android - 有什么方法可以从应用程序组件 dagger2 访问贡献模块实例

Question

我创建了一个小样本来测试 dagger2 的实现。我创建了一个实用程序类，其中将注入(inject)一个 Activity 的实例。有什么方法可以使用 dagger2 在 Activity 本身中获取这个实用程序类实例

CoreApplication.kt

class CoreApplication : Application(), HasActivityInjector {
    @Inject
    internal lateinit var dispatchingActivityInjector: DispatchingAndroidInjector<Activity>

    override fun activityInjector(): AndroidInjector<Activity> {
        return dispatchingActivityInjector    }

    val component: AppComponent by lazy {
        DaggerAppComponent
                .builder()
                .application(this)
                .sharedPreference(AppConstants.FILE_NAME_SHARED_PREFERENCES)
                .build()
    }
    override fun onCreate() {
        super.onCreate()
        component.inject(this)
        component.sharedPref().saveString("hello", "world")
        Log.i("test", component.sharedPref().getString("hello"))

    }
}

AppComponent.kt

@Singleton
@Component(modules = arrayOf(AndroidInjectionModule::class, ActivityBuilder::class, AppModuleBinds::class, AppModuleProvides::class))
interface AppComponent {

    @Component.Builder
    interface Builder {

        @BindsInstance
        fun application(application: Application): Builder

        @BindsInstance
        fun sharedPreference(@Named(Constant.Name.SHARED_PREFERENCES) sharedPreferenceName: String): Builder

        fun build(): AppComponent

    }

    fun inject(application: CoreApplication)

    fun sharedPref() : SharedPreferenceUtils

}

ActivityBuilder.kt

@Module
abstract class ActivityBuilder{
    @PerActivity
    @ContributesAndroidInjector(modules = arrayOf(HomeModuleBinds::class))
    abstract fun bindMainActivity(): MainActivity

    @PerActivity
    abstract fun dialogUtils() : DialogUtils

}

HomeModuleBinds.kt

@Module
    abstract class HomeModuleBinds {
        @Binds
        @PerActivity
        abstract fun activityContext(activity: Activity): Context

        @Binds
        @PerActivity
        abstract fun activity(activity: Activity): Activity
    }

DialogUtils.kt

@PerActivity
class DialogUtils @Inject constructor(var activity: Activity) {
    fun showDialog(error: String) = {
        val alertDialogBuilder = AlertDialog.Builder(activity)
        alertDialogBuilder.setTitle(error).create().show()

    }
}

有什么方法可以使用 dagger2 依赖循环在 MainActivity 中使用 DialogUtils 实例？

class MainActivity : AppCompatActivity() {

    @Inject
    @Singleton
    lateinit var sharedPref : SharedPreferenceUtils

    @Inject
    @PerActivity
    lateinit var dialogUtils: DialogUtils

    override fun onCreate(savedInstanceState: Bundle?) {
        AndroidInjection.inject(this)
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        sharedPref.saveString("test", "val")
        Log.i("test", sharedPref.getString("test"))



        //dialogUtils.showDialog("hello")
    }
}

例如，在 MainActivity 上为 DaggerUtils 使用 inject 会导致循环依赖错误

Answer 1

不要将 Activity 注入(inject) Utility 类。

然后在您的 Activity 调用中:

dialogUtils.showDialog( "hello", MyACtivity.this)

在 dialogUtils 中:

fun showDialog(error: String, context: Context) = {
        val alertDialogBuilder = AlertDialog.Builder(context)
        alertDialogBuilder.setTitle(error).create().show()

    }