如果没有@Provides 注释方法，则无法提供 Dagger 2 LocalDataSource

Question

我正在尝试通过使用 DI 创建存储库模式来遵循与 here 中相同的示例。问题是我收到以下错误：

"Error:(16, 20) error: @mvp.model.di.scope.Local mvp.model.repository.local.GameLocalDataSource cannot be provided without an @Provides-annotated method. @mvp.model.di.scope.Local mvp.model.repository.local.GameLocalDataSource is injected at mvp.model.repository.GameRepository.(gameLocalDataSource, …) mvp.model.repository.GameRepository is provided at mvp.model.di.component.RepositoryComponent.getGameRepository()"

这是与应用相关的代码：

public class GameApplication extends Application {
private RepositoryComponent repositoryComponent;

@Override
public void onCreate() {
    super.onCreate();
    if (LeakCanary.isInAnalyzerProcess(this)) {
        // This process is dedicated to LeakCanary for heap analysis.
        // You should not init your app in this process.
        return;
    }
    LeakCanary.install(this);
    // Normal app init code...
    repositoryComponent = DaggerRepositoryComponent.builder()
            .applicationModule(new ApplicationModule((getApplicationContext())))
            .build();
}

public RepositoryComponent getRepositoryComponent() {
    return repositoryComponent;
}
}

这是我的 RepositoryComponent:

@Singleton
@Component(modules = {RepositoryModule.class, ApplicationModule.class})
public interface RepositoryComponent {
    GameRepository getGameRepository();
}

这是RepositoryModule：

    @Module
public class RepositoryModule {
    @Singleton
    @Provides
    @Local
    GameDataSource provideLocalDataSource(Context context) {
        return new GameLocalDataSource(context);
    }

    @Singleton
    @Provides
    @Remote
    GameDataSource provideRemoteDataSource() {
        return new GameRemoteDataSource();
    }
}

最后，ApplicationModule:

    @Module
public final class ApplicationModule {
    private Context context;

    public ApplicationModule(Context context) {
        this.context = context;
    }

    @Provides
    Context providesContext() {
        return context;
    }
}

这是我的大部分 GameRepository class:

@Singleton
public class GameRepository implements GameDataSource {
    private GameDataSource remoteDataSource;
    private GameDataSource localDataSource;

    @Inject
    public GameRepository(@Local GameLocalDataSource gameLocalDataSource, @Remote GameRemoteDataSource gameRemoteDataSource) {
        remoteDataSource = gameRemoteDataSource;
        localDataSource = gameLocalDataSource;
    }

此外，如上述示例所示，我创建了几个范围，@Local 和 @Remote，因为我的两个数据源具有相同的类型，Dagger 需要区分它们。

@Qualifier
@Documented
@Retention(RetentionPolicy.RUNTIME)
public @interface Local {

}

我与 dagger 相关的其余代码，只是构造函数中我想注入依赖项的 @Inject。此外，DaggerRepositoryComponent 永远不会在 GameApplication class.

中生成

非常感谢您的提前帮助！

Answer 1

GameLocalDataSource cannot be provided without an @Provides-annotated method

您在代码中的某处尝试 @Inject GameLocalDataSource，但您已在模块中指定如何提供 GameDataSource， 而不是 GameLocalDataSource.

...
GameDataSource provideLocalDataSource(Context context) {
    return new GameLocalDataSource(context);
}
...

要么让Dagger注入GameDataSource，要么描述Dagger如何提供GameLocalDataSource。

...
GameLocalDataSource provideLocalDataSource(Context context) {
    return new GameLocalDataSource(context);
}
...

如果没有@Provides 注释方法，则无法提供 Dagger 2 LocalDataSource

Dagger 2 LocalDataSource cannot be provided without @Provides annotated method

java

android

dependency-injection

dagger

dagger-2