沒有@Provides注釋的方法無法提供

Question

還有許多其他類似的問題，但是沒有一個答案適用於我的代碼。 我無法弄清楚我做錯了什么。

首先，我有一個NetworkModule用作ApplicationComponent的模塊：

@Module
open class NetworkModule {

    companion object {
        private val BASE = "http://www.example.com/"
    }

    @Provides @ApplicationScope
    fun provideClient(): OkHttpClient = OkHttpClient()

    @Provides @ApplicationScope
    fun provideMoshi(): Moshi {
        return Moshi.Builder().add(InstantAdapter).add(UriAdapter).build()
    }

    @Provides @ApplicationScope
    fun provideRetrofit(client: OkHttpClient, moshi: Moshi): Retrofit {
        return Retrofit.Builder().client(client).baseUrl(BASE)
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .addConverterFactory(MoshiConverterFactory.create(moshi))
                .build()
    }

    @Provides @ApplicationScope
    fun provideArticleService(retrofit: Retrofit): ArticleService {
        return retrofit.create(ArticleService::class.java)
    }

}

---

@ApplicationScope @Component(modules = arrayOf(ContextModule::class, RealmModule::class, NetworkModule::class))
interface ApplicationComponent {}

然后ApplicationComponent是建立在我的Application類：

class MyApplication : Application() {

    override fun onCreate() {
        super.onCreate()
        AndroidThreeTen.init(this)

        plantLog()
        drawDagger()
    }

    private fun drawDagger() {
        Injector.initializeApplicationComponent(this)
    }

    // ...

}

---

object Injector {

    lateinit var applicationComponent: ApplicationComponent
        private set

    fun initializeApplicationComponent(context: Context) {
        applicationComponent = DaggerApplicationComponent.builder()
                .contextModule(ContextModule(context))
                .networkModule(NetworkModule())
                .realmModule(RealmModule())
                .build()
    }

    // ...

}

然后我有一個ActivityModule是在所使用的ActivityComponent （其具有ApplicationComponent作為依賴）：

@Module
open class ActivityModule(private val activity: AppCompatActivity) {

    @Provides @ActivityScope @ActivityContext
    fun provideContext(): Context = activity

    @Provides @ActivityScope
    fun provideFragmentManager(): FragmentManager = activity.supportFragmentManager

}

---

@ActivityScope @Component(dependencies = arrayOf(ApplicationComponent::class), modules = arrayOf(ActivityModule::class))
interface ActivityComponent {

    fun inject(activity: MainActivity)

}

最后，我在MainActivity創建一個新的ActivityComponent ，並@Inject the ArticleService ：

class MainActivity : AppCompatActivity() {

    @Inject lateinit var service: ArticleService

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        DaggerActivityComponent.builder()
                .applicationComponent(Injector.applicationComponent)
                .activityModule(ActivityModule(this))
                .build().inject(this)

        service.getNewsArticles()
                .observeOn(AndroidSchedulers.mainThread())
                .subscribeOn(Schedulers.newThread())
                .subscribe(
                        { response -> onNext(response) },
                        { error -> onError(error) })
    }

    // ...

}

但是，當我嘗試構建時，即使我相信NetworkModule的provideArticleService()函數已正確標注，也會出現以下錯誤：

沒有@Provides或@Produces批注的方法就無法提供ArticleService。

Answer 1

您缺少了繼承到Activity范圍內的組件的置備方法。 使用子組件代替組件依賴關系，或者在應用程序組件中定義供應方法。

 @ApplicationScope @Component(modules = arrayOf(ContextModule::class, RealmModule::class, NetworkModule::class))
 interface ApplicationComponent {
      ArticleService articleService();
 }