Sends the specified text or file as a datagram to the specified port of the specified host
/*
* Copyright (c) 2004 David Flanagan. All rights reserved.
* This code is from the book Java Examples in a Nutshell, 3nd Edition.
* It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
* You may study, use, and modify it for any non-commercial purpose,
* including teaching and use in open-source projects.
* You may distribute it non-commercially as long as you retain this notice.
* For a commercial use license, or to purchase the book,
* please visit http://www.davidflanagan.com/javaexamples3.
*/
//package je3.net;
import java.io.File;
import java.io.FileInputStream;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
/**
* This class sends the specified text or file as a datagram to the specified
* port of the specified host.
*/
public class UDPSend {
public static final String usage = "Usage: java UDPSend <hostname> <port> <msg>...\n"
+ " or: java UDPSend <hostname> <port> -f <file>";
public static void main(String args[]) {
try {
// Check the number of arguments
if (args.length < 3)
throw new IllegalArgumentException("Wrong number of args");
// Parse the arguments
String host = args[0];
int port = Integer.parseInt(args[1]);
// Figure out the message to send.
// If the third argument is -f, then send the contents of the file
// specified as the fourth argument. Otherwise, concatenate the
// third and all remaining arguments and send that.
byte[] message;
if (args[2].equals("-f")) {
File f = new File(args[3]);
int len = (int) f.length(); // figure out how big the file is
message = new byte[len]; // create a buffer big enough
FileInputStream in = new FileInputStream(f);
int bytes_read = 0, n;
do { // loop until we've read it all
n = in.read(message, bytes_read, len - bytes_read);
bytes_read += n;
} while ((bytes_read < len) && (n != -1));
} else { // Otherwise, just combine all the remaining arguments.
String msg = args[2];
for (int i = 3; i < args.length; i++)
msg += " " + args[i];
// Convert the message to bytes using UTF-8 encoding
message = msg.getBytes("UTF-8");
}
// Get the internet address of the specified host
InetAddress address = InetAddress.getByName(host);
// Initialize a datagram packet with data and address
DatagramPacket packet = new DatagramPacket(message, message.length, address, port);
// Create a datagram socket, send the packet through it, close it.
DatagramSocket dsocket = new DatagramSocket();
dsocket.send(packet);
dsocket.close();
} catch (Exception e) {
System.err.println(e);
System.err.println(usage);
}
}
}
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