Dagger2：如果没有 @Provides-annotated 方法，就无法提供 ViewModel

Posted 2023-04-19

【中文标题】Dagger2：如果没有 @Provides-annotated 方法，就无法提供 ViewModel

【英文标题】：Dagger2: ViewModel cannot be provided without an @Provides-annotated method

【发布时间】：2019-06-21 07:31:16

【问题描述】：

我正在遵循 Google 使用的 GithubBrowserSample 架构。但是在建设项目时遇到了麻烦。

我已将项目迁移到 androidX。我在 *** 上尝试了许多可用的答案，但没有成功。 这是我在构建时遇到的构建异常：

e:/windows/Apps/Verifi/VerifiApp/app/build/tmp/kapt3/stubs/debug/com/verifi/di/component/AppComponent.java:11: error: [Dagger/MissingBinding] [dagger.android.AndroidInjector.inject(T)] java.util.Map<java.lang.Class<? extends androidx.lifecycle.ViewModel>,javax.inject.Provider<androidx.lifecycle.ViewModel>> cannot be provided without an @Provides-annotated method.
public abstract interface AppComponent extends dagger.android.AndroidInjector<com.verifi.VerifiApp> 
                ^
      java.util.Map<java.lang.Class<? extends androidx.lifecycle.ViewModel>,javax.inject.Provider<androidx.lifecycle.ViewModel>> is injected at
          com.verifi.viewmodel.AppViewModelFactory.<init>(creators)
      com.verifi.viewmodel.AppViewModelFactory is injected at
          com.verifi.ui.auth.AuthActivity.appViewModelFactory
      com.verifi.ui.auth.AuthActivity is injected at
          dagger.android.AndroidInjector.inject(T)
  component path: com.verifi.di.component.AppComponent → com.verifi.di.module.ActivityBindingModule_AuthActivity.AuthActivitySubcomponent

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:kaptDebugKotlin'.

VerifiApp.kt

class VerifiApp: Application(), HasActivityInjector 

    @Inject
    lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Activity>

    override fun onCreate() 
        super.onCreate()

        if (BuildConfig.DEBUG) 
            Timber.plant(Timber.DebugTree())
        

        AppInjector.init(this)
    

    override fun activityInjector() = dispatchingAndroidInjector

AppComponent.kt：

@Singleton
@Component(
    modules = [AndroidSupportInjectionModule::class,
        AppModule::class,
        ActivityBindingModule::class])
interface AppComponent: AndroidInjector<VerifiApp> 
    @Component.Builder
    interface Builder 

        @BindsInstance
        fun application(application: Application): Builder

        fun build(): AppComponent
    

    override fun inject(verifiApp: VerifiApp)

AppModule.kt：

@Module(includes = [ViewModelBindingModule::class])
class AppModule 

    @Provides
    @Singleton
    internal fun provideContext(application: Application): Context = application

    @Provides
    @Singleton
    internal fun getRemoteSource(remoteDataManager: RemoteDataManager): IRemoteSource = remoteDataManager

    @Provides
    @Singleton
    internal fun provideDataManger(appDataManager: AppDataManager): IAppDataSource = appDataManager

    @Singleton
    @Provides
    fun provideVerifiService(): VerifiService 
        return Retrofit.Builder()
            .baseUrl("https://api.github.com/")
            .addConverterFactory(GsonConverterFactory.create())
            .addCallAdapterFactory(LiveDataCallAdapterFactory())
            .build()
            .create(VerifiService::class.java)
    

ViewModelBindingModule：：

@Suppress("unused")
@Module(includes = [AuthViewModelsBindingModule::class])
abstract class ViewModelBindingModule 

    @Binds
    abstract fun bindViewModelFactory(factory: AppViewModelFactory): ViewModelProvider.Factory

    @Binds
    @IntoMap
    @ViewModelKey(AuthViewModel::class)
    abstract fun bindAuthViewModel(authViewModel: AuthViewModel): AuthViewModel

任何帮助将不胜感激。

【参考方案1】：

abstract fun bindAuthViewModel(authViewModel: AuthViewModel): AuthViewModel

应该返回 ViewModel 而不是 AuthViewModel

【讨论】：

请查看***.com/questions/55669810/…

【参考方案2】：

当我将 java 代码更改为 kotlin 形式时，它对我有用

@Documented
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@MapKey
public @interface ViewModelKey 
    Class<? extends ViewModel> value();

到

@Target(AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER)
@MapKey
annotation class ViewModelKey(val value: KClass<out ViewModel>)

从

public class ViewModelProviderFactory implements ViewModelProvider.Factory 

    private static final String TAG = "ViewModelProviderFactor";

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

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

    @Override
    public <T extends ViewModel> T create(Class<T> modelClass) 
        Provider<? extends ViewModel> creator = creators.get(modelClass);
        if (creator == null)  // if the viewmodel has not been created

            // loop through the allowable keys (aka allowed classes with the @ViewModelKey)
            for (Map.Entry<Class<? extends ViewModel>, Provider<ViewModel>> entry : creators.entrySet()) 

                // if it's allowed, set the Provider<ViewModel>
                if (modelClass.isAssignableFrom(entry.getKey())) 
                    creator = entry.getValue();
                    break;
                
            
        

        // if this is not one of the allowed keys, throw exception
        if (creator == null) 
            throw new IllegalArgumentException("unknown model class " + modelClass);
        

        // return the Provider
        try 
            return (T) creator.get();
         catch (Exception e) 
            throw new RuntimeException(e);
        
    

到

class ViewModelProviderFactory @Inject constructor(private val viewModelsMap: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>) :
    ViewModelProvider.Factory 

    override fun <T : ViewModel> create(modelClass: Class<T>): T 
        val creator = viewModelsMap[modelClass] ?:
        viewModelsMap.asIterable().firstOrNull 
            modelClass.isAssignableFrom(it.key)
        ?.value ?: throw IllegalArgumentException("unknown model class $modelClass")
        return try 
            creator.get() as T
         catch (e: Exception) 
            throw RuntimeException(e)
        
    

【讨论】：

仅将 @JvmSuppressWildcards 添加到 Provider 为我做了这件事。感谢您发布此内容。

【参考方案3】：

它在 Kotlin Dagger 处理器中的问题 您应该将您的 ViewModelFactory 和 ViewModelKey 转换为 Java，因为它对我有用