如何使用dagger.android注入抽象的BaseActivity及其子类？

Question

如何使用dagger.android注入抽象的BaseActivity及其子类？

androiddependency-injectionkotlindagger-2

6

我正在使用Dagger 2中的新dagger.android包，在我的项目中注入Android依赖项。

I need all my Activities to be a subclass of an abstract BaseActivity

In my BaseActivity I have member variables to be injected. This way:

abstract class BaseActivity : AppCompatActivity() {
    @Inject
    lateinit var prefs: MyPreferenceDataStore
    ...// more @Injected members
}

I do it because I want subclasses of BaseActiviy can have access to injected members of BaseActivity:

class SubClassActivity : BaseActivity() {
    override fun onCreate(savedInstanceState: Bundle) {                
        val x = prefs.getXXX //use prefs variable from parent class
    }
}

This is my ApplicationComponent:

@Singleton @Component(modules = arrayOf(
                ApplicationModule::class,
                ActivityBindingModule::class,
                AndroidSupportInjectionModule::class
            ))
interface ApplicationComponent {
    @Component.Builder interface Builder {
        @BindsInstance
        fun application(application: Application): Builder
        fun build(): ApplicationComponent
    }
    fun inject(app: AndroidApplication)
}

The ApplicationModule class has simple @Provides annotated methods:

@Module
class ApplicationModule {
    @Singleton @Provides
    fun providesMyPreferenceDataStore(context: Context): MyPreferenceDataStore {
        return MyPreferenceDataStoreImpl(context)
    }
    // more @Provides annotated methods
}

I think the problem is in my ActivityBindingModule

@Module
abstract class ActivityBindingModule {

    @PerActivity
    @ContributesAndroidInjector(
        modules = arrayOf(BaseActivityModule::class
    ))
    abstract fun bindBaseActivity(): BaseActivity

    @PerActivity
    @ContributesAndroidInjector(
        modules = arrayOf(
            BaseActivityModule::class
    ))
    abstract fun bindSubClassActivity(): SubClassActivity
}

这是我到目前为止尝试过的：

Make the bindSubClassActivity() method not to depend of BaseActivityModule::class, didn't work.

Move the providesMyPreferenceDataStore from ApplicationModule to the BaseActivityModule, so that the class is:

@Module
class BaseActivityModule {
    @PerActivity @Provides
    fun providesMyPreferenceDataStore(context: Context): MyPreferenceDataStore {
        return MyPreferenceDataStoreImpl(context)
    }
}

这是我收到的错误：

Error: [dagger.android.AndroidInjector.inject(T)] com.example.BaseActivity cannot
be provided without an @Provides-annotated method.
This type supports members injection but cannot
be implicitly provided.

- Jorge E. Hernández

BaseActivityModule 代码在哪里？ - Ahmed Abdelmeged

嗨@AhmedAbd-Elmeged，请查看编辑。 - Jorge E. Hernández

1个回答

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- Ahmed Abdelmeged · Accepted Answer

我不完全理解你想做什么，但这个解决方案是基于我所理解的内容。

AppComponent 应该像这样：

@Singleton
@Component(modules = [
    AndroidSupportInjectionModule::class,
    AppModule::class,
    ActivityModule::class])
interface AppComponent : AndroidInjector<DaggerApplication> {

    @Component.Builder
    interface Builder {
        @BindsInstance
        fun application(application: Application): Builder

        fun build(): AppComponent
    }
}

您的基础活动，它将注入所有对象。

abstract class BaseActivity : DaggerAppCompatActivity() {

    @Inject
    lateinit var prefs: SharedPreferences

    //other objects to inject

}

它将被继承的活动，例如：MainActivity。

class MainActivity : BaseActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        prefs.getBoolean("s", true)
    }

}

活动模块

@Module
abstract class ActivityModule {

    @ContributesAndroidInjector
    abstract fun bindMainActivity(): MainActivity

    @ContributesAndroidInjector
    abstract fun bindBaseActivity():BaseActivity

}

应用程序模块

@Module
class AppModule {

    @Singleton
    @Provides
    fun providesMyPreferenceDataStore(application: Application): SharedPreferences {
        return application.getSharedPreferences("test", Context.MODE_PRIVATE)
    }

}