android - @Inject 设置不注入(inject)属性

Question

我正在尝试使用 Android Dagger ‡ implementation并将 DispatchingAndroidInjector 注入(inject)到我的 Application 类中:

class MyApp : Application(), HasActivityInjector {

    private lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Activity>
        @Inject set    

    override fun onCreate() {
        super.onCreate()
        AppInjector.init(this)
    }

    override fun activityInjector(): ActivityInjector<Activity> {
        return dispatchingAndroidInjector
    }

}

但我收到一个 IllegalArgumentExecption 声明“lateinit 属性尚未初始化”:

06-19 10:57:30.773 10797-10797/com.example.app E/AndroidRuntime: FATAL EXCEPTION: main
        Process: com.example.app, PID: 10797
        java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.app/com.example.app.ui.MainActivity}: kotlin.UninitializedPropertyAccessException: lateinit property dispatchingAndroidInjector has not been initialized
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2666)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2727)
            at android.app.ActivityThread.-wrap12(ActivityThread.java)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1478)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:154)
            at android.app.ActivityThread.main(ActivityThread.java:6121)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)
         Caused by: kotlin.UninitializedPropertyAccessException: lateinit property dispatchingAndroidInjector has not been initialized
            at com.example.app.MyApp.activityInjector(MyApp.kt:28)
            at dagger.android.AndroidInjection.inject(AndroidInjection.java:55)
            at com.example.app.injection.AppInjector.handleActivity(AppInjector.kt:41)
            at com.example.app.injection.AppInjector.access$handleActivity(AppInjector.kt:14)
            at com.example.app.injection.AppInjector$init$1.onActivityCreated(AppInjector.kt:21)
            at android.app.Application.dispatchActivityCreated(Application.java:197)
            at android.app.Activity.onCreate(Activity.java:961)
            at android.support.v4.app.BaseFragmentActivityGingerbread.onCreate(BaseFragmentActivityGingerbread.java:54)
            at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:319)
            at com.example.app.ui.MainActivity.onCreate(MainActivity.kt:20)
            at android.app.Activity.performCreate(Activity.java:6682)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2619)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2727) 
            at android.app.ActivityThread.-wrap12(ActivityThread.java) 
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1478) 
            at android.os.Handler.dispatchMessage(Handler.java:102) 
            at android.os.Looper.loop(Looper.java:154) 
            at android.app.ActivityThread.main(ActivityThread.java:6121) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)

这是用于创建 AppComponent 并注入(inject) MyApp 依赖项的 AppInjector 类:

object AppInjector {

    fun init(app: MyApp) {
        DaggerAppComponent.builder().application(app).build().inject(app)
        // ...
    }

}

和 AppComponent 接口(interface):

@Singleton
@Component(modules = arrayOf(
    AndroidInjectionModule::class,
    AppModule::class,
    MainActivityModule::class
)) interface AppComponent {

    @Component.Builder interface Builder {

        @BindsInstance fun application(app: Application): Builder

        fun build(): AppComponent

    }

    fun inject(app: MyApp)

}

我在属性访问器上使用了 @Inject 注释，如 the documentation 中所述。 ，但它似乎没有用。我做错了什么？

Answer 1

我现在无法测试，但我认为这是因为您的属性(property)是私有(private)的。 Dagger 不使用反射，因此它注入(inject)的字段必须从类外部可见才能运行。

(显式写出 set 对此没有帮助，因为在这种情况下它只代表一个私有(private) setter。请注意，所有属性的字段都是私有(private)的，非私有(private)属性有 getters/适当时具有更广泛可见性的 setter 。)

您还应该能够只注释属性而不是它的 setter ，所以这将是最终结果:

@Inject
lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Activity>

如果您希望您的属性是私有(private)的，请考虑改用构造函数注入(inject)。