synchronizingbean.java

这个范例程序演示了利用j2me技术开发无线服务器支持的应用。这是一个电影票订购程序

/*
 * Copyright 2001, 2002, 2003 Sun Microsystems, Inc. All Rights Reserved.
 * Except for any files in PNG format (which are marked with the filename
 * extension ".png"), GIF format (which are marked with the filename
 * extension ".gif"), or JPEG format (which are marked with the filename
 * extension ".jpg"), redistribution and use in source and binary forms,
 * with or without modification, are permitted provided that the
 * following conditions are met:
 * - Redistribution of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * - Redistribution in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * You may compile, use, perform and display the following files with
 * original Java Smart Ticket Sample Application code obtained from Sun
 * Microsystems, Inc. only:
 * - files in PNG format and having the ".png" extension
 * - files in GIF format and having the ".gif" extension
 * - files in JPEG format and having the ".jpg" extension
 * You may not modify or redistribute .png, .gif, or .jpg files in any
 * form, in whole or in part, by any means without prior written
 * authorization from Sun Microsystems, Inc. and its licensors, if any.
 * Neither the name of Sun Microsystems, Inc., the 'Java Smart Ticket
 * Sample Application', 'Java', 'Java'-based names, or the names of
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
 * MIDROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
 * ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
 * DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
 * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
 * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
 * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 * You acknowledge that this software is not designed, licensed or
 * intended for use in the design, construction, operation or maintenance
 * of any nuclear facility.
 * $Id: SynchronizingBean.java,v 1.10 2003/03/24 22:43:11 zull Exp $
 */
package com.sun.j2me.blueprints.smartticket.server.ejb.synchronizing;

import javax.ejb.*;
import javax.naming.*;
import java.rmi.*;
import java.util.*;
import com.sun.j2me.blueprints.smartticket.server.ejb.account.AccountLocal;
import com.sun.j2me.blueprints.smartticket.server.ejb.rating.MovieRatingData;
import com.sun.j2me.blueprints.smartticket.server.ejb.rating.MovieRatingLocalHome;
import com.sun.j2me.blueprints.smartticket.server.ejb.rating.MovieRatingLocal;
import com.sun.j2me.blueprints.smartticket.server.ejb.movie.MovieLocal;
import com.sun.j2me.blueprints.smartticket.server.ejb.movie.MovieLocalHome;

/**
 * @ejbLocal <{com.sun.j2me.blueprints.smartticket.server.ejb.synchronizing.SynchronizingLocal}>
 * @ejbDontSynchronizeNames
 * @ejbStateful
 * @ejbJNDIname ejb/smartticket/smartticket/Synchronizing
 * @ejbLocalJNDIname ejb/smartticket/smartticket/Synchronizing
 * @displayName SynchronizingSB
 * @undefined
 * @ejbTransactionAttribute Required
 * @ejbLocalHome <{SynchronizingLocalHome}>
 */
public class SynchronizingBean implements SessionBean {

    /**
     * @EJB-REF
     * @ReferenceType Entity
     * @ReferenceRemoteType EJB-LOCAL-REF
     * @RemoteInterface com.sun.j2me.blueprints.smartticket.server.ejb.movie.MovieLocal
     * @EJBLink MovieBean
     * @REF_JNDI_NAME ejb/smartticket/smartticket/Movie
     * @HomeInterface com.sun.j2me.blueprints.smartticket.server.ejb.movie.MovieLocalHome
     * @undefined
     */
    private static final String EJB_REF_MOVIE = "ejb/Movie";

    /**
     * @EJB-REF
     * @ReferenceType Entity
     * @ReferenceRemoteType EJB-LOCAL-REF
     * @RemoteInterface com.sun.j2me.blueprints.smartticket.server.ejb.rating.MovieRatingLocal
     * @EJBLink MovieRatingBean
     * @REF_JNDI_NAME ejb/smartticket/smartticket/MovieRating
     * @HomeInterface com.sun.j2me.blueprints.smartticket.server.ejb.rating.MovieRatingLocalHome
     * @undefined
     */
    private static final String EJB_REF_MOVIE_RATING = "ejb/MovieRating";

    /**
     * @EJB-REF
     * @ReferenceType Entity
     * @ReferenceRemoteType EJB-LOCAL-REF
     * @RemoteInterface com.sun.j2me.blueprints.smartticket.server.ejb.account.AccountLocal
     * @EJBLink AccountBean
     * @HomeInterface com.sun.j2me.blueprints.smartticket.server.ejb.account.AccountLocalHome
     * @REF_JNDI_NAME ejb/smartticket/smartticket/Account
     * @undefined
     */
    private static final String EJB_REF_ACCOUNT = "ejb/Account";

    /**
     * @EJB-REF
     * @ReferenceType Entity
     * @ReferenceRemoteType EJB-LOCAL-REF
     * @RemoteInterface com.sun.j2me.blueprints.smartticket.server.ejb.synchronizing.SyncClientLocal
     * @EJBLink AccountBean
     * @HomeInterface com.sun.j2me.blueprints.smartticket.server.ejb.synchronizing.SyncClientLocalHome
     * @REF_JNDI_NAME ejb/smartticket/smartticket/SyncClient
     * @undefined
     */
    private static final String EJB_REF_SYNC_CLIENT = "ejb/SyncClient";
    private SessionContext ctx;
    private Context context;
    private AccountLocal account;
    private MovieRatingLocalHome movieRatingHome;
    private MovieLocalHome movieHome;
    private SyncClientLocalHome syncClientHome;
    private SyncConduitLocal syncConduit;
    private SyncClientLocal syncClient = null;
    private HashMap updatedMovieRatings = new HashMap();
    private long initiationTime;
    private long timeShift;

    /**
     * @link dependency
     */
    /* # AccountBean lnkAccountBean; */

    /**
     * @link dependency
     */
    /* # SyncConduitBean lnkSyncConduitBean; */
    public void setSessionContext(SessionContext context) 
            throws RemoteException, EJBException {
        ctx = context;
    } 

    public void ejbActivate() throws EJBException {}

    public void ejbPassivate() throws EJBException {}

    public void ejbRemove() throws EJBException {}

    public void ejbCreate(AccountLocal account) 
            throws CreateException, EJBException {
        this.account = account;

        try {
            context = (Context) new InitialContext().lookup("java:comp/env");
            movieRatingHome = 
                (MovieRatingLocalHome) context.lookup(EJB_REF_MOVIE_RATING);
            movieHome = (MovieLocalHome) context.lookup(EJB_REF_MOVIE);
            syncClientHome = 
                (SyncClientLocalHome) context.lookup(EJB_REF_SYNC_CLIENT);
        } catch (Exception e) {
            throw new CreateException("SynchronizingBean.ejbCreate(): " 
                                      + e.getMessage());
        } 
    } 

    public SyncClientAnchor initiateSynchronization(SyncClientAnchor syncClientAnchor, 
            long clientTime) {
        syncConduit = account.getMovieRatingSyncConduit();

        if (syncClientAnchor.getClientId() == -1) {
            try {
                syncClient = 
                    syncClientHome.create(syncConduit.makeSyncClientId());

                syncConduit.getSyncClients().add(syncClient);
                syncClient.setLastSynchronizationTime(0L);
            } catch (CreateException ce) {
                throw new EJBException("SynchronizingBean.initiateSynchronization: " 
                                       + ce.getMessage());
            } 
        } else if (syncClient == null) {
            syncClient = 
                syncConduit.getSyncClient(syncClientAnchor.getClientId());

            if (syncClient == null) {
                try {
                    syncClient = 
                        syncClientHome.create(syncConduit.makeSyncClientId());

                    syncConduit.getSyncClients().add(syncClient);

                    return new SyncClientAnchor(syncClient.getId(), 0L, true);
                } catch (CreateException ce) {
                    throw new EJBException("SynchronizingBean.initiateSynchronization: " 
                                           + ce.getMessage());
                } 
            } 
        } else if (syncClient.getId() != syncClientAnchor.getClientId()) {
            syncClient = 
                syncConduit.getSyncClient(syncClientAnchor.getClientId());

            if (syncClient == null) {
                try {
                    syncClient = 
                        syncClientHome.create(syncConduit.makeSyncClientId());

                    syncConduit.getSyncClients().add(syncClient);

                    return new SyncClientAnchor(syncClient.getId(), 0L, true);
                } catch (CreateException ce) {
                    throw new EJBException("SynchronizingBean.initiateSynchronization: " 
                                           + ce.getMessage());
                } 
            } 
        } 

        if (syncClientAnchor.getClientId() == -1 
                || syncClientAnchor.getLastSyncTime() 
                   == syncClient.getLastSynchronizationTime()) {
            initiationTime = new Date().getTime();
            timeShift = 
                initiationTime 
                - clientTime;    // approximate due to network latency and so on..

            return new SyncClientAnchor(syncClient.getId(), initiationTime, 
                                        false);
        }