Google Web Toolkit (GWT) MVP Example (4)

最新推荐文章于 2025-06-06 16:53:31 发布

原创最新推荐文章于 2025-06-06 16:53:31 发布 · 169 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#GWT #Google #Web #Flash #.net

技术专栏收录该内容

13 篇文章

订阅专栏

本文介绍了一种使用Gin框架和Google Web Toolkit (GWT)构建客户端-服务器应用程序的方法。通过创建缓存调度器并整合Gin模块，实现了高效的数据交互。同时，服务器端也进行了配置以支持发送问候消息的业务逻辑。

At this point, the client code should start to compile but there is still more to do before we can run it. We need some utility classes for the dispatcher and Gin:

CachingDispatchAsync.java

 
   01.
   package co.uk.hivedevelopment.greet.client; 
  
   02.
   import java.util.HashMap; 
  
   03.
   import java.util.Map; 
  
   04.
   import com.google.gwt.user.client.rpc.AsyncCallback; 
  
   05.
   import com.google.inject.Inject; 
  
   06.
   import net.customware.gwt.dispatch.client.DispatchAsync; 
  
   07.
   import net.customware.gwt.dispatch.shared.Action; 
  
   08.
   import net.customware.gwt.dispatch.shared.Result; 
  
   09.
   /** 
  
   10.
   * Dispatcher which support caching of data in memory 
  
   11.
   * 
  
   12.
   */ 
  
   13.
   public class CachingDispatchAsync implements DispatchAsync { 
  
   14.
    private DispatchAsync dispatcher; 
  
   15.
    private Map, Result> cache = new HashMap, Result>(); 
  
   16.
    @Inject 
  
   17.
    public CachingDispatchAsync(final DispatchAsync dispatcher) { 
  
   18.
     this.dispatcher = dispatcher; 
  
   19.
    } 
  
   20.
    /* 
  
   21.
     * (non-Javadoc) 
  
   22.
     * @see net.customware.gwt.dispatch.client.DispatchAsync#execute(A, com.google.gwt.user.client.rpc.AsyncCallback) 
  
   23.
     */ 
  
   24.
    public , R extends Result> void execute(final A action, final AsyncCallback callback) { 
  
   25.
     dispatcher.execute(action, callback); 
  
   26.
    } 
  
   27.
    /** 
  
   28.
     * Execute the give Action. If the Action was executed before it will get fetched from the cache 
  
   29.
     * 
  
   30.
     * @param Action implementation 
  
   31.
     * @param Result implementation 
  
   32.
     * @param action the action 
  
   33.
     * @param callback the callback 
  
   34.
     */ 
  
   35.
    @SuppressWarnings("unchecked") 
  
   36.
    public , R extends Result> void executeWithCache(final A action, final AsyncCallback callback) { 
  
   37.
     final Result r = cache.get(action); 
  
   38.
       
   39.
     if (r != null) { 
  
   40.
      callback.onSuccess((R) r); 
  
   41.
     } 
  
   42.
     else { 
  
   43.
      dispatcher.execute(action, new AsyncCallback() { 
  
   44.
       public void onFailure(Throwable caught) { 
  
   45.
        callback.onFailure(caught); 
  
   46.
       } 
  
   47.
       public void onSuccess(R result) { 
  
   48.
        cache.put((Action) action, (Result) result); 
  
   49.
        callback.onSuccess(result); 
  
   50.
       } 
  
   51.
      }); 
  
   52.
     } 
  
   53.
    } 
  
   54.
    /** 
  
   55.
     * Clear the cache 
  
   56.
     */ 
  
   57.
    public void clear() { 
  
   58.
     cache.clear(); 
  
   59.
    } 
  
   60.
   }

GreetingClientModule.java

 
   01.
   package co.uk.hivedevelopment.greet.client.gin; 
  
   02.
   import net.customware.gwt.presenter.client.DefaultEventBus; 
  
   03.
   import net.customware.gwt.presenter.client.EventBus; 
  
   04.
   import net.customware.gwt.presenter.client.gin.AbstractPresenterModule; 
  
   05.
   import net.customware.gwt.presenter.client.place.PlaceManager; 
  
   06.
   import co.uk.hivedevelopment.greet.client.CachingDispatchAsync; 
  
   07.
   import co.uk.hivedevelopment.greet.client.mvp.AppPresenter; 
  
   08.
   import co.uk.hivedevelopment.greet.client.mvp.GreetingPresenter; 
  
   09.
   import co.uk.hivedevelopment.greet.client.mvp.GreetingResponsePresenter; 
  
   10.
   import co.uk.hivedevelopment.greet.client.mvp.GreetingResponseView; 
  
   11.
   import co.uk.hivedevelopment.greet.client.mvp.GreetingView; 
  
   12.
   import com.google.inject.Singleton; 
  
   13.
   public class GreetingClientModule extends AbstractPresenterModule { 
  
   14.
    @Override 
  
   15.
    protected void configure() {   
  
   16.
     bind(EventBus.class).to(DefaultEventBus.class).in(Singleton.class); 
  
   17.
     bind(PlaceManager.class).in(Singleton.class); 
  
   18.
       
   19.
     bindPresenter(GreetingPresenter.class, GreetingPresenter.Display.class, GreetingView.class); 
  
   20.
     bindPresenter(GreetingResponsePresenter.class, GreetingResponsePresenter.Display.class, GreetingResponseView.class); 
  
   21.
       
   22.
     bind(AppPresenter.class).in(Singleton.class); 
  
   23.
     bind(CachingDispatchAsync.class); 
  
   24.
    } 
  
   25.
   }

GreetingGinjector.java

 
   01.
   package co.uk.hivedevelopment.greet.client.gin; 
  
   02.
   import net.customware.gwt.dispatch.client.gin.ClientDispatchModule; 
  
   03.
   import net.customware.gwt.presenter.client.place.PlaceManager; 
  
   04.
   import co.uk.hivedevelopment.greet.client.mvp.AppPresenter; 
  
   05.
   import com.google.gwt.inject.client.GinModules; 
  
   06.
   import com.google.gwt.inject.client.Ginjector; 
  
   07.
   @GinModules({ ClientDispatchModule.class, GreetingClientModule.class }) 
  
   08.
   public interface GreetingGinjector extends Ginjector { 
  
   09.
    AppPresenter getAppPresenter(); 
  
   10.
    PlaceManager getPlaceManager(); 
  
   11.
   }

Now we tie all this together by replacing the existing module entry class with the following:

GreetMvp.java

 
   01.
   package co.uk.hivedevelopment.greet.client; 
  
   02.
   import co.uk.hivedevelopment.greet.client.gin.GreetingGinjector; 
  
   03.
   import co.uk.hivedevelopment.greet.client.mvp.AppPresenter; 
  
   04.
   import com.google.gwt.core.client.EntryPoint; 
  
   05.
   import com.google.gwt.core.client.GWT; 
  
   06.
   import com.google.gwt.user.client.ui.RootPanel; 
  
   07.
   public class GreetMvp implements EntryPoint { 
  
   08.
    private final GreetingGinjector injector = GWT.create(GreetingGinjector.class); 
  
   09.
    public void onModuleLoad() { 
  
   10.
     final AppPresenter appPresenter = injector.getAppPresenter(); 
  
   11.
     appPresenter.go(RootPanel.get()); 
  
   12.
     injector.getPlaceManager().fireCurrentPlace(); 
  
   13.
    } 
  
   14.
   }

Server Components

Okay, now let's define the server side. We need to configure Guice and the dispatch handler plus we need to provide an implementation for the SendGreeting action.

SendGreetingHandler.java

 
   01.
   package co.uk.hivedevelopment.greet.server.handler; 
  
   02.
   import javax.servlet.ServletContext; 
  
   03.
   import javax.servlet.http.HttpServletRequest; 
  
   04.
   import net.customware.gwt.dispatch.server.ActionHandler; 
  
   05.
   import net.customware.gwt.dispatch.server.ExecutionContext; 
  
   06.
   import net.customware.gwt.dispatch.shared.ActionException; 
  
   07.
   import org.apache.commons.logging.Log; 
  
   08.
   import co.uk.hivedevelopment.greet.shared.rpc.SendGreeting; 
  
   09.
   import co.uk.hivedevelopment.greet.shared.rpc.SendGreetingResult; 
  
   10.
   import com.google.inject.Inject; 
  
   11.
   import com.google.inject.Provider; 
  
   12.
   public class SendGreetingHandler implements ActionHandler<SendGreeting, SendGreetingResult> { 
  
   13.
    private final Log logger; 
  
   14.
    private final Provider<ServletContext> servletContext; 
  
   15.
    private final Provider<HttpServletRequest> servletRequest; 
  
   16.
    @Inject 
  
   17.
    public SendGreetingHandler(final Log logger, 
  
   18.
          final Provider<ServletContext> servletContext,        
  
   19.
          final Provider<HttpServletRequest> servletRequest) { 
  
   20.
     this.logger = logger; 
  
   21.
     this.servletContext = servletContext; 
  
   22.
     this.servletRequest = servletRequest; 
  
   23.
    } 
  
   24.
    @Override 
  
   25.
    public SendGreetingResult execute(final SendGreeting action, 
  
   26.
          final ExecutionContext context) throws ActionException { 
  
   27.
     final String name = action.getName(); 
  
   28.
        
   29.
     try { 
  
   30.
      String serverInfo = servletContext.get().getServerInfo(); 
  
   31.
        
   32.
      String userAgent = servletRequest.get().getHeader("User-Agent"); 
  
   33.
        
   34.
      final String message = "Hello, " + name + "! 
  
   35.
   I am running " + serverInfo 
  
   36.
        + ". 
  
   37.
   It looks like you are using: 
  
   38.
   " + userAgent; 
  
   39.
        
   40.
      //final String message = "Hello " + action.getName();  
  
   41.
        
   42.
      return new SendGreetingResult(name, message); 
  
   43.
     } 
  
   44.
     catch (Exception cause) { 
  
   45.
      logger.error("Unable to send message", cause); 
  
   46.
        
   47.
      throw new ActionException(cause); 
  
   48.
     } 
  
   49.
    } 
  
   50.
    @Override 
  
   51.
    public void rollback(final SendGreeting action, 
  
   52.
           final SendGreetingResult result, 
  
   53.
           final ExecutionContext context) throws ActionException { 
  
   54.
     // Nothing to do here 
  
   55.
    } 
  
   56.
      
   57.
    @Override 
  
   58.
    public Class<SendGreeting> getActionType() { 
  
   59.
     return SendGreeting.class; 
  
   60.
    } 
  
   61.
   }

DispatchServletModule.java

 
   01.
   package co.uk.hivedevelopment.greet.server.guice; 
  
   02.
   import net.customware.gwt.dispatch.server.service.DispatchServiceServlet; 
  
   03.
   import com.google.inject.servlet.ServletModule; 
  
   04.
   public class DispatchServletModule extends ServletModule { 
  
   05.
    @Override 
  
   06.
    public void configureServlets() { 
  
   07.
     // NOTE: the servlet context will probably need changing 
  
   08.
     serve("/greetmvp/dispatch").with(DispatchServiceServlet.class); 
  
   09.
    } 
  
   10.
   }