android {
    ···
    dataBinding {
        enabled = true
    }
}
dependencies {
    ···
    implementation "androidx.fragment:fragment-ktx:$rootProject.fragmentVersion"
    implementation "androidx.lifecycle:lifecycle-extensions:$rootProject.lifecycleVersion"
    implementation "androidx.lifecycle:lifecycle-livedata-ktx:$rootProject.lifecycleVersion"
    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$rootProject.lifecycleVersion"
}

fragment_plant_detail.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>
        <variable
            name="viewModel"
            type="com.google.samples.apps.sunflower.viewmodels.PlantDetailViewModel" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            ···
            android:text="@{viewModel.plant.name}"/>

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

PlantDetailFragment.kt

class PlantDetailFragment : Fragment() {

    private val args: PlantDetailFragmentArgs by navArgs()
    private lateinit var shareText: String

    private val plantDetailViewModel: PlantDetailViewModel by viewModels {
        InjectorUtils.providePlantDetailViewModelFactory(requireActivity(), args.plantId)
    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val binding = DataBindingUtil.inflate<FragmentPlantDetailBinding>(
                inflater, R.layout.fragment_plant_detail, container, false).apply {
            viewModel = plantDetailViewModel
            lifecycleOwner = this@PlantDetailFragment
        }

        plantDetailViewModel.plant.observe(this) { plant ->
            // 更新相关 UI
        }

        return binding.root
    }
}

Plant.kt

data class Plant (
    val name: String
)

PlantDetailViewModel.kt

class PlantDetailViewModel(
    plantRepository: PlantRepository,
    private val plantId: String
) : ViewModel() {

    val plant: LiveData<Plant>

    override fun onCleared() {
        super.onCleared()
        viewModelScope.cancel()
    }

    init {
        plant = plantRepository.getPlant(plantId)
    }
}

PlantDetailViewModelFactory.kt

class PlantDetailViewModelFactory(
    private val plantRepository: PlantRepository,
    private val plantId: String
) : ViewModelProvider.NewInstanceFactory() {

    @Suppress("UNCHECKED_CAST")
    override fun <T : ViewModel> create(modelClass: Class<T>): T {
        return PlantDetailViewModel(plantRepository, plantId) as T
    }
}

InjectorUtils.kt

object InjectorUtils {
    private fun getPlantRepository(context: Context): PlantRepository {
        ···
    }

    fun providePlantDetailViewModelFactory(
        context: Context,
        plantId: String
    ): PlantDetailViewModelFactory {
        return PlantDetailViewModelFactory(getPlantRepository(context), plantId)
    }
}

Android常用应用架构

Android

MVC

MVP

Android MVP 快速集成框架

MVVM-Jetpack

Navigation

Data Binding

ViewModelsa & LiveData

Lifecycle

Room

Paging

WorkManger

Jetpack

架构

使用示例

CATALOG

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