GWT / Gin Presenter实例化

Question

我按照本教程的建议实现了GWT应用程序。 我还下载了示例代码，我注意到演示的每个演示者都需要在主要的presenter构造函数中注入以进行实例化。 作者将此内容包括在内容中：

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();
}

我验证了如果任何Presenter没有在GreetingPresenter中注入，它将不会被实例化。 出于演示目的，这很酷，因为整个应用程序只有两个演示者，但在真实世界的应用程序中，这可能是一个非常不方便。

完成Presenter实例化的正确方法是什么？

编辑：包括GIN相关课程供参考：

演示者模块：

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

您可以使用Providers解决此问题。 在我的Gin模块中，我声明了我的Presenter / Activity以及它的视图

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

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

然后在Activity Mapper中我使用这样的提供者

public class ContentActivityMapper implements ActivityMapper {

    @Inject Provider<IntroPageActivity> introPageProvider;

    public Activity getActivity(Place place) {

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

我在ActivityPresenter上设置了withPlace方法，允许在没有参数的情况下注入它。 该代码看起来像这样。

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());
    }...

Answer 2

我认为您缺少Ginjector和AbstractGinModule定义，您可以在该定义中定义该样本的GIN绑定。
我建议从上面提到的教程中下载代码 ，并查看GIN入门维基 。

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);
    }
}

入口点 ：

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();
    }
}