I use the following code to receive the data from a particular port. It's not working in Android. But sending data to particular port is working fine.
public class UDPDemo extends Activity {
private TextView tv;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
tv = (TextView)findViewById(R.id.recv_message);
try {
DatagramSocket clientsocket=new DatagramSocket(9876);
byte[] receivedata = new byte[1024];
while(true)
{
DatagramPacket recv_packet = new DatagramPacket(receivedata, receivedata.length);
Log.d("UDP", "S: Receiving...");
clientsocket.receive(recv_packet);
String rec_str = new String(recv_packet.getData());
tv.setText(rec_str);
Log.d(" Received String ",rec_str);
InetAddress ipaddress = recv_packet.getAddress();
int port = recv_packet.getPort();
Log.d("IPAddress : ",ipaddress.toString());
Log.d(" Port : ",Integer.toString(port));
}
} catch (Exception e) {
Log.e("UDP", "S: Error", e);
}
}
}
If you are using the emulator you may need setup redirects , remember the emulator is behind a virtual router.
In other words, type these commands in;
telnet localhost 5554
redir add udp:9876:9876
and try again.
Create Datagram packet
try {
mDataGramSocket = new DatagramSocket(Config.PORT_NUMBER);
mDataGramSocket.setReuseAddress(true);
mDataGramSocket.setSoTimeout(1000);
} catch (SocketException e) {
e.printStackTrace();
}
Call below function through AsyncTask
Create Function to receive infinitely
public void receive() {
String text;
byte[] message = new byte[1500];
DatagramPacket p = new DatagramPacket(message, message.length);
try {
while (true) { // && counter < 100 TODO
// send to server omitted
try {
mDataGramSocket.receive(p);
text = new String(message, 0, p.getLength());
// If you're not using an infinite loop:
//mDataGramSocket.close();
} catch (SocketTimeoutException | NullPointerException e) {
// no response received after 1 second. continue sending
e.printStackTrace();
}
}
} catch (Exception e) {
e.printStackTrace();
// return "error:" + e.getMessage();
mReceiveTask.publish("error:" + e.getMessage());
}
// return "out";
}
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