使用 HILT 注入摘要 class（基础 activity）

Question

我刚刚开始尝试在我非常简单的项目中使用 Hilt。现在一切都在 Dagger2 上，但我想迁移到 Hilt。

我有一个 activity :

@AndroidEntryPoint
class MainActivity : BaseActivity() { 
    // SOME STUFF
}

还有像这样的 BaseActivity :

abstract class BaseActivity : AppCompatActivity() {
    // SOME STUFF
}

此外，我有一个 class 使用 baseActivity 来显示对话框。例如：

@FragmentScoped
class TestComponentImpl @Inject constructor(
    private val baseActivity: BaseActivity
) : TestComponent {

    override fun displayDialog() {
        MaterialDialog(baseActivity).show { ... 
    }
}

但是，当我尝试编译时，出现了这个错误：

BaseActivity cannot be provided without an @Provides-annotated method.

所以，我的问题是：如何构造函数注入抽象 class。我尝试了很多东西但没有成功，比如在 Hilt 模块中：

    @Provides
    @Singleton
    fun provideBaseActivity(): BaseActivity{
        return BaseActivity() // Of course, it can't work cause it's an abstract class
    }

或者（就像我对 Dagger 所做的那样）：

    @Provides
    @PerActivity
    fun appCompatActivity(baseActivity: BaseActivity) = baseActivity as AppCompatActivity

此外，我只是 Hilt 的初学者，所以，也许我错过了什么。我会继续搜索:)

感谢您的宝贵时间和回答:)

编辑：

我自己搜索了几天，这似乎有效，但似乎不太好...

@Singleton
@Provides
fun provideBaseActivity(baseActivity: BaseActivity): AppCompatActivity {
    return baseActivity
}

但前提是我像这样放置我的 baseActivity :

open class BaseActivity Inject constructor() : AppCompatActivity()

但是，在那之后，如果我尝试像这样在我的 TestComponentImpl 中使用注入的 baseActivity（就像我在 Hilt 之前使用 Dagger 所做的那样）：

override fun displayError() {
    Snackbar.make(
        baseActivity.findViewById(android.R.id.content),
        "My error text",
        Snackbar.LENGTH_LONG
    ).apply {
        show()
    }

我遇到另一个错误：

java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference

所以我不认为我的 baseActivity 注入做得很好。我会继续调查 ;)

Answer 1

有点hacky（type-casting）但应该可以用（未经测试，记下我的头顶所以随时让我知道如果某些东西没有按预期工作):

创建这样的 Module:

@Module
@InstallIn(ActivityComponent::class)
object BaseActivityModule {

  @Provides
  fun provideBaseActivity(activity: Activity): BaseActivity {
    check(activity is BaseActivity) { "Every Activity is expected to extend BaseActivity" }
    return activity as BaseActivity  
  }
}

最后一个演员as BaseActivity可能是不必要的。 Kotlin 编译器应该处理这个问题。

Answer 2

@Boysteuf @Bartek Lipinski

遇到以下错误：

error: [Dagger/MissingBinding] android.app.Activity cannot be provided without an @Inject constructor or an @Provides-annotated method.
  public abstract static class SingletonC implements EzeApp_GeneratedInjector,
                         ^
      android.app.Activity is injected at
          com.ezetap.consumerpaymentsdk.di.module.BaseActivityModule.provideBaseActivity(activity)
      com.ezetap.consumerpaymentsdk.base.BaseSDKActivity is injected at
          com.ezetap.consumerpaymentsdk.di.module.AppModule.provideServicePresenterPresenter(baseSDKActivity, …)
      com.ezetap.consumerpaymentsdk.presenters.ServicePresenter is injected at
          com.ezetap.consumerpaymentsdk.activity.ServiceSDKActivity.presenter
      com.ezetap.consumerpaymentsdk.activity.ServiceSDKActivity is injected at
          com.ezetap.consumerpaymentsdk.activity.ServiceSDKActivity_GeneratedInjector.injectServiceSDKActivity(com.ezetap.consumerpaymentsdk.activity.ServiceSDKActivity) [com.ezetap.consumerpaymentsdk.base.EzeApp_HiltComponents.SingletonC → com.ezetap.consumerpaymentsdk.base.EzeApp_HiltComponents.ActivityRetainedC → com.ezetap.consumerpaymentsdk.base.EzeApp_HiltComponents.ActivityC]
  The following other entry points also depend on it:
      com.ezetap.consumerpaymentsdk.activity.SimActivity_GeneratedInjector.injectSimActivity(com.ezetap.consumerpaymentsdk.activity.SimActivity) [com.ezetap.consumerpaymentsdk.base.EzeApp_HiltComponents.SingletonC → com.ezetap.consumerpaymentsdk.base.EzeApp_HiltComponents.ActivityRetainedC → com.ezetap.consumerpaymentsdk.base.EzeApp_HiltComponents.ActivityC]

AppModule

@Module(includes = [NetworkModule::class , BaseActivityModule::class ])
@InstallIn(SingletonComponent::class)
object AppModule {

    @Provides
    @Singleton
    fun provideBasePresenter(baseSDKActivity: BaseSDKActivity ,ezeApi: EzeApi, @ApplicationContext context: Context ) : BaseSDKPresenter  {
        return BaseSDKPresenter(baseSDKActivity, ezeApi , context )
    }


    @Provides
    @Singleton
    fun provideSimPresenter(baseSDKActivity: BaseSDKActivity, ezeApi: EzeApi , @ApplicationContext context: Context ) : SimPresenter  {
        return SimPresenter(baseSDKActivity , ezeApi , context)
    }

    @Provides
    @Singleton
    fun provideServicePresenterPresenter(baseSDKActivity: BaseSDKActivity,ezeApi: EzeApi , @ApplicationContext context: Context ) : ServicePresenter {
        return ServicePresenter(baseSDKActivity , ezeApi , context)
    }

}

BaseActivityModule

@Module
@InstallIn(ActivityComponent::class)
object BaseActivityModule {

     @Provides
     fun provideBaseActivity(activity :Activity): BaseSDKActivity {
        check(activity is BaseSDKActivity) { "Every Activity is expected to extend BaseActivity" }
        return activity as BaseSDKActivity
    }

}

BaseSDKActivity

open class BaseSDKActivity @Inject constructor() : AppCompatActivity() {
}

BaseSDKPresenter

@ActivityScoped
open class BaseSDKPresenter @Inject constructor(private val baseSDKActivity: BaseSDKActivity , private val ezeApi: EzeApi ,
                                                private val context: Context )

使用 HILT 注入摘要 class（基础 activity）

Inject abstract class (base activity) with HILT

android

kotlin

dependency-injection

dagger-hilt

AppModule

BaseActivityModule

BaseSDKActivity

BaseSDKPresenter