Hi,
I am currently developing a project which needs to write/read data via
bluetooth.
I met a werid problem when I try to use a handler to deal with the
information back from the service I created.
When I put a breakpoint after " bytes = mmInStream.read(buffer);
" ( in ConnectedThread.run() )
I can see the content in the buffer is:
[2, 0, 8, 3, -15, 16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 99, 12, 30, 99, 0, 99, 127,
99, 51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
119, 30, 12, 103, 0, 119, 70, 103, 51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 127, 51, 12, 111, 0, 127, 22, 111,
51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
107, 51, 12, 123, 0, 107, 30, 123, 51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 99, 63, 12, 115, 0, 99, 22, 115, 51,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 99, 51,
12, 99, 0, 99, 70, 99, 51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 99, 51, 30, 99, 0, 99, 127, 99, 63, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -23, 4, ....many
0s...]
and the bytes = 248.
These are what I expected.
However, in the hanlder, the content of readBuf becomes:
[99, 51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 99, 51, 30, 99, 0, 99, 127, 99, 63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -23, 4, 0, 0, 0, 0, 0, 0, 107, 51,
12, 123, 0, 107, 30, 123, 51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 99, 63, 12, 115, 0, 99, 22, 115, 51, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 99, 51, 12, 99,
0, 99, 70, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, ...many 0s...]
The werid thing is, if the "bytes = mmInStream.read(buffer);" reads
[2, 0, 8, 3, 31, 32, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 55, 4, ...many 0s...],
(bytes = 38 in this case)
then the handler can get the correct content.
I cannot figure out why, I think it is a handler mistake, any hint?
API Level: 13
The source code is based on the BluetoothChat sample, if needed, I can
provide more detailed code.
--------------------------------
Service------------------------------------------------
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
Log.d(TAG, "create ConnectedThread");
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the BluetoothSocket input and output streams
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.e(TAG, "temp sockets not created", e);
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
Log.i(TAG, "BEGIN mConnectedThread");
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI
Activity
mHandler.obtainMessage(ControlActivity.MESSAGE_READ, bytes, -1,
buffer).sendToTarget();
} catch (IOException e) {
Log.e(TAG, "disconnected", e);
connectionLost();
break;
}
}
}
...
}
------------------------------handler in Activity
class--------------------------------------------------
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
...
case MESSAGE_READ:
byte[] readBuf = (byte[]) msg.obj;
...
}
}
}
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