studentdemo.java

Java p2p程序设计2002年版

package com.sams.jxta.groups.student;

import net.jxta.discovery.DiscoveryEvent;
import net.jxta.discovery.DiscoveryListener;
import net.jxta.discovery.DiscoveryService;
import net.jxta.document.Advertisement;
import net.jxta.document.AdvertisementFactory;
import net.jxta.document.MimeMediaType;
import net.jxta.document.StructuredDocument;
import net.jxta.document.TextElement;
import net.jxta.exception.PeerGroupException;
import net.jxta.exception.ProtocolNotSupportedException;
import net.jxta.id.ID;
import net.jxta.id.IDFactory;
import net.jxta.impl.document.PlainTextDocument;
import net.jxta.impl.peergroup.StdPeerGroup;
import net.jxta.peergroup.PeerGroup;
import net.jxta.peergroup.PeerGroupFactory;
import net.jxta.platform.Module;
import net.jxta.platform.ModuleClassID;
import net.jxta.platform.ModuleSpecID;
import net.jxta.protocol.DiscoveryResponseMsg;
import net.jxta.protocol.ModuleImplAdvertisement;
import net.jxta.protocol.PeerGroupAdvertisement;
import net.jxta.protocol.PeerAdvertisement;
import net.jxta.impl.peergroup.Platform;
import net.jxta.impl.peergroup.GenericPeerGroup;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.util.Enumeration;
import java.net.*;
import java.io.IOException;
import com.sams.jxta.groups.*;

/**
 * This class demonstrates how to use the Group Manager.
 * 
 */
 
public class StudentDemo implements Module{

    private static final org.apache.log4j.Category LOG = 
        org.apache.log4j.Category.getInstance(StudentDemo.class.getName());
    protected PeerGroup netPeerGroup = null;
    /**
     * we need to understand jxta protocols. This is used if you use "Java Web Start"
     * or if you launch via a non-forked JVM in NetBeans or other IDE.
     */
    static {
        URL.setURLStreamHandlerFactory( new URLStreamHandlerFactory() {
            public URLStreamHandler createURLStreamHandler(
            String protocol ) {
                if( "urn".equals( protocol ) ||
                "jxta".equals( protocol )) {
                    return new URLStreamHandler() {
                        protected URLConnection openConnection(
                        URL u )
                        throws IOException {
                            return null;
                        }
                    };
                }
                else
                    return null;
            }
        } );
    }
    /*
     * The main method which serves as the entry point
     */
     
    public static void main(String args[]){
        
        StudentDemo sample = new StudentDemo();
        sample.runJXTA();
    }

    /*
     * This method starts the JXTA platform.
     *  
     */
     
    private void runJXTA(){
    
        
        // Get an instance of the net peer group
        try {
        
            netPeerGroup = PeerGroupFactory.newNetPeerGroup();
        } catch (PeerGroupException peerGroupException) {
            //could not instanciate the group, print the stack and exit
            LOG.error("Group Creation Failure !",peerGroupException);
            System.exit(1);
        }
        // Create a module impl advertisement by using the factory.
        // Set the appropriate fields.
        ModuleClassID mID = IDFactory.newModuleClassID(); 
        ModuleSpecID moduleSpecID = PeerGroup.refMembershipSpecID;
        ModuleImplAdvertisement adv = (ModuleImplAdvertisement)
            AdvertisementFactory.newAdvertisement(ModuleImplAdvertisement.getAdvertisementType());
        adv.setModuleSpecID(moduleSpecID);
        adv.setCompat(StdPeerGroup.stdCompatStatement);
        adv.setCode("com.sams.jxta.groups.student.StudentDemo");
        adv.setUri("http://www.jxta.org/download/jxta.jar");        
        // This module is loaded by the net peer group.
        try{
            netPeerGroup.loadModule(mID,adv);
        } catch (ProtocolNotSupportedException protocolException) {
            LOG.error("Could not load Module !",protocolException);
            System.exit(1);
        } catch (PeerGroupException peerGroupException) {
            LOG.error("Could not load Module !",peerGroupException);
            System.exit(1);
        }
    }            

    /*
     * This method is called when the module is initialized.
     * This is when we use the Group Manager.
     */
    public void init(PeerGroup parentGroup,ID assignedID,Advertisement implAdv)
                                 throws PeerGroupException{
                                 
        GroupManager manager = new GroupManager(parentGroup/*netPeerGroup*/,parentGroup);
        // This is to create a new University Admissions group
        // to deal with the admissions of a particular university
        PeerGroup p =manager.addGroup("UniversityStudents",
                                      "com.sams.jxta.groups.student.UniversityAdmissionsService",
                                      "To represent all graduate students in a University",null,false);
             
        System.out.println("Successfully created Admissions Service");
        
        // We try to submit a Pre-Application(Pre App) Form and join. 
        // Initially we try to join the department of management
        
        try{
        
            StructuredDocument preAppForm = 
                PreApplicationForm.createPreAppForm(PreApplicationForm.DEPARTMENT_MANAGEMENT);
            manager.joinGroup(p,preAppForm,"PreApplication");
            
        } catch(GroupManagerAuthenticationException authenticationException) {
        
           LOG.debug("Exception :Expected behavior. University has no admissions for this dpt");
           LOG.debug("Message is : "+authenticationException.getMessage());    
        } catch(ProtocolNotSupportedException protocolException) {
        
           LOG.error("Error in join !",protocolException);
        }

        // Try to submit a Pre-Application for the Department of computer science
        // Must be success !
        // Applications will be accepted if GPA >3 and name != null

        try{
        
            StructuredDocument preAppForm = 
                PreApplicationForm.createPreAppForm(PreApplicationForm.DEPARTMENT_COMPUTER_SCIENCE);
            manager.joinGroup(p,preAppForm,"PreApplication");
            
        } catch(GroupManagerAuthenticationException authenticationException) {
            LOG.error("Error in join !",authenticationException);
        } catch(ProtocolNotSupportedException protocolException) {
            LOG.error("Error in join !",protocolException);
        }
    }
    

    /*
     * Methods to be implemented by virtue of being a module.
     * Not used in this example 
     */
    public int startApp(String[] args){return 0;}
    public void stopApp(){};
    
}