Question

我正在使用带有匕首2的多重绑定来注入视图模型。我必须在视图模型中使用构造函数注入，因此需要使用ViewModelProvider.Factory注入视图模型。以下是我完成的配置

AppComponent.java

        @Singleton
        @Component(modules = {AndroidInjectionModule.class,
                ActivityBuilderModule.class,
                Bindings.class,
                NetworkModule.class,
                ViewModelModule.class})
        public interface AppComponent {
            void inject(App app);
        }

ViewModelModule.java

        @Module
        public interface ViewModelModule {
            @Binds
            @IntoMap
            @ViewModelKey(HomeScreenViewModel.class)
            ViewModel homeScreenViewModel(HomeScreenViewModel homeScreenViewModel);

        }

AppViewModelFactory.java

        @Singleton
        public class AppViewModelFactory implements ViewModelProvider.Factory {

            private final Map<Class<? extends ViewModel>, Provider<ViewModel>> creators;

            @Inject
            public AppViewModelFactory(Map<Class<? extends ViewModel>, Provider<ViewModel>> creators) {
                this.creators = creators;
            }

            @SuppressWarnings("unchecked")
            @Override
            public <T extends ViewModel> T create(Class<T> modelClass) {
                Provider<? extends ViewModel> creator = creators.get(modelClass);
                if (creator == null) {
                    for (Map.Entry<Class<? extends ViewModel>, Provider<ViewModel>> entry : creators.entrySet()) {
                        if (modelClass.isAssignableFrom(entry.getKey())) {
                            creator = entry.getValue();
                            break;
                        }
                    }
                }
                if (creator == null) {
                    throw new IllegalArgumentException("unknown model class " + modelClass);
                }
                try {
                    return (T) creator.get();
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            }
        }

HomeScreenViewModel.class

        public class HomeScreenViewModel extends BaseViewModel {

            @Inject
            public HomeScreenViewModel(Repository repository) { // repository an Application scoped (@Singleton) dependency
                mRepository = repository;
            }

        }

一切正常，当我想通过构造函数注入向该视图模型注入活动范围内的依赖项时，问题就开始了。

我有一些通过活动意图传递的参数，我想对其进行解析并将其作为依赖项传递给我的ViewModel。以下是使我的工作更加清晰的代码

ActivityBuilderModule.java

@Module
public abstract class ActivityBuilderModule {
    @ContributesAndroidInjector(modules = {HomeScreenModule.class})
    abstract HomeScreenActivity provideHomeScreenActivity();
}

HomeScreenModule.class

@Module
public class HomeScreenModule {

    @Provides
    public Bundle provideExtras(HomeScreenActivity homeActivity){
        return homeActivity.getIntent().getExtras(); // say I'm extracting extras from activity intent and I need to supply it to viewmodel
    }
}

我的ViewModel就像

  @Inject
    public HomeScreenViewModel(Repository repository, Bundle bundle) {
        mRepository = repository;
        mBundle = bundle;
    }

现在，它的抛出错误

error: [Dagger/MissingBinding] android.os.Bundle cannot be provided without an @Inject constructor or an @Provides-annotated method.

我知道出现错误是因为ViewModelProvider.Factory是在应用程序范围内创建的单例组件，将无法注入活动范围内的此bundle。有其他替代方法吗？现在，我在ViewModel上添加了setter，并在创建ViewModel之后手动设置了包。但我更喜欢在这里进行构造函数注入。有人知道该怎么做吗？

如何使用Dagger2

0 个答案: