Android-ViewModel.pdf

Androd TipTip
2018. 11. 25(Sun) Introduction in Android AAC-ViewModel

1. Android ViewModel Command + B৬ ೣԋ Tae-hwan
2. ࣗѐ • GDG Seoul ਍৔૓ • ٘۽੉٘ ա੉எ ਍৔૓ • RGP Korea • ਃӝਃ উ٘۽੉٘ ѐߊ • Blog : Է ݆਷ ѐߊ੗о غ ੗! (https://thdev.tech)
3. য়ט ঌইࠅ ղਊ • MVVM • AAC-ViewModel • AAC-ViewModel ղࠗ ௏٘ ࢓ಝࠁӝ
4. ViewModel vs AAC-ViewModel
5. ViewModel vs AAC-ViewModel ViewModel ୡӝച ߂ ࢎਊ ৘ AAC-ViewModel ୡӝച ߂ ࢎਊ ৘
6. ViewModel
7. ViewModel ੜ ঌӝ • ViewModel ҳઑ ঌӝ • ViewModelਸ ٜ݅ӝ ਤೠ بҳ • ViewModelਸ ੜ ഝਊೞӝ ਤೠ ܻ࠙ • ܻ࠙ೞ׮ ࠁݶ ࢤӝח Ҋ޹ • ؊ ա਷ ViewModel
8. ViewModel View Model DataBinding and commands ViewModel updates the model Send notifications Send notifications ViewModel ҳઑ ঌӝ
9. ViewModelਸ ٜ݅ӝ ਤೠ بҳ • View ViewModel р੄ ҙ҅ܳ ױ੺ दఃӝ ਤೠ ݾ੸ • DI(Dagger, koin) ഝਊೞৈ Ѿ೤بܳ ઴ੋ׮. • DataBinding ഝਊਵ۽ View৬੄ ੄ઓبܳ ઴ੋ׮.
10. ViewModelਸ ੜ ഝਊೞӝ ਤೠ ܻ࠙ • ViewModelҗ Model਷ ৉ೡী ٮۄ ୭؀ೠ ܻ࠙ೠ׮ • ܻ࠙ೡ ࣻ ੓ח ೠ ୭؀۽ ܻ࠙ೞৈ, ৮੹ೠ Factory pattern ୶ҳ
11. ܻ࠙ೞ׮ ࠁݶ ࢤӝח Ҋ޹ • അप਷ DataBinding੄ Ѿ೤بо ֫ইઉ ৮੹ೠ ഋకܳ ٜ݅ӝ औ૑ ঋ׮ • ழझథ ࠭৬ DataBindingਸ ୭؀ೠ ഝਊೞח ഋక۽ ࢸ҅ೡ ೙ਃо ੓׮
12. ؊ ա਷ ViewModel • ղࠗীࢲ ࢎਊೞח Rx/Coroutines ١ਸ ਤೠ ۄ੉೐ ࢎ੉௿ਸ ٮܰب۾ ࢸ҅ೡ ೙ਃо ੓׮ • ૒੽ Lifecycle ଻ਊೞח ഋక۽ ѐߊ ೙ਃ • AAC-ViewModelਸ ഝਊೞѢա
13. Jetpack AAC-ViewModel
14. ViewModel = / AAC-ViewModel
16. AAC-ViewModel ݾ੸ • The ViewModel class is designed to store and manage UI-related data in a lifecycle conscious way. The ViewModel class allows data to survive configuration changes such as screen rotations. • Android AAC ViewModel਷ ചݶ ഥ੹ द ؘ੉ఠܳ ਬ૑ೡ ࣻ ੓ח ҳઑ۽ ٣੗ੋೞ৓ਵݴ, Android Lifecycle੄ onDestroy() ௏٘о ز੘ೠ׮. https://developer.android.com/topic/libraries/architecture/viewmodel
17. AAC-ViewModel ੿ܻೞݶ • ݾ੸ : ചݶ ഥ੹ द ؘ੉ఠ ਬ૑ܳ ਤೠ ҳઑ۽ ViewModelਸ ٣੗ੋ • Activity/Fragment੄ Lifecycleী ٮۄ ViewModel ਬ૑ܳ ೞҊ ੓׮. • ղࠗীࢲ Lifecycleਸ ࢎਊೡ ࣻ ੓ب۾ ୡӝചೞҊ ੓ਵݴ, onDestroy() ز੘ द ViewModel ղ ࠗ੄ onCleared() ഐ୹ਸ ా೧ Releaseܳ ਬبೠ׮.
18. AAC-ViewModel != ViewModel
19. AAC-ViewModel • AAC ViewModel਷ Androidীࢲ ࢎਊ਷ оמೞ૑݅ • MSDN੄ ViewModelҗח ইޖ ࢚ҙহҊ, Ӓր ੉ܴ ݅ ViewModel੐ਸ ঌҊ о੗ • উ٘۽੉٘ ѐߊ ಞ੄ࢿਸ ୶ҳೞח ViewModel ੿ب۽ ౵ঈೞ੗ • ಞ੄࢚ Application ઱ੑ੉ оמೞҊ • ಞ੄࢚ AAC-ViewModel਷ ؘ੉ఠ ਬ૑ب ೧ળ׮
20. Jetpack AAC-ViewModel ౵೧஖ӝ
21. AAC-ViewModel • AAC-ViewModel਷ ইې 2ѐ۽ ࢚ࣘ߉ই ҳഅೠ׮ • ViewModel() • AndroidViewModel(application)
22. AAC-ViewModel class SharedViewModel : ViewModel() { val selected = MutableLiveData<Item>() fun select(item: Item) { selected.value = item } }
23. AAC-ViewModel ୡӝച • AAC-ViewModel ୡӝചח ViewModelProviders۽ ୡӝചೠ׮ • Activity/Fragment 2ѐ ઺ী ೞա۽ ୡӝച оמ • ӝࠄ ViewModel ࢤࢿ੗ ߧਤܳ ߩযաݶ Factoryܳ ࢚ࣘ߉ই ߹ب ҳഅ೧ঠ ೠ׮
24. AAC-ViewModel class MasterFragment : Fragment() { private lateinit var itemSelector: Selector private lateinit var model: SharedViewModel override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) model = activity?.run { ViewModelProviders.of(this).get(SharedViewModel::class.java) } ?: throw Exception("Invalid Activity") itemSelector.setOnClickListener { item -> // Update the UI } } } ViewModelProviders.of(this)
25. ViewModelProviders.of(this) • thisী Activity/Fragment۽੄ ୡӝചо оמ • Activity ࢎਊ द Activity Lifecycleਸ ٮܲ׮ • Fragment ࢎਊ द Fragment Lifecycleਸ ٮܲ׮
26. of ղࠗܳ ࠁ੗
27. ViewModelProviders.of(this) ӝࠄ ੿੄ @NonNull @MainThread public static ViewModelProvider of(@NonNull Fragment fragment) { return of(fragment, null); } @NonNull @MainThread public static ViewModelProvider of(@NonNull FragmentActivity activity) { return of(activity, null); }
28. ViewModelProviders.of(this) Factory ੿੄ @NonNull @MainThread public static ViewModelProvider of(@NonNull Fragment fragment, @Nullable Factory factory) { Application application = checkApplication(checkActivity(fragment)); if (factory == null) { factory = ViewModelProvider.AndroidViewModelFactory.getInstance(application); } return new ViewModelProvider(fragment.getViewModelStore(), factory); } @NonNull @MainThread public static ViewModelProvider of(@NonNull FragmentActivity activity, @Nullable Factory factory) { Application application = checkApplication(activity); if (factory == null) { factory = ViewModelProvider.AndroidViewModelFactory.getInstance(application); } return new ViewModelProvider(activity.getViewModelStore(), factory); } fragment.getViewModelStore() activity.getViewModelStore() ViewModelStore()ܳ ా೧ ӝઓ ViewModel ࢤࢿ ؘ੉ఠо թওח૑ ୓௼ ViewModelStore()ܳ ా೧ ӝઓ ViewModel ࢤࢿ ؘ੉ఠо թওח૑ ୓௼
29. Fragment.java @NonNull @Override public ViewModelStore getViewModelStore() { if (getContext() == null) { throw new IllegalStateException("Can't access ViewModels from detached fragment"); } if (mViewModelStore == null) { mViewModelStore = new ViewModelStore(); } return mViewModelStore; }
30. FragmentActivity.java @NonNull @Override public ViewModelStore getViewModelStore() { if (getApplication() == null) { throw new IllegalStateException("Your activity is not yet attached to the " + "Application instance. You can't request ViewModel before onCreate call."); } if (mViewModelStore == null) { NonConfigurationInstances nc = (NonConfigurationInstances) getLastNonConfigurationInstance(); if (nc != null) { // Restore the ViewModelStore from NonConfigurationInstances mViewModelStore = nc.viewModelStore; } if (mViewModelStore == null) { mViewModelStore = new ViewModelStore(); } } return mViewModelStore; }
31. ViewModelStore.java package androidx.lifecycle; public class ViewModelStore { private final HashMap<String, ViewModel> mMap = new HashMap<>(); final void put(String key, ViewModel viewModel) { ViewModel oldViewModel = mMap.put(key, viewModel); if (oldViewModel != null) { oldViewModel.onCleared(); } } final ViewModel get(String key) { return mMap.get(key); } /** * Clears internal storage and notifies ViewModels that they are no longer used. */ public final void clear() { for (ViewModel vm : mMap.values()) { vm.onCleared(); } mMap.clear(); } }
32. ѾҴ • ViewModelStore.java • ActivityFragment.java/Fragment.javaীࢲ ViewModelStore.javaܳ о૑Ҋ੓׮. • Activity/Fragmentীࢲ ೙ਃೠ ViewModelStoreܳ HashMapਵ۽ ࠁҙೞҊ, ੉ܳ оઉৡ׮
33. ୡӝച ௏٘۽
34. AAC-ViewModel class MasterFragment : Fragment() { private lateinit var itemSelector: Selector private lateinit var model: SharedViewModel override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) model = activity?.run { ViewModelProviders.of(this).get(SharedViewModel::class.java) } ?: throw Exception("Invalid Activity") itemSelector.setOnClickListener { item -> // Update the UI } } } ViewModelProviders.of(this) get(SharedViewModel::class.java)
35. get(SharedViewModel::class.java) • Activity/Fragmentীࢲ ࠁҙ ઺ੋ ViewModelStore ё୓ܳ ੉ਊೞৈ getਸ ୊ܻ • getীࢲח ࢜۽਍ ё୓ܳ ࢤࢿೞѢա, ViewModelStoreী ӝઓ ё୓ܳ ׮द ࠛ۞ৡ׮ • HashMapী ੷੢ೞӝ ਤೠ Ҋਬఃܳ ੿੄ೠ׮.
36. get(Class<T>) / Ҋਬః @NonNull @MainThread public <T extends ViewModel> T get(@NonNull Class<T> modelClass) { String canonicalName = modelClass.getCanonicalName(); if (canonicalName == null) { throw new IllegalArgumentException("Local and anonymous classes can not be ViewModels"); } return get(DEFAULT_KEY + ":" + canonicalName, modelClass); } private static final String DEFAULT_KEY = "androidx.lifecycle.ViewModelProvider.DefaultKey"; Default৬ canonicalNameਸ ೤୛ Ҋਬః ࢤࢿ Package name.SharedViewModel
37. get(Key, Class<T>) @NonNull @MainThread public <T extends ViewModel> T get(@NonNull String key, @NonNull Class<T> modelClass) { ViewModel viewModel = mViewModelStore.get(key); if (modelClass.isInstance(viewModel)) { //noinspection unchecked return (T) viewModel; } else { //noinspection StatementWithEmptyBody if (viewModel != null) { // TODO: log a warning. } } viewModel = mFactory.create(modelClass); mViewModelStore.put(key, viewModel); //noinspection unchecked return (T) viewModel; } ViewModelStore۽ࠗఠ getValue viewModel੉ null੉ ইפݶ return null੉ݶ ViewModelFactory۽ࠗఠ new Factoryח ӝࠄ ViewModelFactory ੿੄о ઓ੤ ViewModelStoreী put
38. ViewModelFactory
39. ViewModelFactory @NonNull @MainThread public static ViewModelProvider of(@NonNull Fragment fragment, @Nullable Factory factory) { Application application = checkApplication(checkActivity(fragment)); if (factory == null) { factory = ViewModelProvider.AndroidViewModelFactory.getInstance(application); } return new ViewModelProvider(fragment.getViewModelStore(), factory); } @NonNull @MainThread public static ViewModelProvider of(@NonNull FragmentActivity activity, @Nullable Factory factory) { Application application = checkApplication(activity); if (factory == null) { factory = ViewModelProvider.AndroidViewModelFactory.getInstance(application); } return new ViewModelProvider(activity.getViewModelStore(), factory); } fragment.getViewModelStore() activity.getViewModelStore() Factory ੿੄ܳ ೞ૑ ঋਵݶ AndroidViewModelFactoryࢎਊ Factory ੿੄ܳ ೞ૑ ঋਵݶ AndroidViewModelFactoryࢎਊ if (factory == null) { factory = ViewModelProvider.AndroidViewModelFactory.getInstance(application); } if (factory == null) { factory = ViewModelProvider.AndroidViewModelFactory.getInstance(application); }
40. ViewModelFactory Application ೞա݅ ੓ਸ ҃਋ /** * {@link Factory} which may create {@link AndroidViewModel} and * {@link ViewModel}, which have an empty constructor. */ public static class AndroidViewModelFactory extends ViewModelProvider.NewInstanceFactory { private static AndroidViewModelFactory sInstance; /** * Retrieve a singleton instance of AndroidViewModelFactory. * * @param application an application to pass in {@link AndroidViewModel} * @return A valid {@link AndroidViewModelFactory} */ @NonNull public static AndroidViewModelFactory getInstance(@NonNull Application application) { if (sInstance == null) { sInstance = new AndroidViewModelFactory(application); } return sInstance; } private Application mApplication; /** * Creates a {@code AndroidViewModelFactory} * * @param application an application to pass in {@link AndroidViewModel} */ public AndroidViewModelFactory(@NonNull Application application) { mApplication = application;
41. ViewModelFactory ࢤࢿ੗о হח ҃਋ public static class NewInstanceFactory implements Factory { @SuppressWarnings("ClassNewInstance") @NonNull @Override public <T extends ViewModel> T create(@NonNull Class<T> modelClass) { //noinspection TryWithIdenticalCatches try { return modelClass.newInstance(); } catch (InstantiationException e) { throw new RuntimeException("Cannot create an instance of " + modelClass, e); } catch (IllegalAccessException e) { throw new RuntimeException("Cannot create an instance of " + modelClass, e); } } }
42. ViewModelFactory ழझథ ࢤࢿ੗о ੓׮ݶ? class SharedViewModelFactory(data data data) : ViewModelProvider.Factory { override fun <T : ViewModel?> create(modelClass: Class<T>): T { return SharedViewModel(data, data, data) as T } } ViewModelProviders.of(this, SharedViewModelFactory(data, data, data)).get(SharedViewModel::class.java)
43. ViewModel ࢤࢿ ৮ܐ
44. ঱ઁ destroy ೡө?
45. ViewModel clear • ঱ઁ AAC-ViewModel੉ clear ೡө? • Activity/Fragment੄ Lifecycleੋ onDestroy()ীࢲ ഛੋ оמ
46. FragmentActivity.java /** * Destroy all fragments. */ @Override protected void onDestroy() { super.onDestroy(); if (mViewModelStore != null && !isChangingConfigurations()) { mViewModelStore.clear(); } mFragments.dispatchDestroy(); }
47. FragmentActivity.java /** * Called when the fragment is no longer in use. This is called * after {@link #onStop()} and before {@link #onDetach()}. */ @CallSuper public void onDestroy() { mCalled = true; FragmentActivity activity = getActivity(); boolean isChangingConfigurations = activity != null && activity.isChangingConfigurations(); if (mViewModelStore != null && !isChangingConfigurations) { mViewModelStore.clear(); } }
48. ViewModelStore.java /** * Clears internal storage and notifies ViewModels that they are no longer used. */ public final void clear() { for (ViewModel vm : mMap.values()) { vm.onCleared(); } mMap.clear(); }
49. ViewModel.java public abstract class ViewModel { /** * This method will be called when this ViewModel is no longer used and will be destroyed. * <p> * It is useful when ViewModel observes some data and you need to clear this subscription to * prevent a leak of this ViewModel. */ @SuppressWarnings("WeakerAccess") protected void onCleared() { } }
50. ViewModel = / AAC-ViewModel
51. AAC-ViewModel ঱ઁ ਬਊೞѱ ࢎਊೡө?
52. ਬਊೠ ViewModel? • Activity੄ ചݶ ഥ੹ द ؘ੉ఠ ਬ૑о ೙ਃೠ ҃਋ ਬਊೞ׮. • 1ѐ੄ Activityীࢲ ׮઺੄ Fragmentীࢲ زੌೠ ੉߮౟/ؘ੉ఠܳ ୊ܻೞҊ रਸ ҃਋ • onClearedীࢲ releaseо ೙ਃೞ׮
53. 1ѐ੄ Activityীࢲ ׮઺੄ Fragment • Fragmentীࢲ fragmentо ইצ activityܳ ֈѹળ׮. • ViewModelProviders.of(activity).get(SharedViewModel::class.java)
54. RxJava disposable abstract class BaseViewModel : ViewModel() { val disposable: CompositeDisposable = CompositeDisposable() override fun onCleared() { super.onCleared() disposable.clear() } }
55. Coroutines cancel abstract class BaseViewModel : ViewModel(), CoroutineScope { val job: Job = Job() override val coroutineContext: CoroutineContext get() = Dispatchers.Default + job override fun onCleared() { super.onCleared() job.cancel() } }
56. хࢎ೤פ׮ taehwan@thdev.net