From fb7b6bba4261b64e463a18a875cd3ce19d553665 Mon Sep 17 00:00:00 2001
From: "Norbraten, Terry" <tdnorbra@nps.edu>
Date: Tue, 28 Jul 2020 15:43:15 -0700
Subject: [PATCH] improved looping constructs
---
.../MulticastSender.java | 18 ++++++-------
.../UdpMulticastHttpExamples/UdpReceiver.java | 27 ++++++++-----------
.../UdpMulticastHttpExamples/UdpSender.java | 14 +++++-----
3 files changed, 27 insertions(+), 32 deletions(-)
diff --git a/examples/src/UdpMulticastHttpExamples/MulticastSender.java b/examples/src/UdpMulticastHttpExamples/MulticastSender.java
index 7aaa9e4761..584f01d568 100644
--- a/examples/src/UdpMulticastHttpExamples/MulticastSender.java
+++ b/examples/src/UdpMulticastHttpExamples/MulticastSender.java
@@ -61,8 +61,8 @@ public class MulticastSender {
multicastSocket.joinGroup(group, DisThreadedNetIF.findIpv4Interface());
// You can join multiple groups here
- DatagramPacket packet;
- byte[] buffer;
+ byte[] buffer = baos.toByteArray();
+ DatagramPacket packet = new DatagramPacket(buffer, buffer.length, multicastAddress, DESTINATION_PORT);
for (int index = 0; index < LOOPSIZE; index++)
{
@@ -70,17 +70,16 @@ public class MulticastSender {
if (index < LOOPSIZE - 1)
{
// Put together an updated packet to send
- dos.writeChars(System.getProperty("user.name") + ": ");
+ dos.writeChars("From " + System.getProperty("user.name") + ": ");
dos.writeChars("MulticastSender packet " + Integer.toString(index) + ";"); // string chars for readability
dos.writeInt (index); // arbitrary data, needs Java or byte-alignment to read
dos.writeFloat(17.0f); // arbitrary data, needs Java or byte-alignment to read
dos.writeFloat(23.0f); // arbitrary data, needs Java or byte-alignment to read
}
else dos.writeChars(QUIT_SENTINEL + ";"); // note string must include ; semicolon as termination sentinel
-
+
buffer = baos.toByteArray();
- packet = new DatagramPacket(buffer, buffer.length, multicastAddress, DESTINATION_PORT);
-
+ packet.setData(buffer);
multicastSocket.send(packet);
System.out.println("Sent multicast packet " + index + " of " + LOOPSIZE);
baos.reset();
@@ -96,13 +95,14 @@ public class MulticastSender {
}
catch(IOException | InterruptedException e)
{
+ System.err.println("Problem with MulticastSender, see exception trace:");
+ System.err.println(e);
+ } finally {
+
if (multicastSocket != null)
multicastSocket.close();
dos.close();
-
- System.err.println("Problem with MulticastSender, see exception trace:");
- System.err.println(e);
}
}
diff --git a/examples/src/UdpMulticastHttpExamples/UdpReceiver.java b/examples/src/UdpMulticastHttpExamples/UdpReceiver.java
index 5b23f76d15..829e2c19e3 100644
--- a/examples/src/UdpMulticastHttpExamples/UdpReceiver.java
+++ b/examples/src/UdpMulticastHttpExamples/UdpReceiver.java
@@ -2,6 +2,7 @@ package UdpMulticastHttpExamples;
import java.io.*;
import java.net.*;
+import java.nio.ByteBuffer;
/**
* An example of receiving UDP packets. Since very often both the
@@ -26,7 +27,6 @@ public class UdpReceiver
public static void main(String[] args) throws IOException
{
DatagramSocket udpSocket = null;
- DataInputStream dis = null;
int packetCount = 0;
try
@@ -38,10 +38,9 @@ public class UdpReceiver
udpSocket.setReceiveBufferSize(1500);
udpSocket.setBroadcast(false); // we're just receiving here
- byte[] receiveBuffer = new byte[udpSocket.getReceiveBufferSize()];
- DatagramPacket receivePacket = new DatagramPacket(receiveBuffer, receiveBuffer.length);
+ ByteBuffer buffer = ByteBuffer.allocate(1500);
+ DatagramPacket receivePacket = new DatagramPacket(buffer.array(), buffer.capacity());
- InputStream bais;
float first, second;
// You need a new receiving packet to read from every packet received
@@ -49,27 +48,23 @@ public class UdpReceiver
{
udpSocket.receive(receivePacket);
- // Decode the contents by extracting the data from the packet
- bais = new ByteArrayInputStream(receivePacket.getData());
- dis = new DataInputStream(bais);
-
// What happens if you read an integer? Two double values? ***
- first = dis.readFloat(); // alternatives: readFloat(); readInt(); dis.readUTF();
- second = dis.readFloat();
+ first = buffer.getFloat(); // alternatives: readFloat(); readInt(); dis.readUTF();
+ second = buffer.getFloat();
+
+ buffer.clear();
System.out.println("first value: " + first + " second value: " + second + " packet count = " + ++packetCount);
}
}
catch(IOException e)
{
- if (udpSocket != null)
- udpSocket.close();
-
- if (dis != null)
- dis.close();
-
System.err.println("Problem with UdpReceiver, see exception trace:");
System.err.println(e);
+ } finally {
+
+ if (udpSocket != null)
+ udpSocket.close();
}
}
}
diff --git a/examples/src/UdpMulticastHttpExamples/UdpSender.java b/examples/src/UdpMulticastHttpExamples/UdpSender.java
index 66ca17a994..d40a56cd97 100644
--- a/examples/src/UdpMulticastHttpExamples/UdpSender.java
+++ b/examples/src/UdpMulticastHttpExamples/UdpSender.java
@@ -16,7 +16,7 @@ import java.net.*;
*/
public class UdpSender
{
- public static final String MY_NAME = "(default name)";
+ public static final String MY_NAME = System.getProperty("user.name");
public static final int SENDING_PORT = 1414;
public static final int RECEIVING_PORT = 1415;
public static final String DESTINATION_HOST = "localhost";
@@ -38,7 +38,7 @@ public class UdpSender
// is a java.io utility that lets us put together an array of binary
// data, which we put into the UDP packet.
- ByteArrayOutputStream baos = new ByteArrayOutputStream();
+ ByteArrayOutputStream baos = new ByteArrayOutputStream(1500);
dos = new DataOutputStream(baos);
// alternatives: writeFloat(17.0f); writeInt(17); writeUTF("\"hello MV3500 no really\"");
@@ -53,7 +53,7 @@ public class UdpSender
// ID of the host we are sending from
InetAddress sourceAddress = InetAddress.getByName("localhost"); // possibly identical if source not modified
- DatagramPacket packet = new DatagramPacket(buffer, buffer.length, destinationAddress, RECEIVING_PORT );
+ DatagramPacket packet = new DatagramPacket(buffer, buffer.length, destinationAddress, RECEIVING_PORT);
// How fast does this go? Does UDP try to slow it down, or does
// this cause network problems? (hint: yes for an unlimited send
@@ -65,20 +65,20 @@ public class UdpSender
{
udpSocket.send(packet);
Thread.sleep(1000); // Send 100, one per second
- System.out.println(MY_NAME + " " + sourceAddress + " sent packet " + index + " of 100");
+ System.out.println(MY_NAME + ": " + sourceAddress + " sent packet " + index + " of 100");
}
System.out.println("UdpSender complete.");
}
catch (IOException | InterruptedException e)
{
+ System.err.println("Problem with UdpSender, see exception trace:");
+ System.err.println(e);
+ } finally {
if (udpSocket != null)
udpSocket.close();
if (dos != null)
dos.close();
-
- System.err.println("Problem with UdpSender, see exception trace:");
- System.err.println(e);
}
}
}
--
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