活动在分屏后重新创建viewModel

Question

我有一个 Activity，我在其中提供 view throw ViewModelFactory

ViewModelFactory

@Singleton
class ViewModelFactory @Inject constructor(private val creators: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>) : ViewModelProvider.Factory {
    override fun <T : ViewModel> create(modelClass: Class<T>): T {
        var creator: Provider<out ViewModel>? = creators.get(modelClass)
        if (creator == null) {
            for (entry in creators.entries) {
                if (modelClass.isAssignableFrom(entry.key)) {
                    creator = entry.value
                    break
                }
            }
        }
        if (creator == null) {
            throw IllegalArgumentException("unknown model class $modelClass")
        }
        try {
            return creator.get() as T
        } catch (e: Exception) {
            Log.d("ERRORR", e.toString())
            throw RuntimeException(e)
        }

    }
}

活动

    class MyActivity: AppCompatActivity(), Injectable, HasSupportFragmentInjector {
        @Inject
        lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Fragment>

    lateinit var viewModel: MyViewModel

        @Inject
        lateinit var viewModelFactory: ViewModelFactory

        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)

            viewModel = ViewModelProviders.of(this, viewModelFactory).get(MyViewModel::class.java)
            val binding: MyLayoutBinding= DataBindingUtil.setContentView(this, R.layout.my_layout)
        }
}

一切正常，但是当我尝试进入分屏时，我的活动让我进入创建 ViewModel 的新实例。但是当我关闭分屏并进入正常模式时，我的活动会返回我的 ViewModel 的先前检查。哪里有问题？

@Module
abstract class ActivityModule {

    @Binds
    abstract fun activity(activity: MainActivity): Activity

    @Binds
    abstract fun bindViewModelFactory(factory: MyViewModelFactory): ViewModelProvider.Factory

    @Binds
    @IntoMap
    @ViewModelKey(MainViewModel::class)
    abstract fun MyViewModel(mainViewModel: MyViewModel): ViewModel



}

Answer 1

确实，您不应该将ViewModel 设置为onCreate()。

您可以立即设置或使用惰性设置。

private val viewModel: MyViewModel by lazy {
  ViewModelProviders.of(this, viewModelFactory).get(MyViewModel::class.java)
}

那，直接作为你的 Activity 的成员之一。