在您成功连接到蓝牙后
设备,每个
有一个已连接的
BluetoothSocket
。现在,您可以
在设备之间共享信息。使用 BluetoothSocket
,
数据转移过程如下所示:
获取
InputStream
和 处理传输的OutputStream
使用套接字getInputStream()
和getOutputStream()
、 。
当然,还需要考虑实现细节。具体而言,您
应使用专门的线程从数据流读取数据和向数据流写入数据。
这一点很重要,因为 read(byte[])
和 write(byte[])
方法
正在屏蔽来电。read(byte[])
方法会阻塞,直到有需要处理的内容
从数据流中读取的内容。write(byte[])
方法通常不会阻塞,
如果远程设备未调用 read(byte[])
,则可以屏蔽以实施流控制
使中间缓冲区填满。因此,
应将线程中的主循环专门用于从 InputStream
读取数据。
您可以在线程中使用单独的公共方法向
OutputStream
。
示例
以下示例展示了如何在两台设备之间传输数据 通过蓝牙连接:
Kotlin
private const val TAG = "MY_APP_DEBUG_TAG" // Defines several constants used when transmitting messages between the // service and the UI. const val MESSAGE_READ: Int = 0 const val MESSAGE_WRITE: Int = 1 const val MESSAGE_TOAST: Int = 2 // ... (Add other message types here as needed.) class MyBluetoothService( // handler that gets info from Bluetooth service private val handler: Handler) { private inner class ConnectedThread(private val mmSocket: BluetoothSocket) : Thread() { private val mmInStream: InputStream = mmSocket.inputStream private val mmOutStream: OutputStream = mmSocket.outputStream private val mmBuffer: ByteArray = ByteArray(1024) // mmBuffer store for the stream override fun run() { var numBytes: Int // bytes returned from read() // Keep listening to the InputStream until an exception occurs. while (true) { // Read from the InputStream. numBytes = try { mmInStream.read(mmBuffer) } catch (e: IOException) { Log.d(TAG, "Input stream was disconnected", e) break } // Send the obtained bytes to the UI activity. val readMsg = handler.obtainMessage( MESSAGE_READ, numBytes, -1, mmBuffer) readMsg.sendToTarget() } } // Call this from the main activity to send data to the remote device. fun write(bytes: ByteArray) { try { mmOutStream.write(bytes) } catch (e: IOException) { Log.e(TAG, "Error occurred when sending data", e) // Send a failure message back to the activity. val writeErrorMsg = handler.obtainMessage(MESSAGE_TOAST) val bundle = Bundle().apply { putString("toast", "Couldn't send data to the other device") } writeErrorMsg.data = bundle handler.sendMessage(writeErrorMsg) return } // Share the sent message with the UI activity. val writtenMsg = handler.obtainMessage( MESSAGE_WRITE, -1, -1, mmBuffer) writtenMsg.sendToTarget() } // Call this method from the main activity to shut down the connection. fun cancel() { try { mmSocket.close() } catch (e: IOException) { Log.e(TAG, "Could not close the connect socket", e) } } } }
Java
public class MyBluetoothService { private static final String TAG = "MY_APP_DEBUG_TAG"; private Handler handler; // handler that gets info from Bluetooth service // Defines several constants used when transmitting messages between the // service and the UI. private interface MessageConstants { public static final int MESSAGE_READ = 0; public static final int MESSAGE_WRITE = 1; public static final int MESSAGE_TOAST = 2; // ... (Add other message types here as needed.) } private class ConnectedThread extends Thread { private final BluetoothSocket mmSocket; private final InputStream mmInStream; private final OutputStream mmOutStream; private byte[] mmBuffer; // mmBuffer store for the stream 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(); } catch (IOException e) { Log.e(TAG, "Error occurred when creating input stream", e); } try { tmpOut = socket.getOutputStream(); } catch (IOException e) { Log.e(TAG, "Error occurred when creating output stream", e); } mmInStream = tmpIn; mmOutStream = tmpOut; } public void run() { mmBuffer = new byte[1024]; int numBytes; // bytes returned from read() // Keep listening to the InputStream until an exception occurs. while (true) { try { // Read from the InputStream. numBytes = mmInStream.read(mmBuffer); // Send the obtained bytes to the UI activity. Message readMsg = handler.obtainMessage( MessageConstants.MESSAGE_READ, numBytes, -1, mmBuffer); readMsg.sendToTarget(); } catch (IOException e) { Log.d(TAG, "Input stream was disconnected", e); break; } } } // Call this from the main activity to send data to the remote device. public void write(byte[] bytes) { try { mmOutStream.write(bytes); // Share the sent message with the UI activity. Message writtenMsg = handler.obtainMessage( MessageConstants.MESSAGE_WRITE, -1, -1, mmBuffer); writtenMsg.sendToTarget(); } catch (IOException e) { Log.e(TAG, "Error occurred when sending data", e); // Send a failure message back to the activity. Message writeErrorMsg = handler.obtainMessage(MessageConstants.MESSAGE_TOAST); Bundle bundle = new Bundle(); bundle.putString("toast", "Couldn't send data to the other device"); writeErrorMsg.setData(bundle); handler.sendMessage(writeErrorMsg); } } // Call this method from the main activity to shut down the connection. public void cancel() { try { mmSocket.close(); } catch (IOException e) { Log.e(TAG, "Could not close the connect socket", e); } } } }
在构造函数获取必要的流后,线程会等待数据
通过 InputStream
进行传输。当 read(byte[])
返回以下项中的数据时:
则数据会通过成员的
父类的 Handler
。线程
然后等待从 InputStream
中读取更多字节。
如需发送传出数据,请从主线程调用线程的 write()
方法
activity 并传入要发送的字节。此方法会调用 write(byte[])
,以
将数据发送到远程设备。如果
调用时抛出 IOException
write(byte[])
,线程会向主 activity 发送一个消息框,向
设备无法向对方发送给定字节的用户
(已连接)设备。
线程的 cancel()
方法让您可以在任意时刻终止连接
关闭BluetoothSocket
即可完成操作后,一律调用此方法。
使用蓝牙连接。
有关使用 Bluetooth API 的演示,请参阅蓝牙聊天示例 应用 。