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()、
。
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
。