這裡首先要了解對藍牙操作一個核心類BluetoothAdapter。

BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();  
  
//直接打開系統的藍牙設置面板  
  
Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);  
  
startActivityForResult(intent, 0x1);  
  
//直接打開藍牙  
  
adapter.enable();  
  
//關閉藍牙  
  
adapter.disable();  
  
//打開本機的藍牙發現功能（默認打開120秒，可以將時間最多延長至300秒）  
  
Intent discoveryIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);  
  
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);//設置持續時間（最多300秒） 

         3、搜索藍牙設備

       使用BluetoothAdapter的startDiscovery()方法來搜索藍牙設備。

       startDiscovery()方法是一個異步方法，調用後會立即返回。該方法會進行對其他藍牙設備的搜索，該過程會持續12秒。該方法調用後，搜索過程實際上是在一個System Service中進行的，所以可以調用cancelDiscovery()方法來停止搜索（該方法可以在未執行discovery請求時調用）。

       請求Discovery後，系統開始搜索藍牙設備，在這個過程中，系統會發送以下三個廣播：

       ACTION_DISCOVERY_START：開始搜索

       ACTION_DISCOVERY_FINISHED：搜索結束

       ACTION_FOUND：找到設備，這個Intent中包含兩個extra fields：EXTRA_DEVICE和EXTRA_CLASS，分別包含BluetooDevice和BluetoothClass。

       我們可以自己注冊相應的BroadcastReceiver來接收響應的廣播，以便實現某些功能。

// 創建一個接收ACTION_FOUND廣播的BroadcastReceiver  
  
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {  
  
 public void onReceive(Context context, Intent intent) {  
  
  String action = intent.getAction();  
  
  // 發現設備  
  
  if (BluetoothDevice.ACTION_FOUND.equals(action)) {  
  
   // 從Intent中獲取設備對象  
  
   BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);  
  
   // 將設備名稱和地址放入array adapter，以便在ListView中顯示  
  
   mArrayAdapter.add(device.getName() + "\n" + device.getAddress());  
  }  
 }  
};  
  
// 注冊BroadcastReceiver  
  
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);  
  
registerReceiver(mReceiver, filter); // 不要忘了之後解除綁定 

        4、藍牙Socket通信

       如果打算建議兩個藍牙設備之間的連接，則必須實現服務器端與客戶端的機制。當兩個設備在同一個RFCOMM channel下分別擁有一個連接的BluetoothSocket，這兩個設備才可以說是建立了連接。

       服務器設備與客戶端設備獲取BluetoothSocket的途徑是不同的。服務器設備是通過accepted一個incoming connection來獲取的，而客戶端設備則是通過打開一個到服務器的RFCOMM channel來獲取的。

       服務器端的實現

       通過調用BluetoothAdapter的listenUsingRfcommWithServiceRecord(String, UUID)方法來獲取BluetoothServerSocket（UUID用於客戶端與服務器端之間的配對）。

       調用BluetoothServerSocket的accept()方法監聽連接請求，如果收到請求，則返回一個BluetoothSocket實例（此方法為block方法，應置於新線程中）。

       如果不想在accept其他的連接，則調用BluetoothServerSocket的close()方法釋放資源（調用該方法後，之前獲得的BluetoothSocket實例並沒有close。但由於RFCOMM一個時刻只允許在一條channel中有一個連接，則一般在accept一個連接後，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) { }  
 }  
} 

        客戶端的實現

       通過搜索得到服務器端的BluetoothService。

       調用BluetoothService的listenUsingRfcommWithServiceRecord(String, UUID)方法獲取BluetoothSocket（該UUID應該同於服務器端的UUID）。

       調用BluetoothSocket的connect()方法（該方法為block方法），如果UUID同服務器端的UUID匹配，並且連接被服務器端accept，則connect()方法返回。

       注意：在調用connect()方法之前，應當確定當前沒有搜索設備，否則連接會變得非常慢並且容易失敗。

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、連接管理（數據通信）

       分別通過BluetoothSocket的getInputStream()和getOutputStream()方法獲取InputStream和OutputStream。

       使用read(bytes[])和write(bytes[])方法分別進行讀寫操作。

       注意：read(bytes[])方法會一直block，知道從流中讀取到信息，而write(bytes[])方法並不是經常的block（比如在另一設備沒有及時read或者中間緩沖區已滿的情況下，write方法會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 藍牙的開發簡單示例代碼，後續繼續整理相關資料，謝謝大家對本站的支持！