端到端J2ME应用开发实例——介绍Smart Ticket

public interface RequestHandler {
    RequestHandler getNextHandler();
    void init() throws ApplicationException;
    void destroy() throws ApplicationException;
}
abstract public class RemoteModelRequestHandler 
  implements RequestHandler, RemoteModel {
  private RemoteModelRequestHandler nextHandler;
  private Preferences preferences;
  protected static ProgressObserver progressObserver;
  public RemoteModelRequestHandler(
      RemoteModelRequestHandler nextHandler) {
    this.nextHandler = nextHandler;
  }
  public RequestHandler getNextHandler() {
    return nextHandler;
  }
  public void init() throws ApplicationException {
    if (nextHandler != null) {
      nextHandler.init();
    }
    return;
  }
  public void destroy() throws ApplicationException {
    if (nextHandler != null) {
      nextHandler.destroy();
    }
    return;
  }
  public void login(String userName, String password) 
      throws ModelException, ApplicationException {
    getRemoteModelRequestHandler().login(userName, password);
    return;
  } 
  public void createAccount(AccountInfo accountInfo) 
                            throws ModelException, 
                            ApplicationException {
    getRemoteModelRequestHandler().createAccount(accountInfo);
    return;
  }
  // Other action methods declared in RemoteModel
  // ...
}
            

public class RemoteModelProxy extends ModelObjectLoader 
                              implements RemoteModel {
  private RemoteModelRequestHandler requestHandlerChain;
  private Preferences preferences = null;
  private Hashtable movies = new Hashtable();
  public RemoteModelProxy(String serviceURL) 
                          throws ApplicationException {
    requestHandlerChain =
      new RMSCacheHandler(
        new HTTPCommunicationHandler(null, serviceURL));
    return;
  }
  // ...
  public Movie getMovie(String movieKey) 
                        throws ModelException, 
                        ApplicationException {
    Movie movie = (Movie) movies.get(movieKey);
    if (movie == null) {
      movie = requestHandlerChain.getMovie(movieKey);
      movies.put(movieKey, movie);
    } 
    return movie;
  } 
  // Other methods ...
}