如何从特定线程发送udp数据报？

Question

I'm trying to send some udp datagrams which contain coded audio samples recorded via AudioRecord class. This android class provides a notification when a certain period of recording is elapsed and its safe to consume recorded data.

audioRecorder.setRecordPositionUpdateListener(new AudioRecord.OnRecordPositionUpdateListener() {

            @Override
            public void onPeriodicNotification(AudioRecord recorder) {
...

When the data are available I need to send them via udp like this:

audioRecorder.setRecordPositionUpdateListener(new AudioRecord.OnRecordPositionUpdateListener() {

            @Override
            public void onPeriodicNotification(AudioRecord recorder) {

                byte[] pcm = new byte[320];
                recorder.read(pcm, 0, 320);

                mapPcm16bitLittleEndian2Float(pcm, 0, rawData, 0, 320/2);
                final byte encoded[]=encode(rawData);

                Thread t = new Thread(new Runnable() {
                    public void run() {
                        DatagramPacket p = new DatagramPacket(encoded, encoded.length, serverIPAddress, 5010);
                        try {
                            udpSocket.send(p);
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    };
                });
                t.start();
            }

The problem is that the send method of the udpSocket can't be called on the UI thread otherwise an exception is thrown. These notifications arrive once every 20ms, and I'd like to send the data through udp as soon as they're available but I think it's a waste of resources to create a new Thread every time. How can I manage to call the send method on a worker thread that I've previously created?

Answer 1

Create a secondary thread and post task to it using handler.Refer code below:

public class MainActivity extends Activity {
TextView txt;
// our handler
 Handler handler = new Handler() {
  @Override
  public void handleMessage(Message msg) {
//display each item in a single line
  txt.setText(txt.getText()+"Item "+System.getProperty("line.separator"));
     }
 };

 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  txt=(TextView)findViewById(R.id.txt);
 }

 @Override
 protected void onStart() {
  super.onStart();
              // create a new thread
  Thread background=new Thread(new Runnable() {

   @Override
   public void run() {
    for(int i=0;i<10;i++)
    {
     try {
      Thread.sleep(1000);        b.putString("My Key", "My Value: 

"+String.valueOf(i));
// send message to the handler with the current message handler          

handler.sendMessage(handler.obtainMessage());
     } catch (Exception e) {
      Log.v("Error", e.toString());
     }
    }
   }
  });

  background.start();
 }
}

refer this for more info

Answer 2

You can left only one Thread using BlockingQueue. Lock at this example.