android 蓝牙

1. 使用蓝牙的响应权限

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

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）  discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);//设置持续时间（最多300秒）Intent discoveryIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);

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

<strong>    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) { }          }      }  </strong>

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）

<strong>    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) { }          }      }  </strong>

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