怎么样用java类(dnsjava包)来实现ping方法

Question

import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.DatagramPacket;
import java.io.IOException;public class MyPing
{
    static final int echoPort = 7;
    static final int maxPingTime = 3000;     // Milliseconds
    static final int pingPollInterval = 100; // Milliseconds    public void ping(InetAddress dest)
    {
        String message = "test ping";
        byte[] outmsg = message.getBytes();
        int length = message.getBytes().length;
        byte[] inmsg = new byte[length];
        DatagramPacket outPacket = new DatagramPacket(outmsg, length);
        DatagramPacket inPacket = new DatagramPacket(inmsg, length);        try
        {
            DatagramSocket socket = new DatagramSocket(echoPort, dest);
            outPacket.setAddress(dest);
            outPacket.setPort(echoPort);
            socket.send(outPacket);
            socket.setSoTimeout(5000);
            socket.receive(inPacket);
            System.out.println(new String(inmsg));
        }
        catch (SocketException e)
        {
            e.printStackTrace();
        }
        catch (IOException e)
        {
            e.printStackTrace(); 
        }    }
}
import java.net.InetAddress;
import java.net.UnknownHostException;class Tester
{
    public static void main(String[] a)
    {
        try
        {
            InetAddress addr = InetAddress.getLocalHost();
            new MyPing().ping(addr);
        }
        catch (UnknownHostException e)
        {
            e.printStackTrace();
        }
    }
}