GWT /杜松子酒Presenter實例化

Question

我已經按照this tutorial的建議實施了GWT應用程序。我還下載了示例代碼，並且我注意到演示的每個演示者都需要注入主演示器構造函數中以進行實例化。筆者在源包含在此：

public class GreetingPresenter extends WidgetPresenter<GreetingPresenter.Display> { 

    // FUDGE FACTOR! Although this is not used, having GIN pass the object 
    // to this class will force its instantiation and therefore will make the 
    // response presenter listen for events (via bind()). This is not a very good way to 
    // achieve this, but I wanted to put something together quickly - sorry! 
    private final GreetingResponsePresenter greetingResponsePresenter; 

    @Inject 
    public GreetingPresenter(final Display display, final EventBus eventBus, final DispatchAsync dispatcher, final GreetingResponsePresenter greetingResponsePresenter) { 
      super(display, eventBus);  
      this.dispatcher = dispatcher;  
      this.greetingResponsePresenter = greetingResponsePresenter;  
      bind(); 
} 

我覈實，如有主持人沒有得到GreetingPresenter注射，也不會被實例化。出於演示的目的，這很酷，因爲整個應用程序只有兩個演示者，但在真實世界的應用程序中，這可能是一個嚴重的不便。

完成Presenter實例化的正確方法是什麼？

編輯：包括參考GIN相關類：

演示模塊：

public class GreetingClientModule extends AbstractPresenterModule { 

    @Override 
    protected void configure() {   
     bind(EventBus.class).to(DefaultEventBus.class).in(Singleton.class); 
     bind(PlaceManager.class).in(Singleton.class);  
     bindPresenter(GreetingPresenter.class, GreetingPresenter.Display.class, GreetingView.class); 
     bindPresenter(GreetingResponsePresenter.class, GreetingResponsePresenter.Display.class, GreetingResponseView.class);   
     bind(AppPresenter.class).in(Singleton.class); 
     bind(CachingDispatchAsync.class); 
    } 
} 

Ginjector：

@GinModules({ ClientDispatchModule.class, GreetingClientModule.class }) 
public interface GreetingGinjector extends Ginjector { 

    AppPresenter getAppPresenter(); 
    PlaceManager getPlaceManager(); 

} 

Answer 1

我認爲你缺少你Ginjector和AbstractGinModule defini您可以從那個樣本中定義GIN綁定。
我建議從下面的教程中下載code，並查看GIN入門wiki。

GreetingGinjector：

@GinModules({ ClientDispatchModule.class, GreetingClientModule.class }) 
public interface GreetingGinjector extends Ginjector { 

    AppPresenter getAppPresenter(); 

    PlaceManager getPlaceManager(); 

} 

GreetingClientModule：

public class GreetingClientModule extends AbstractPresenterModule { 

    @Override 
    protected void configure() {   
     bind(EventBus.class).to(DefaultEventBus.class).in(Singleton.class); 
     bind(PlaceManager.class).in(Singleton.class); 

     bindPresenter(GreetingPresenter.class, GreetingPresenter.Display.class, GreetingView.class); 
     bindPresenter(GreetingResponsePresenter.class, GreetingResponsePresenter.Display.class, GreetingResponseView.class); 

     bind(AppPresenter.class).in(Singleton.class); 
     bind(CachingDispatchAsync.class); 
    } 
} 

入口點：

public class GreetMvp implements EntryPoint { 
    private final GreetingGinjector injector = GWT.create(GreetingGinjector.class); 

    public void onModuleLoad() { 
     final AppPresenter appPresenter = injector.getAppPresenter(); 
     appPresenter.go(RootPanel.get()); 

     injector.getPlaceManager().fireCurrentPlace(); 
    } 
} 

Answer 2

你可以通過使用Providers來解決這個問題。在我的杜松子酒模塊我宣佈我的演示/活動與它一起的觀點是這樣

// Content Area 
    bind(ContentActivityMapper.class).in(Singleton.class); 

    // Intro Page 
    bind(IntroPageActivity.class); 
    bind(IntroPageView.class).to(IntroPageViewImpl.class).in(Singleton.class); 

然後在活動映射器I使用這樣

public class ContentActivityMapper implements ActivityMapper { 

    @Inject Provider<IntroPageActivity> introPageProvider; 

    public Activity getActivity(Place place) { 

     if (place instanceof DefaultPlace) { 
     return introPageProvider.get().withPlace(new IntroPagePlace()); 
     }... 

我已在withPlace方法建立在供應商ActivityPresenter允許它在沒有參數的情況下被注入。該代碼看起來像這樣。

public class IntroPageActivity extends AbstractActivity { 

    private IntroPageView view; 

    @Inject 
    public IntroPageActivity(IntroPageView view) { 
     super(); 
     this.view = view; 
    } 

    public IntroPageActivity withPlace(IntroPagePlace place) { 
     return this; 
    } 

    @Override 
    public void start(AcceptsOneWidget containerWidget, EventBus eventBus) { 
     containerWidget.setWidget(view.asWidget()); 
    }...