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What this is

This file is included in the "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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The source code

 * Copyright 2001-2004 The Apache Software Foundation
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.
package examples;


 * This is an example program demonstrating how to use the CharGenTCPClient
 * and CharGenUDPClient classes.  This program connects to the default
 * chargen service port of a specified server, then reads 100 lines from
 * of generated output, writing each line to standard output, and then
 * closes the connection.  The UDP invocation of the program sends 50
 * datagrams, printing the reply to each.
 * The default is to use the TCP port.  Use the -udp flag to use the UDP
 * port.

* Usage: chargen [-udp] *

***/ public final class chargen { public static final void chargenTCP(String host) throws IOException { int lines = 100; String line; CharGenTCPClient client = new CharGenTCPClient(); BufferedReader chargenInput; // We want to timeout if a response takes longer than 60 seconds client.setDefaultTimeout(60000); client.connect(host); chargenInput = new BufferedReader(new InputStreamReader(client.getInputStream())); // We assume the chargen service outputs lines, but it really doesn't // have to, so this code might actually not work if no newlines are // present. while (lines-- > 0) { if ((line = chargenInput.readLine()) == null) break; System.out.println(line); } client.disconnect(); } public static final void chargenUDP(String host) throws IOException { int packets = 50; byte[] data; InetAddress address; CharGenUDPClient client; address = InetAddress.getByName(host); client = new CharGenUDPClient();; // If we don't receive a return packet within 5 seconds, assume // the packet is lost. client.setSoTimeout(5000); while (packets-- > 0) { client.send(address); try { data = client.receive(); } // Here we catch both SocketException and InterruptedIOException, // because even though the JDK 1.1 docs claim that // InterruptedIOException is thrown on a timeout, it seems // SocketException is also thrown. catch (SocketException e) { // We timed out and assume the packet is lost. System.err.println("SocketException: Timed out and dropped packet"); continue; } catch (InterruptedIOException e) { // We timed out and assume the packet is lost. System.err.println( "InterruptedIOException: Timed out and dropped packet"); continue; } System.out.write(data); System.out.flush(); } client.close(); } public static final void main(String[] args) { if (args.length == 1) { try { chargenTCP(args[0]); } catch (IOException e) { e.printStackTrace(); System.exit(1); } } else if (args.length == 2 && args[0].equals("-udp")) { try { chargenUDP(args[1]); } catch (IOException e) { e.printStackTrace(); System.exit(1); } } else { System.err.println("Usage: chargen [-udp] "); System.exit(1); } } }

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