如何从 AbstractSavedStateViewModelFactory 动态设置包

Question

我的视图模型工厂：

class ViewModelFactory @Inject constructor(
    private val viewModelMap: MutableMap<Class<out ViewModel>, ViewModelAssistedFactory<out ViewModel>>,
    owner: SavedStateRegistryOwner,
    defaultArgs: Bundle?
) : AbstractSavedStateViewModelFactory(owner, defaultArgs) {

    @Throws(IllegalStateException::class)
    @Suppress("UNCHECKED_CAST")
    override fun <T : ViewModel?> create(key: String, modelClass: Class<T>, handle: SavedStateHandle): T {
        return viewModelMap[modelClass]?.create(handle) as? T ?: throw IllegalStateException("Unknown ViewModel class")
    }
}

活动：

@Inject
lateinit var viewModelFactory: ViewModelFactory
protected val viewModel: ViewModel by lazy { ViewModelProvider(this, viewModelFactory).get(getViewModelClass()) }

视图模型：

@AssistedInject.Factory
interface Factory : ViewModelAssistedFactory<SplashViewModel>

我想知道如何动态提供 defaultArgs 而不是：

活动模块

@Module
    companion object {
        @JvmStatic
        @Nullable
        @Provides
        fun provideDefaultArgs(): Bundle? {
            return null
        }
    }

这个想法是能够向 ViewModel 发送一个参数，比如说 DetailActivity 的 ID。通常我使用“init”方法，但如果我可以使用StateHandle map会更好。像这样和这样的东西。

说得通？是否可以？

Answer 1

我遇到了两种解决方案：

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方案一：

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将我们的 ViewModelFactory 更改为：

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class ViewModelFactory @Inject constructor(\n    private val viewModelMap: MutableMap<Class<out ViewModel>, ViewModelAssistedFactory<out ViewModel>>\n) {\n    fun create(owner: SavedStateRegistryOwner, defaultArgs: Bundle? = null): AbstractSavedStateViewModelFactory {\n        return object : AbstractSavedStateViewModelFactory(owner, defaultArgs) {\n            @Suppress("UNCHECKED_CAST")\n            override fun <T : ViewModel?> create(key: String, modelClass: Class<T>, handle: SavedStateHandle): T {\n                return viewModelMap[modelClass]?.create(handle) as? T ?: throw IllegalStateException("Unknown ViewModel class")\n            }\n        }\n    }\n}\n

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最后：

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@Inject\nlateinit var viewModelFactory: ViewModelFactory\nprotected val viewModel: ViewModel by lazy { ViewModelProvider(this, viewModelFactory.create(this, args).get(getViewModelClass()) }\n

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另外，我们可以将 ActivityModule 简化为（示例）：

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@AssistedModule\n@Module(includes = [AssistedInject_SplashActivityModule::class])\nabstract class SplashActivityModule{\n\n    @Binds\n    @IntoMap\n    @ViewModelKey(SplashViewModel::class)\n    abstract fun bindFactory(factory: SplashViewModel.Factory): ViewModelAssistedFactory<out ViewModel>\n}\n

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Tom\xc3\xa1\xc5\xa1 Mlynari\xc4\x8d的这篇文章帮助解决了这个问题。

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方案B：

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创建一个Factory没有注入依赖项的：

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class ViewModelFactoryAlt<out V : ViewModel>(\n    private val viewModelFactory: ViewModelAssistedFactory<V>,\n    owner: SavedStateRegistryOwner,\n    defaultArgs: Bundle? = null\n) : AbstractSavedStateViewModelFactory(owner, defaultArgs) {\n\n    @Suppress("UNCHECKED_CAST")\n    override fun <T : ViewModel> create(key: String, modelClass: Class<T>, handle: SavedStateHandle): T {\n        return viewModelFactory.create(handle) as T\n    }\n}\n

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创建我们的ViewModelAssitedFactory喜欢：

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class HelloWorldViewModelFactory @Inject constructor(\n    private val dependencyA: DependencyA,\n    ...\n) : ViewModelAssistedFactory<HelloWorldViewModel> {\n    override fun create(stateHandle: SavedStateHandle): HelloWorldViewModel {\n        return HelloWorldViewModel(stateHandle, dependencyA, ...)\n    }\n}\n

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最后：

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@Inject\nlateinit var factory: HelloWorldViewModelFactory\nprivate val viewModel: HelloWorldViewModel by viewModels { ViewModelFactoryAlt(factory, this, intent.extras) }\n

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这篇文章由埃莱帮助解决了这个问题。

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