android - Activity 在拆分屏幕后重新创建viewModel

Question

我有一个 Activity ，其中提供 View 抛出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)
        }

    }
}

Activity

    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，但是当我尝试进入拆分屏幕时，我的 Activity 将我传递给创建ViewModel的新实例。但是，当我关闭拆分屏幕并进入正常模式时，我的 Activity 将返回先前对ViewModel的检查。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

实际上，您不应该在ViewModel中设置onCreate()。

您可以立即设置它或使用惰性设置。

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

可以直接作为您 Activity 的成员之一。