Dagger 2：如何从 FragmentFactory 的子组件绑定父组件中的 Fragment Map

我有这个 Dagger 2 配置：

应用程序组件.kt

@Singleton
@Component(
    modules = [
        AndroidSupportInjectionModule::class,
        AppModule::class,
        ActivityBindingModule::class,
    ]
)
interface AppComponent : AndroidInjector<AppApplication> {
    @Component.Builder
    abstract class Builder : AndroidInjector.Builder<AppApplication>()
}

ActivityBindingModule.kt

@Module
abstract class ActivityBindingModule {
    @ActivityScoped
    @ContributesAndroidInjector(
        modules = [
            MainActivityModule::class,
            FragmentModule::class //a fragment factory for each activity
        ]
    )
    internal abstract fun mainActivity(): MainActivity
}

MainActivityModule.kt

@Module(subcomponents = [LoginFragmentSubcomponent::class])
abstract class MainActivityModule {
    //uncommenting this works fine but Fragment can't be scoped
    //@Binds
    //@IntoMap
    //@FragmentKey(LoginFragment::class)
    //abstract fun bindLoginFragment(loginFragment: LoginFragment): Fragment

    //...other things which work fine
}

@Subcomponent(modules = [LoginFragmentModule::class])
@FragmentScoped
interface LoginFragmentSubcomponent : AndroidInjector<LoginFragment> {
    @Subcomponent.Builder
    abstract class Builder : AndroidInjector.Builder<LoginFragment>()
}

@Module
abstract class LoginFragmentModule {
    //this can't be seen from Map used in DefaultFragmentFactory
    @Binds
    @IntoMap
    @FragmentKey(LoginFragment::class)
    abstract fun bindLoginFragment(loginFragment: LoginFragment): Fragment
}

片段模块.kt

@Module
abstract class FragmentModule {
    @Binds
    internal abstract fun bindFragmentFactory(factory: DefaultFragmentFactory): FragmentFactory
}

默认FragmentFactory.kt

@ActivityScoped
class DefaultFragmentFactory @Inject constructor(
    private val creators: Map<Class<out Fragment>, @JvmSuppressWildcards Provider<Fragment>>
) : FragmentFactory() {
    //this is deprecated in fragment-ktx 1.1.0-alpha06 
    //but you need to override this if you were using the bundle
    override fun instantiate(classLoader: ClassLoader, className: String, args: Bundle?): Fragment {
        return instantiate(classLoader, className).apply { arguments = args }
    }
    override fun instantiate(classLoader: ClassLoader, className: String): Fragment {
        val fragmentClass = loadFragmentClass(classLoader, className)
        val found = creators.entries.find { fragmentClass.isAssignableFrom(it.key) }
        val provider = found?.value
        //if we don't find a match in the map, proceed with the default empty constructor
        return if (provider != null) {
            provider.get()
        } else {
            fragmentClass.newInstance()
        }
    }
}

我在这里想做的是使用FragmentFactory来创建Fragments。 如代码中所述，我可以取消注释此行：

@Binds
@IntoMap
@FragmentKey(LoginFragment::class)
abstract fun bindLoginFragment(loginFragment: LoginFragment): Fragment

并删除所有连接到LoginFragmentSubcomponent并且注射工作正常。

这种方法的问题是 Fragment 无法正确确定作用域，如果 Fragment 被销毁，下面的所有子 Fragments 都会被销毁，这将迫使 Factory 在下一次调用时创建一个新实例。

所以我决定添加一个Subcomponent调用 LoginFragmentSubcomponent 能够定义@FragmentScoped在上面。 现在的问题是从模块LoginFragmentModule我无法为父母做出贡献Map我需要在DefaultFragmentFactory其类型为：

Map<Class<out Fragment>, @JvmSuppressWildcards Provider<Fragment>>

事实上，我在编译时收到的错误是：

[Dagger/MissingBinding] 
java.util.Map<java.lang.Class<? extends androidx.fragment.app.Fragment>,
javax.inject.Provider<androidx.fragment.app.Fragment>> cannot be provided 
without an @Provides-annotated method.

这里有一个具有可重现问题的示例存储库: https://github.com/matpag/dagger-test-fragmentfactory https://github.com/matpag/dagger-test-fragmentfactory

有针对这个的解决方法吗？

使用匕首2.21

提前致谢

PS：这背后的想法FragmentFactory注射来自于此 很棒的帖子：https://www.captechconsulting.com/blogs/using-androidxs-fragmentfactory-with-dagger-for-fragment-dependency-injection https://www.captechconsulting.com/blogs/using-androidxs-fragmentfactory-with-dagger-for-fragment-dependency-injection我只是稍微调整了一下。