Android 藍芽 通訊

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Android中藍芽模組的使用

1. 使用藍芽的響應許可權

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

 

2. 配置本機藍芽模組

在這裡首先要瞭解對藍芽操作一個核心類BluetoothAdapter

BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();  //直接開啟系統的藍芽設定面板  Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);  startActivityForResult(intent, 0x1);  //直接開啟藍芽  adapter.enable();  //關閉藍芽  adapter.disable();  //開啟原生藍芽發現功能（預設開啟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);//設定期間（最多300秒）  

3.搜尋藍牙裝置

使用BluetoothAdapter的startDiscovery()方法來搜尋藍牙裝置

startDiscovery()方法是一個非同步方法呼叫，調用後會立即返回。該方法會進行對其他藍牙裝置的搜尋，該過程會持續12秒。該方法調用後，搜尋過程實際上是在一個System Service中進行的，所以可以調用cancelDiscovery()方法來停止搜尋（該方法可以在未執行discovery請求時調用）。

請求Discovery後，系統開始搜尋藍牙裝置，在這個過程中，系統會發送以下三個廣播：

ACTION_DISCOVERY_START：開始搜尋

ACTION_DISCOVERY_FINISHED：搜尋結束

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

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

// 建立一個接收ACTION_FOUND廣播的BroadcastReceiver  private final BroadcastReceiver mReceiver = new BroadcastReceiver() {      public void onReceive(Context context, Intent intent) {          String action = intent.getAction();          // 發現裝置          if (BluetoothDevice.ACTION_FOUND.equals(action)) {              // 從Intent中擷取裝置對象              BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);              // 將裝置名稱和地址放入array adapter，以便在ListView中顯示              mArrayAdapter.add(device.getName() + "\n" + device.getAddress());          }      }  };  // 註冊BroadcastReceiver  IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);  registerReceiver(mReceiver, filter); // 不要忘了之後解除綁定   

4. 藍芽Socket通訊

如果打算建議兩個藍牙裝置之間的串連，則必須實現伺服器端與用戶端的機制。當兩個裝置在同一個RFCOMM channel下分別擁有一個串連的BluetoothSocket，這兩個裝置才可以說是建立了串連。

伺服器裝置與用戶端裝置擷取BluetoothSocket的途徑是不同的。伺服器裝置是通過accepted一個incoming connection來擷取的，而用戶端裝置則是通過開啟一個到伺服器的RFCOMM channel來擷取的。

 

伺服器端的實現

通過調用BluetoothAdapter的listenUsingRfcommWithServiceRecord(String, UUID)方法來擷取BluetoothServerSocket（UUID用於用戶端與伺服器端之間的配對）

調用BluetoothServerSocket的accept()方法監聽串連請求，如果收到請求，則返回一個BluetoothSocket執行個體（此方法為block方法，應置於新線程中）

如果不想在accept其他的串連，則調用BluetoothServerSocket的close()方法釋放資源（調用該方法後，之前獲得的BluetoothSocket執行個體並沒有close。但由於RFCOMM一個時刻只允許在一條channel中有一個串連，則一般在accept一個串連後，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) { }      }  }   

用戶端的實現

通過搜尋得到伺服器端的BluetoothService

調用BluetoothService的listenUsingRfcommWithServiceRecord(String, UUID)方法擷取BluetoothSocket（該UUID應該同於伺服器端的UUID）

調用BluetoothSocket的connect()方法（該方法為block方法），如果UUID同伺服器端的UUID匹配，並且串連被伺服器端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尋裝置，否則串連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) { }      }  }  

串連管理（資料通訊）

分別通過BluetoothSocket的getInputStream()和getOutputStream()方法擷取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，知道從流中讀取到資訊，而write(bytes[])方法並不是經常的block（比如在另一裝置沒有及時read或者中間緩衝區已滿的情況下，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) { }      }  }  

 

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

 

Android 藍芽 通訊