ping.java

Java p2p程序设计2002年版

package net.jxta.impl.shell.bin.ping;

import net.jxta.impl.shell.*;

import java.io.*;
import java.util.*;

import net.jxta.exception.*;
import net.jxta.discovery.*;
import net.jxta.endpoint.*;
import net.jxta.pipe.*;
import net.jxta.peergroup.*;
import net.jxta.document.*;
import net.jxta.id.*;
import net.jxta.protocol.*;
import java.util.*;

/**
 * The ping command class. This class essentially takes the input and coordinates
 * the execution of PingPeer.
 */
public class ping extends ShellApp  implements PingListener, PingReplyListener {
    
    private DiscoveryService discovery=null;
    
    private ShellEnv env = null;
    private static final int WaitingTime = 2000;
    private static final int  MAXRETRIES = 5;
    static ping pinger;
    PingPeer pingPeer;
    
    public ping() {
        pinger = this;
    }
    
    public static void println2(String str) {
        pinger.println(str);
    }
    
    public void stopApp() {
    }
        
    public int startApp(String[] args) {
        
        try {
            env = getEnv();
            discovery= group.getDiscoveryService();
            //flushAds();
            pingPeer = new PingPeer(discovery,group,env);
            
            // Notify me when certain events happen so I can respond
            // in my own way
            pingPeer.addPingReplyListener(this);
            pingPeer.addPingListener(this);
            
            if(args.length == 1 && "-listen".equals(args[0]))
                pingPeer.listen();
            else if(args.length == 1 && "-propagate".equals(args[0])) {
                println("Send propagate ping request...");
                pingPeer.propagate();
            } else if(args.length>0) {
                List list = (List)Arrays.asList(args);
                pingPeers(list);
            }
            else {
                help();
            }
            return 0;
        } catch (PingException e) {
            return 1;
        }
    }
    
    
    
    /**
     * This method takes the list of peers provided on command line
     * looks up their corresponding unicast ping pipes, and pings them. 
     */
    private void pingPeers(List names) {
        Iterator it = names.iterator();
        
        while(it.hasNext()) {
            String name = (String)it.next();
            println("Sending ping request to "+name+" ...");
            try {
                pingPeer.ping(name);
            } catch (PingException pe) {
                println("ping exception: "+name);
            }
        }
        
    }
    
    
    /**
     * Flush current cache of advertisements.
     */
    private void flushAds() {
        try {
            discovery.flushAdvertisements(null,DiscoveryService.ADV);
        } catch (IOException e) {
        }
    }
    
    /**
     * Callback invoked when a ping reply message
     * is received.
     * @param event The PingReplyEvent
     * @see PingReplyEvent
     * @see PingReplyHandler
     */
    public void pingReply(PingReplyEvent event) {
        long pdiff  =   event.getPriorDifferential(); // returns the first leg duration
        long diff   =   event.getDifferential(); // returns the second leg duration
        long tstamp =   event.getTimestamp(); // returns time event was received
        long ostamp =   event.getOriginTimestamp(); // returns time event was dispatched
        String pname =  event.getPeerName();
        println("");
        // display reply data.
        println(pname+": "+pdiff+"ms "+diff+"ms ");
    }
    
    /**
     * Callback invoked when a ping event occurs
     * @param event The PingEvent
     */
    public void pingEvent(PingEvent event) {
        println("");
        println("Pinged by "+event.getPeerName()+"....");
    }
    
    public String getDescription() {
        return "Send a ping request to another peer and receive a response if it is alive.";
    }

    public void help() {
        println("NAME");
        println("     ping  - Send a ping request to another peer and receive a response if it is alive.");
        println(" ");
        println("SYNOPSIS");
        println(" ");
        println("     ping [-listen] [-propagate] <peername>");
        println(" ");
        println("DESCRIPTION");
        println(" ");
        println("'ping' is a command that can be used to determine if remote");
        println("peers that are listening for pings are 'alive'.");
        println("Ping will recieve ping responses asynchronously and the times");
        println("involved in the ping messages are recoreded and displayed.");
        println(" ");
        println("EXAMPLE");
        println(" ");
        println("    JXTA> ping -listen");
        println("    JXTA> ping");
    }
    
    
}