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

        syncClient.setLastSynchronizationTime(0L);    // to force slow sync

        return new SyncClientAnchor(syncClient.getId(), 0L, true);
    } 

    public MovieRatingData[] synchronizeMovieRatings(MovieRatingData[] movieRatings, 
            int conflictResolutionStrategyId) {
        try {
            syncConduit = account.getMovieRatingSyncConduit();

            Collection serverSideChanges = 
                syncConduit.getChangedSyncMetaData(syncClient.getLastSynchronizationTime());
            Map clientSideChanges = movieRatingsArrayToMap(movieRatings);

            updatedMovieRatings.clear();

            if (conflictResolutionStrategyId 
                    == SyncConstants.STRATEGY_FIRST_MODIFIED_WINS 
                    || conflictResolutionStrategyId 
                       == SyncConstants.STRATEGY_LAST_MODIFIED_WINS) {
                // Handle conflicting changes and build the list of updates
                for (Iterator i = serverSideChanges.iterator(); 
                        i.hasNext(); ) {
                    SyncMetaDataLocal serverSideChange = 
                        (SyncMetaDataLocal) i.next();
                    MovieRatingData clientSideChange = 
                        (MovieRatingData) clientSideChanges.get(serverSideChange.getId());

                    if (clientSideChange != null) {
                        // Align the time
                        clientSideChange.alignTime(timeShift);

                        // Conflicting changes
                        if ((conflictResolutionStrategyId == SyncConstants.STRATEGY_FIRST_MODIFIED_WINS && serverSideChange.getLastModificationTime() > clientSideChange.getLastModificationDate()) 
                                || (conflictResolutionStrategyId 
                                    == SyncConstants.STRATEGY_LAST_MODIFIED_WINS 
                                       && serverSideChange.getLastModificationTime() 
                                          < clientSideChange.getLastModificationDate())) {
                            if (clientSideChange.getModificationStatus() 
                                    == SyncConstants.STATUS_DELETED) {
                                removeMovieRating(clientSideChange.getMovieId());
                            } else {
                                updateMovieRating(clientSideChange);
                            } 
                        } else {
                            if (serverSideChange.getDeleted()) {
                                if (clientSideChange.getModificationStatus() 
                                        != SyncConstants.STATUS_DELETED) {
                                    clientSideChange.setModificationStatus(SyncConstants.STATUS_DELETED);
                                    updatedMovieRatings.put(clientSideChange.getMovieId(), 
                                                            clientSideChange);
                                } 
                            } else {
                                updatedMovieRatings.put(serverSideChange.getId(), 
                                                        account.getMovieRating(serverSideChange.getId()).getData());
                            } 
                        } 

                        clientSideChanges.remove(clientSideChange.getMovieId());
                    } else {
                        // Non-conflicting changes
                        MovieRatingData movieRating = 
                            !serverSideChange.getDeleted() 
                            ? account.getMovieRating(serverSideChange.getId()).getData() 
                            : new MovieRatingData(serverSideChange.getId(), 
                                                  serverSideChange.getLastModificationTime());

                        updatedMovieRatings.put(serverSideChange.getId(), 
                                                movieRating);
                    } 
                } 

                // Apply directly remaining non-conflicting client-side changes
                for (Iterator i = clientSideChanges.values().iterator(); 
                        i.hasNext(); ) {
                    MovieRatingData clientSideChange = 
                        (MovieRatingData) i.next();

                    updateMovieRating(clientSideChange);
                } 

                syncClient.setLastSynchronizationTime(initiationTime);

                return (MovieRatingData[]) new ArrayList(updatedMovieRatings.values()).toArray(new MovieRatingData[0]);
            } else {    // SyncConstants.STRATEGY_ASK_USER
                HashMap conflictingMovieRatings = new HashMap();

                // Handle conflicting changes and build the list of updates
                for (Iterator i = serverSideChanges.iterator(); 
                        i.hasNext(); ) {
                    SyncMetaDataLocal serverSideChange = 
                        (SyncMetaDataLocal) i.next();
                    MovieRatingData clientSideChange = 
                        (MovieRatingData) clientSideChanges.get(serverSideChange.getId());

                    if (clientSideChange != null) {
                        MovieRatingData movieRating = 
                            !serverSideChange.getDeleted() 
                            ? account.getMovieRating(serverSideChange.getId()).getData() 
                            : new MovieRatingData(serverSideChange.getId(), 
                                                  serverSideChange.getLastModificationTime());

                        conflictingMovieRatings.put(serverSideChange.getId(), 
                                                    movieRating);
                        clientSideChanges.remove(clientSideChange.getMovieId());
                    } else {
                        // Non-conflicting changes
                        MovieRatingData movieRating = 
                            !serverSideChange.getDeleted() 
                            ? account.getMovieRating(serverSideChange.getId()).getData() 
                            : new MovieRatingData(serverSideChange.getId(), 
                                                  serverSideChange.getLastModificationTime());

                        updatedMovieRatings.put(serverSideChange.getId(), 
                                                movieRating);
                    } 
                } 

                // Apply directly remaining non-conflicting client-side changes
                for (Iterator i = clientSideChanges.values().iterator(); 
                        i.hasNext(); ) {
                    MovieRatingData clientSideChange = 
                        (MovieRatingData) i.next();

                    if (clientSideChange.getModificationStatus() 
                            == SyncConstants.STATUS_DELETED) {
                        removeMovieRating(clientSideChange.getMovieId());
                    } else {
                        updateMovieRating(clientSideChange);
                    } 
                } 

                return (MovieRatingData[]) new ArrayList(conflictingMovieRatings.values()).toArray(new MovieRatingData[0]);
            } 
        } catch (Exception e) {
            e.printStackTrace(System.err);

            throw new EJBException("SynchronizingBean.synchronizeMovieRatings: " 
                                   + e);
        } 
    } 

    public MovieRatingData[] commitMovieRatings(MovieRatingData[] movieRatings) {
        try {
            syncConduit = account.getMovieRatingSyncConduit();

            for (int i = 0; i < movieRatings.length; i++) {
                MovieRatingData change = movieRatings[i];

                if (change.isModifiedOnClient()) {
                    if (change.getModificationStatus() 
                            == SyncConstants.STATUS_DELETED) {
                        removeMovieRating(change.getMovieId());
                    } else {
                        updateMovieRating(change);
                    } 
                } else {
                    if (change.getModificationStatus() 
                            == SyncConstants.STATUS_DELETED) {
                        updatedMovieRatings.put(change.getMovieId(), change);
                    } else {
                        MovieRatingLocal movieRating = 
                            account.getMovieRating(change.getMovieId());

                        if (movieRating != null) {
                            updatedMovieRatings.put(change.getMovieId(), 
                                                    movieRating.getData());
                        } 
                    } 
                } 
            } 

            syncClient.setLastSynchronizationTime(initiationTime);

            return (MovieRatingData[]) new ArrayList(updatedMovieRatings.values()).toArray(new MovieRatingData[0]);
        } catch (Exception e) {
            throw new EJBException("SynchronizingBean.synchronizeMovieRatings: " 
                                   + e);
        } 
    } 

    private Map movieRatingsArrayToMap(MovieRatingData[] movieRatings) {
        Map map = new HashMap();

        for (int i = 0; i < movieRatings.length; i++) {
            map.put(movieRatings[i].getMovieId(), movieRatings[i]);
        } 

        return map;
    } 

    private void updateMovieRating(MovieRatingData data) 
            throws FinderException, CreateException, RemoveException {
        MovieRatingLocal movieRating = 
            account.getMovieRating(data.getMovieId());

        if (movieRating == null) {
            SyncMetaDataLocal metaData = 
                syncConduit.getSyncMetaData(data.getMovieId());

            if (metaData != null) {
                metaData.remove();
            } 

            MovieLocal movie = movieHome.findByPrimaryKey(data.getMovieId());

            movieRating = movieRatingHome.create(movie, account);
        } 

        movieRating.setData(data, initiationTime);

        return;
    } 

    private void removeMovieRating(String movieId) 
            throws FinderException, CreateException, RemoveException {
        MovieRatingLocal movieRating = account.getMovieRating(movieId);

        if (movieRating != null) {
            movieRating.remove();
        } 

        return;
    } 

}