由于版本的不同，書中的例子不能再Eclipse中正常運作。我們将例子改寫為：
RestoPeer.java:
import java.io.*;
import java.net.*;
import java.util.*;
import net.jxta.peergroup.PeerGroup;
import net.jxta.peergroup.NetPeerGroupFactory;
import net.jxta.peergroup.PeerGroupID;
import net.jxta.exception.PeerGroupException;
import net.jxta.discovery.DiscoveryService;
import net.jxta.id.IDFactory;
import net.jxta.pipe.PipeService;
import net.jxta.protocol.PeerGroupAdvertisement;
import net.jxta.protocol.ModuleImplAdvertisement;
// RestoPeer represents a restaurant that receives auction requests
// for food from HungryPeers. The RestoPeer will discover and join
// the RestoNet and publish itself as a provider for HungryPeers
public class RestoPeer {
private PeerGroup netpg = null; // The NetPeerGroup
private PeerGroup restoNet = null; // The RestoNet Peergroup
private String brand = "Chez JXTA"; // Brand of my restaurants
private int timeout = 3000; // Timeout; can be adjusted
// Services within the RestoNet peergroup
private DiscoveryService disco = null; // Discovery service
private PipeService pipes = null; // Pipe service
static String groupURL = "jxta:uuid-4d6172676572696e204272756e6f202002";
public static void main(String args[]) {
RestoPeer myapp = new RestoPeer();
myapp.startJxta();
System.exit(0);
}
// start the JXTA application
private void startJxta() {
try {
// Discover and join (or start) the default peergroup
netpg = (new NetPeerGroupFactory()).getWeakInterface();
} catch (PeerGroupException e) {
// Couldn't initialize; can't continue
System.out.println("Fatal error : creating the net PeerGroup");
System.exit(1);
}
// Discover (or create) and join the RestoNet peergroup
try {
joinRestoNet();
} catch (Exception e) {
System.out.println("Can't join or create RestoNet");
System.exit(1);
}
// Wait for HungryPeers
System.out.println("Waiting for HungryPeers");
while (true) {
// In later examples, HungryPeer requests are processed here
}
}
// Discover (or crete) and join the RestoNet peergroup
private void joinRestoNet() throws Exception {
int count = 3; // maximun number of attempts to discover
System.out.println("Attempting to Discover the RestoNet PeerGroup");
// Get the discovery service from the NetPeergroup
DiscoveryService hdisco = netpg.getDiscoveryService();
Enumeration ae = null; // Holds the discovered peers
// Loop until we discover the RestoNet or
// until we've exhausted the desired number of attempts
while (count-- > 0) {
try {
// search first in the peer local cache to find
// the RestoNet peergroup advertisement
ae = hdisco.getLocalAdvertisements(DiscoveryService.GROUP,
"Name", "RestoNet");
// If we found the RestoNet advertisement we are done
if ((ae != null) && ae.hasMoreElements())
break;
// If we did not find it, we send a discovery request
hdisco.getRemoteAdvertisements(null,
DiscoveryService.GROUP, "Name", "RestoNet", 1, null);
// Sleep to allow time for peers to respond to the
// discovery request
try {
Thread.sleep(timeout);
} catch (InterruptedException ie) {}
} catch (IOException e) {
// Found nothing! Move on.
}
}
PeerGroupAdvertisement restoNetAdv = null;
// Check if we found the RestoNet advertisement.
// If we didn't, then either
// we are the first peer to join or
// no other RestoNet peers are up.
// In either case, we must create the RestoNet peergroup
if (ae == null || !ae.hasMoreElements()) {
System.out.println(
"Could not find the RestoNet peergroup; creating one");
try {
// Create a new, all-purpose peergroup.
ModuleImplAdvertisement implAdv =
netpg.getAllPurposePeerGroupImplAdvertisement();
restoNet = netpg.newGroup(
mkGroupID(), // Assign new group ID
implAdv, // The implem. adv
"RestoNet", // Name of peergroup
"RestoNet, Inc.");// Description of peergroup
// Get the PeerGroup Advertisement
restoNetAdv = netpg.getPeerGroupAdvertisement();
} catch (Exception e) {
System.out.println("Error in creating RestoNet Peergroup");
throw e;
}
} else {
// The RestoNet advertisement was found in the cache;
// that means we can join the existing RestoNet peergroup
try {
restoNetAdv = (PeerGroupAdvertisement) ae.nextElement();
restoNet = netpg.newGroup(restoNetAdv);
System.out.println(
"Found the RestoNet Peergroup advertisement; joined existing group");
} catch (Exception e) {
System.out.println("Error in creating RestoNet PeerGroup from existing adv");
throw e;
}
}
try {
// Get the discovery and pipe services for the RestoNet Peergroup
disco = restoNet.getDiscoveryService();
pipes = restoNet.getPipeService();
} catch (Exception e) {
System.out.println("Error getting services from RestoNet");
throw e;
}
System.out.println("RestoNet Restaurant (" + brand + ") is on-line");
return;
}
private PeerGroupID mkGroupID() throws Exception {
return (PeerGroupID) IDFactory.fromURI( new URI ("urn" + ":" + groupURL));
}
}
HungryPeer,java
import java.io.*;
import java.util.Enumeration;
import java.util.Vector;
import net.jxta.peergroup.PeerGroup;
import net.jxta.peergroup.NetPeerGroupFactory;
import net.jxta.exception.PeerGroupException;
import net.jxta.document.AdvertisementFactory;
import net.jxta.document.Advertisement;
import net.jxta.discovery.DiscoveryService;
import net.jxta.pipe.PipeService;
import net.jxta.protocol.PeerGroupAdvertisement;
// HungryPeer tries to find a restaurant to
// get a good meal. It finds all RestoPeers in
// the RestoNet peergroup and (in later examples)
// requests bids from them.
public class HungryPeer {
private PeerGroup netpg = null; // NetPeergroup
private PeerGroup restoNet = null; // Resto Peergroup
private int timeout = 3000; // Timeout; can be adjusted
// Services within the RestoNet Peergroup
private DiscoveryService disco; // Discovery Service
private PipeService pipes; // Pipe Service
// Vector of discovered RestoPeers
private Vector restaurantAdvs = new Vector();
public static void main(String args[]) {
HungryPeer myapp = new HungryPeer();
myapp.startJxta();
System.exit(0);
}
// Start the JXTA application
private void startJxta() {
try {
// Discover (or create) and join the default jxta NetPeerGroup
netpg = (new NetPeerGroupFactory()).getWeakInterface();
} catch (PeerGroupException e) {
// Couldn't initialize; can't continue
System.out.println("Fatal error : creating the net PeerGroup");
System.exit(1);
}
// Discover and join the RestoNet Peergroup
// HungryPeers never create the RestoNet peergroup
try {
if (!joinRestoNet()) {
System.out.println("Sorry could not find the RestoNet Peergroup");
System.exit(2);
}
} catch (Exception e) {
System.out.println("Can't join RestoNet group");
System.exit(1);
}
}
// This method is used to discover the RestoNet Peergroup.
// If found the peer will join the peergroup
private boolean joinRestoNet() {
int count = 3; // maximum number of attempts to discover
System.out.println("Attempting to discover the RestoNet Peergroup");
// Get the Discovery service handle from the NetPeerGroup
DiscoveryService hdisco = netpg.getDiscoveryService();
// All discovered RestoNet Peers
Enumeration ae = null;
// Loop until we find the "RestoNet" Peergroup advertisement
// or we've exhausted the desired number of attempts
while (count-- > 0) {
try {
// Check if we have the advertisement in the local
// peer cache
ae = hdisco.getLocalAdvertisements(DiscoveryService.GROUP,
"Name", "RestoNet");
// If we found the RestoNet advertisement, we are done
if ((ae != null) && ae.hasMoreElements())
break;
// The RestoNet advertisement is not in the local
// cache . Send a discovery request to search for it.
hdisco.getRemoteAdvertisements(null,
DiscoveryService.GROUP, "Name", "RestoNet", 1, null);
// Wait to give peers a chance to respond
try {
Thread.sleep(timeout);
} catch (InterruptedException ie) {}
} catch (IOException e) {
// Found nothing! Move on.
}
}
// Check if we found the RestoNet advertisement
if (ae == null || !ae.hasMoreElements()) {
return false;
}
System.out.println("Found the RestoNet PeerGroup Advertisement");
// Get the advertisement
PeerGroupAdvertisement adv =
(PeerGroupAdvertisement) ae.nextElement();
try {
// Call the PeerGroup Factory to instantiate a new
// peergroup instance
restoNet = netpg.newGroup(adv);
} catch (Exception e) {
System.out.println("Could not create RestoPeerGroup");
return false;
}
try {
// Call the PeerGroup Factory to instantiate a new
// peergroup instance
restoNet = netpg.newGroup(adv);
// Get the Discovery and Pipe services to
// be used within the RestoNet Peergroup
disco = restoNet.getDiscoveryService();
pipes = restoNet.getPipeService();
} catch (Exception e) {
System.out.println("Could not create RestoPeerGroup");
return false;
}
System.out.println("The HungryPeer joined the restoNet PeerGroup");
return true;
}
}
主要的更改有：
1. 建立NetPeerGroup的方法和引用的頭檔案都改變了：netpg = (new NetPeerGroupFactory()).getWeakInterface();
2. Get ID 的fromURL函數更新為fromURI：return (PeerGroupID) IDFactory.fromURI( new URI ("urn" + ":" + groupURL));
測試成功。
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