From a394deea7819f90c2c58eba2c94aa2bfa8111182 Mon Sep 17 00:00:00 2001
From: brutzman <brutzman@nps.edu>
Date: Sun, 25 Aug 2024 18:39:20 -0700
Subject: [PATCH] updates to support compatible chat client using Java console
and keyboard to provide messages, using MulticastUdpChatKeyboardSender
---
.../src/UdpExamples/MulticastUdpReceiver.java | 73 +++++++++++++------
1 file changed, 51 insertions(+), 22 deletions(-)
diff --git a/examples/src/UdpExamples/MulticastUdpReceiver.java b/examples/src/UdpExamples/MulticastUdpReceiver.java
index 86e3e6dfdd..83b5c415e9 100644
--- a/examples/src/UdpExamples/MulticastUdpReceiver.java
+++ b/examples/src/UdpExamples/MulticastUdpReceiver.java
@@ -1,5 +1,6 @@
package UdpExamples;
+import static UdpExamples.MulticastUdpChatKeyboardSender.LINE_TERMINATOR;
import edu.nps.moves.dis7.utilities.DisThreadedNetworkInterface;
import java.io.*;
import java.net.*;
@@ -38,6 +39,8 @@ public class MulticastUdpReceiver
private static final boolean INFINITE_READ_LOOP = true;
private static NetworkInterface ni;
+
+ public static final int BUFFER_LENGTH = 1500;
/**
* Program invocation, execution starts here
@@ -47,7 +50,7 @@ public class MulticastUdpReceiver
{
MulticastSocket multicastSocket = null;
InetSocketAddress group = null;
- ByteBuffer buffer = ByteBuffer.allocate(1500);
+ ByteBuffer buffer = ByteBuffer.allocate(BUFFER_LENGTH);
DatagramPacket packet = new DatagramPacket(buffer.array(), buffer.capacity());
try {
@@ -67,49 +70,75 @@ public class MulticastUdpReceiver
group = new InetSocketAddress(multicastAddress, DESTINATION_PORT);
// Join group useful on receiving side
- multicastSocket.joinGroup(group, ni = DisThreadedNetworkInterface.findIpv4Interface());
+ multicastSocket.joinGroup(group, ni = DisThreadedNetworkInterface.findIpv4Interface()); // utility function
// You can join multiple groups here
- System.out.println("Multicast address/port: " + multicastAddress.getHostAddress() + "/" + DESTINATION_PORT);
+ System.out.println("Multicast address/port: " + multicastAddress.getHostAddress() + "/" + DESTINATION_PORT +
+ " isBound=" + multicastSocket.isBound());
+ // unnecessary, no server involved: + "isConnected=" + multicastSocket.isConnected()
System.out.println("Multicast packets received log:");
- int index, count = 0; // initialize
- float firstFloat, secondFloat;
+ int messageCount = 0; // initialize
StringBuilder firstCharacters = new StringBuilder();
char nextChar;
- while (true) { // true is always true, so this is an infinite loop that continues until interrupted
- multicastSocket.receive(packet);
- count++;
+ while (true) // true is always true, so this is an infinite loop that continues until interrupted
+ {
+ // initializations for this loop
+ int messageIndex = 0;
+ float firstFloat = 0.0f;
+ float secondFloat = 0.0f;
+
+ multicastSocket.receive(packet); // this method call will block until a packet is received
+ messageCount++;
- nextChar = ' ';
+ nextChar = ' '; // reinitialize
while (nextChar != ';') // read and build string until terminator ; found
{
nextChar = buffer.getChar();
firstCharacters.append(nextChar);
}
- if (firstCharacters.toString().contains(MulticastUdpSender.QUIT_SENTINEL)) {
+ if (firstCharacters.toString().contains(MulticastUdpSender.QUIT_SENTINEL))
+ {
System.out.println("Received sentinel \"" + MulticastUdpSender.QUIT_SENTINEL + "\"");
if (!INFINITE_READ_LOOP) {
break; // exit out of reading loop
}
}
- index = buffer.getInt();
- firstFloat = buffer.getFloat();
- secondFloat = buffer.getFloat();
+ boolean foundNumbers = false;
+ String line = firstCharacters.toString();
+ if (line.contains(LINE_TERMINATOR))
+ {
+ foundNumbers = false;
+ firstCharacters.setLength(line.length() - LINE_TERMINATOR.length()); // clip EOL sentinel
+ }
+ else if (buffer.hasRemaining()) // likely always true since size is 1500
+ {
+ messageIndex = buffer.getInt();
+ firstFloat = buffer.getFloat();
+ secondFloat = buffer.getFloat();
+ // simplistic tests for numbers read from buffer
+ if ((messageIndex == 0) && (firstFloat == 0.0f) && (secondFloat == 0.0f))
+ foundNumbers = false;
+ else if ((messageIndex >= 0) && (messageIndex <= 10000))
+ foundNumbers = true;
+ }
+ else System.out.print("[trace] no numbers encountered in buffer");
buffer.clear();
- if (count < 10) {
- System.out.print(" "); // prettier output formatting
+ if (messageCount < 10) {
+ System.out.print(" "); // prettier output formatting for first nine lines
}
- System.out.print(count + ". \"" + firstCharacters + "\" "); // wrap string in quote marks
- System.out.println("index=" + index + ", firstFloat=" + firstFloat + " secondFloat=" + secondFloat);
-
- System.out.println("MulticastReceiver loop complete.");
- firstCharacters.setLength(0);
+ System.out.println(messageCount + ". \"" + firstCharacters + "\" "); // wrap string in quote marks
+ if (foundNumbers)
+ {
+ System.out.println(" messageIndex=" + messageIndex + ", firstFloat=" + firstFloat + " secondFloat=" + secondFloat);
+ System.out.println(" MulticastUdpReceiver message receipt complete.");
+ }
+ firstCharacters.setLength(0); // reset
}
} catch (IOException e) {
- System.err.println("Problem with MulticastReceiver, see exception trace:");
+ System.err.println("Problem with MulticastUdpReceiver, see exception trace:");
System.err.println(e);
} finally // clean up after exit condition
{
@@ -122,7 +151,7 @@ public class MulticastUdpReceiver
multicastSocket.close();
}
// socket/database/completion cleanup code can go here, if needed.
- System.out.println("MulticastReceiver finally block, complete.");
+ System.out.println("MulticastUdpReceiver finally block, complete.");
}
}
}
--
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