Java-Gaming.org Hi !
Featured games (83)
games approved by the League of Dukes
Games in Showcase (513)
Games in Android Showcase (120)
games submitted by our members
Games in WIP (577)
games currently in development
News: Read the Java Gaming Resources, or peek at the official Java tutorials
 
    Home     Help   Search   Login   Register   
Pages: [1]
  ignore  |  Print  
  UDP Network code, packet data ends up empty but still sends?  (Read 1016 times)
0 Members and 1 Guest are viewing this topic.
Offline chumpkingdom

Junior Newbie





« Posted 2013-04-30 06:17:10 »

This is my client code:

1  
2  
3  
4  
5  
6  
7  
8  
9  
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
32  
33  
34  
35  
36  
37  
38  
39  
40  
41  
42  
43  
44  
45  
46  
47  
48  
49  
50  
51  
52  
53  
54  
package Client;

import java.io.IOException;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;

public class ClientTest
{
   protected DatagramChannel channel;
   protected SocketAddress serverAddress;
   protected DatagramSocket socket;
   protected Selector selector;
   protected ByteBuffer packetBuffer;
   
   
   public static void main(String[] args) throws IOException
   {
      new ClientTest();
   }
   
   public ClientTest() throws IOException
   {
      serverAddress  = new InetSocketAddress("localhost", 4445);
      packetBuffer = ByteBuffer.allocate(256);
      selector = Selector.open();
      channel = DatagramChannel.open();
      channel.configureBlocking(false);
     
      SelectionKey key = channel.register(selector, SelectionKey.OP_READ);
      socket = channel.socket();
     
      channel.connect(serverAddress);
     
      packetBuffer.flip();
      String packetData = "Test data!";
      byte[] pByte = packetData.getBytes();
      packetBuffer.rewind();
      packetBuffer.put(pByte);
     
      byte[] buf = new byte[packetBuffer.remaining()];
      packetBuffer.get(buf);
      String s = new String(buf);
      System.out.println("Sent: " + s);
     
      channel.write(packetBuffer);
     
     
   }
}


Server:

1  
2  
3  
4  
5  
6  
7  
8  
9  
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
32  
33  
34  
35  
36  
37  
38  
39  
40  
41  
42  
43  
44  
45  
46  
47  
48  
49  
50  
51  
52  
53  
54  
55  
56  
package Server;

import java.io.IOException;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;

import Server.ServerTest;

public class ServerTest
{
   protected DatagramChannel channel;
   protected DatagramSocket socket;
   protected Selector selector;
   protected ByteBuffer packetBuffer;
   protected boolean running;
   protected SocketAddress clientAddress;
   protected InetSocketAddress iAddress;
   
   public static void main(String[] args) throws IOException
   {
      new ServerTest();
   }
   
   public ServerTest() throws IOException
   {
      running = true;
      packetBuffer = ByteBuffer.allocate(256);
      selector = Selector.open();
      channel = DatagramChannel.open();
      channel.configureBlocking(false);
      iAddress = new InetSocketAddress(4445);
      channel.bind(iAddress);
     
      SelectionKey key = channel.register(selector, SelectionKey.OP_READ);
      socket = channel.socket();
     
      while(running)
      {
         if(selector.selectNow() > 0)
         {
            clientAddress = channel.receive(packetBuffer);
            packetBuffer.flip();
            byte[] bytes = new byte[packetBuffer.remaining()];
            packetBuffer.get(bytes);
            String s = new String(bytes);
            System.out.println("Client: " + s);
         }
      }
     
   }
}


The packet gets sent from the client to the server, but it doesn't seem to send anything but blank spaces, I'm not sure if i'm incorrectly writing information to the buffer, or whether i'm not getting the information from the buffer correctly?
Can someone please give me some insight as to where my code is going wrong?
Signing out, King Chumpanator the great!
Offline Riven
« League of Dukes »

JGO Overlord


Medals: 817
Projects: 4
Exp: 16 years


Hand over your head.


« Reply #1 - Posted 2013-04-30 07:11:50 »

1  
2  
3  
4  
5  
6  
7  
8  
-   packetBuffer.flip();
...
-   packetBuffer.rewind();
-   packetBuffer.put(pByte);

+   packetBuffer.clear();
+   packetBuffer.put(pByte);
+   packetBuffer.flip();


You probably want to look at the javadoc of java.nio.Buffer, to get a good grasp on these 'confusingly' named operations, like clear (which doesn't clear data), flip (which doesn't flip data) and rewind (which doesn't rewind data). Pointing

It's all about signalling where the 'interesting data' is, in the buffer (between position and limit).

Hi, appreciate more people! Σ ♥ = ¾
Learn how to award medals... and work your way up the social rankings
Offline chumpkingdom

Junior Newbie





« Reply #2 - Posted 2013-04-30 07:18:12 »

Thanks for the help champ Smiley You saved millenias of my life.
Signing out, King Chumpanator the pinnacle!
Games published by our own members! Check 'em out!
Legends of Yore - The Casual Retro Roguelike
Offline Jimmt
« League of Dukes »

JGO Kernel


Medals: 136
Projects: 4
Exp: 3 years



« Reply #3 - Posted 2013-04-30 16:57:25 »

King Chumpanator the pinnacle
O.o
Pages: [1]
  ignore  |  Print  
 
 
You cannot reply to this message, because it is very, very old.

 

Add your game by posting it in the WIP section,
or publish it in Showcase.

The first screenshot will be displayed as a thumbnail.

Longarmx (52 views)
2014-10-17 03:59:02

Norakomi (43 views)
2014-10-16 15:22:06

Norakomi (33 views)
2014-10-16 15:20:20

lcass (37 views)
2014-10-15 16:18:58

TehJavaDev (68 views)
2014-10-14 00:39:48

TehJavaDev (67 views)
2014-10-14 00:35:47

TehJavaDev (60 views)
2014-10-14 00:32:37

BurntPizza (73 views)
2014-10-11 23:24:42

BurntPizza (45 views)
2014-10-11 23:10:45

BurntPizza (86 views)
2014-10-11 22:30:10
Understanding relations between setOrigin, setScale and setPosition in libGdx
by mbabuskov
2014-10-09 22:35:00

Definite guide to supporting multiple device resolutions on Android (2014)
by mbabuskov
2014-10-02 22:36:02

List of Learning Resources
by Longor1996
2014-08-16 10:40:00

List of Learning Resources
by SilverTiger
2014-08-05 19:33:27

Resources for WIP games
by CogWheelz
2014-08-01 16:20:17

Resources for WIP games
by CogWheelz
2014-08-01 16:19:50

List of Learning Resources
by SilverTiger
2014-07-31 16:29:50

List of Learning Resources
by SilverTiger
2014-07-31 16:26:06
java-gaming.org is not responsible for the content posted by its members, including references to external websites, and other references that may or may not have a relation with our primarily gaming and game production oriented community. inquiries and complaints can be sent via email to the info‑account of the company managing the website of java‑gaming.org
Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines | Managed by Enhanced Four Valid XHTML 1.0! Valid CSS!