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chargen.javaAPI DocApache Commons NET 1.4.1 API4586Sat Dec 03 10:05:48 GMT 2005examples

chargen

public final class chargen extends Object
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]

Fields Summary
Constructors Summary
Methods Summary
public static final voidchargenTCP(java.lang.String host)

        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 voidchargenUDP(java.lang.String host)

        int packets = 50;
        byte[] data;
        InetAddress address;
        CharGenUDPClient client;

        address = InetAddress.getByName(host);
        client = new CharGenUDPClient();

        client.open();
        // 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 voidmain(java.lang.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] <hostname>");
            System.exit(1);
        }