传输蓝牙数据

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：

1. 获取 InputStream 和 处理传输的 OutputStream 使用套接字 getInputStream() 和 getOutputStream()、 。

2. 使用 read(byte[])和 write(byte[])。

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 。