{"id":291309,"date":"2018-10-24T21:05:02","date_gmt":"2018-10-24T17:05:02","guid":{"rendered":"http:\/\/savepearlharbor.com\/?p=291309"},"modified":"-0001-11-30T00:00:00","modified_gmt":"2018-10-24T17:05:02","slug":"","status":"publish","type":"post","link":"https:\/\/savepearlharbor.com\/?p=291309","title":{"rendered":"Android LiveData \u043d\u0430 Kotlin \u0441 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435\u043c Retrofit \u0438 coroutines"},"content":{"rendered":"\n
\u0421\u0442\u0430\u0442\u044c\u044f \u0440\u0430\u0441\u0441\u043a\u0430\u0437\u044b\u0432\u0430\u0435\u0442 \u043e\u0431 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0438 Android Components<\/abbr> ViewModel, LifeCycle \u0438 LiveData. \u042d\u0442\u0438 \u043a\u043e\u043c\u043f\u043e\u043d\u0435\u043d\u0442\u044b \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0442 \u043d\u0435 \u0437\u0430\u0431\u043e\u0442\u0438\u0442\u044c\u0441\u044f \u043e \u0436\u0438\u0437\u043d\u0435\u043d\u043d\u043e\u043c \u0446\u0438\u043a\u043b\u0435 Activity.
\u0422\u0430\u043a \u0436\u0435 \u0440\u0430\u0441\u0441\u043c\u043e\u0442\u0440\u0435\u043d \u043f\u0440\u0438\u043c\u0435\u0440 \u043f\u0440\u0438\u043c\u0435\u043d\u0435\u043d\u0438\u044f \u0441\u043e\u0432\u0440\u0435\u043c\u0435\u043d\u043d\u043e\u0433\u043e Coroutines<\/abbr> \u0432 \u0441\u0432\u044f\u0437\u043a\u0435 \u0441 \u0440\u0435\u043f\u043e\u0437\u0438\u0442\u0430\u0440\u0438\u0435\u043c \u043d\u0430 Retrofit <\/p>\n
fun main(args: Array<String>): Unit = runBlocking {     \/\/ Wait (suspend) for Result     val result: Result<User> = api.getUser(\"username\").awaitResult()     \/\/ Check result type     when (result) {         \/\/Successful HTTP result         is Result.Ok -> saveToDb(result.value)         \/\/ Any HTTP error         is Result.Error -> log(\"HTTP error with code ${result.error.code()}\", result.error)         \/\/ Exception while request invocation         is Result.Exception -> log(\"Something broken\", e)     } } <\/code><\/pre>\n
  <\/a><\/p>\n
  Retrofit coroutines extension<\/b>
  kotlin-coroutines-retrofit<\/a>
  \u0420\u0430\u0441\u0448\u0438\u0440\u0435\u043d\u0438\u0435 \u0434\u043b\u044f Retrofit \u043d\u0430 Kotlin. \u042d\u0442\u043e \u0432\u0441\u0435\u0433\u043e \u0434\u0432\u0430 \u0444\u0430\u0439\u043b\u0430. \u042f \u043f\u0440\u043e\u0441\u0442\u043e \u0434\u043e\u0431\u0430\u0432\u0438\u043b \u0438\u0445 \u0432 \u043f\u0440\u043e\u0435\u043a\u0442. \u0412\u044b \u043c\u043e\u0436\u0435\u0442\u0435 \u043f\u043e\u0434\u043a\u043b\u044e\u0447\u0438\u0442\u044c \u0438\u0445 \u0447\u0435\u0440\u0435\u0437 Dependency \u0432 Gradle. \u041d\u0430 Github \u0435\u0441\u0442\u044c \u043f\u0440\u0438\u043c\u0435\u0440\u044b \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u044f.
  \u0422\u0430\u043a\u0436\u0435 \u043f\u043e\u0434\u043a\u043b\u044e\u0447\u0430\u0435\u043c Adapter addCallAdapterFactory(CoroutineCallAdapterFactory())<\/i>.
  ServerAPI \u0438 Repository \u043d\u0430\u0445\u043e\u0434\u044f\u0442\u0441\u044f \u0432 \u043e\u0434\u043d\u043e\u043c \u0444\u0430\u0439\u043b\u0435<\/p>\n
  REST API<\/b>
  \u0420\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0435\u0439 REST API \u043d\u0430 Kotlin. \u041e\u043d\u0430 \u043d\u0435 \u0438\u043c\u0435\u0435\u0442 \u043a\u0430\u043a\u0438\u0445 \u043b\u0438\u0431\u043e \u0441\u043f\u0435\u0446\u0438\u0444\u0438\u0447\u043d\u044b\u0445 \u0438\u0437\u043c\u0435\u043d\u0435\u043d\u0438\u0439  <\/p>\n
ServerAPI<\/b><\/p>\n
\n
import android.arch.lifecycle.MutableLiveData import android.util.Log import com.jakewharton.retrofit2.adapter.kotlin.coroutines.experimental.CoroutineCallAdapterFactory import kotlinx.coroutines.experimental.android.UI import kotlinx.coroutines.experimental.async import retrofit2.Retrofit import retrofit2.converter.gson.GsonConverterFactory import okhttp3.OkHttpClient import okhttp3.logging.HttpLoggingInterceptor import retrofit2.Call import retrofit2.http.* import ru.gildor.coroutines.retrofit.Result import ru.gildor.coroutines.retrofit.awaitResult  object ServerAPI {      var API_BASE_URL: String = getNetworkHost();     var httpClient = OkHttpClient.Builder().addInterceptor(         HttpLoggingInterceptor().apply {             level = if (BuildConfig.DEBUG) HttpLoggingInterceptor.Level.BODY else HttpLoggingInterceptor.Level.NONE         })      var builder: Retrofit.Builder = Retrofit.Builder()             .baseUrl(API_BASE_URL)             .addCallAdapterFactory(CoroutineCallAdapterFactory())             .addConverterFactory(GsonConverterFactory.create())      var retrofit = builder             .client(httpClient.build())             .build()      var netService = retrofit.create<NetService>(         NetService::class.java!!)      interface NetService {         @GET(\"api\/stores\")         fun getStoreAll(@Header(\"Authorization\") bearer: String): Call<Array<Store>>     } } <\/code><\/pre>\n
  <\/div>\n<\/div>\n
  LiveData<\/b>
  \u0414\u0430\u043b\u0435\u0435 \u0440\u0430\u0441\u0441\u043c\u043e\u0442\u0440\u0438\u043c Repository. \u042d\u0442\u043e \u043e\u0441\u043d\u043e\u0432\u043d\u043e\u0439 \u0441\u0435\u0440\u0432\u0438\u0441 \u043f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u044f LiveData. \u0418\u043d\u0438\u0446\u0438\u0430\u043b\u0438\u0437\u0438\u0440\u0443\u0435\u043c LiveData \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435\u043c \u0437\u0430\u0433\u0440\u0443\u0437\u043a\u0438: Resource.loading(null)<\/i>. \u0414\u0430\u043b\u0435\u0435 \u043e\u0436\u0438\u0434\u0430\u0435\u043c \u043e\u043a\u043e\u043d\u0447\u0430\u043d\u0438\u0435 \u0437\u0430\u043f\u0440\u043e\u0441\u0430 awaitResult()<\/i> \u042d\u0442\u043e\u0442 \u0432\u044b\u0437\u043e\u0432 \u0434\u043e\u043b\u0436\u0435\u043d \u0431\u044b\u0442\u044c \u0432 \u0431\u043b\u043e\u043a\u0435 Coroutin async(UI)<\/i>
  \u041f\u043e \u043e\u043a\u043e\u043d\u0447\u0430\u043d\u0438\u044e \u0437\u0430\u043f\u0440\u043e\u0441\u0430 \u043c\u044b \u043c\u043e\u0436\u0435\u043c \u0445\u044d\u043d\u0434\u043b\u0438\u0442\u044c \u0440\u0435\u0437\u0443\u043b\u044c\u0442\u0430\u0442. \u0415\u0441\u043b\u0438 \u0432\u0441\u0435 \u0445\u043e\u0440\u043e\u0448\u043e \u0440\u0435\u0437\u0443\u043b\u044c\u0442\u0430\u0442 \u0431\u0443\u0434\u0435\u0442 \u0441\u043e\u0445\u0440\u0430\u043d\u0435\u043d \u0432 mutableLiveData.value = Resource.success(result.value)<\/i> \u0412\u0430\u0436\u043d\u044b\u0439 \u043c\u043e\u043c\u0435\u043d\u0442 \u2014 \u044d\u0442\u043e \u0434\u043e\u043b\u0436\u0435\u043d\u0430 \u0431\u044b\u0442\u044c \u0441\u0441\u044b\u043b\u043a\u0430 \u043d\u0430 \u043d\u043e\u0432\u044b\u0439 \u044d\u043a\u0437\u044d\u043c\u043f\u043b\u044f\u0440, \u0438\u043d\u0430\u0447\u0435 observer LiveData \u043d\u0435 \u043e\u0442\u0440\u0430\u0431\u043e\u0442\u0430\u0435\u0442. see: new Resource<>(SUCCESS, data, null);<\/i>  <\/p>\n
Repository<\/b><\/p>\n
\n
   class Repository {      fun getStores(token: String)  :  MutableLiveData<Resource<Array<Store>>>{         val mutableLiveData = MutableLiveData<Resource<Array<Store>>>()         mutableLiveData.value = Resource.loading(null)         val req = PostsAPI.netService.getStoreAll(token)          try {             async(UI) {                 val result = req.awaitResult()                 \/\/ Check result type                 when (result) {                     \/\/Successful HTTP result                     is Result.Ok -> {                         mutableLiveData.value = Resource.success(result.value)                     }                     \/\/ Any HTTP error                     is Result.Error -> {                         mutableLiveData.value  = Resource.error(\"Http Error!\", null)                     }                     \/\/ Exception while request invocation                     is Result.Exception -> Log.d(TAG, result.exception.message)                 }             }         } catch (e: Exception) {             Log.d(TAG, e.toString())         }         return mutableLiveData     } }      <\/code><\/pre>\n
  <\/div>\n<\/div>\n
  Wrapper data<\/b>
  \u0414\u043b\u044f \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0438 \u043e\u0448\u0438\u0431\u043e\u043a \u0438 \u043f\u0435\u0440\u0435\u0434\u0430\u0447\u0438 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u044f \u0432 Fragment \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u0442\u0441\u044f Wrapper \u2014 Resource<T><\/i>. 
  \u041e\u043d \u0445\u0440\u0430\u043d\u0438\u0442\u044c \u0442\u0440\u0438 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u044f:  <\/p>\n
public enum Status { SUCCESS, ERROR, LOADING }<\/code><\/pre>\n
  C\u0430\u043c\u0438 \u0434\u0430\u043d\u043d\u044b\u0435:  <\/p>\n
@Nullable public final T data;<\/code><\/pre>\n
  <\/p>\n
Resource<T><\/b><\/p>\n
A generic class that contains data and status about loading this data<\/a>   <\/p>\n
\/\/ A generic class that contains data and status about loading this data. public class Resource<T> {     @NonNull public final Status status;     @Nullable public final T data;     @Nullable public final String message;     private Resource(@NonNull Status status, @Nullable T data,             @Nullable String message) {         this.status = status;         this.data = data;         this.message = message;     }      public static <T> Resource<T> success(@NonNull T data) {         return new Resource<>(Status.SUCCESS, data, null);     }      public static <T> Resource<T> error(String msg, @Nullable T data) {         return new Resource<>(Status.ERROR, data, msg);     }      public static <T> Resource<T> loading(@Nullable T data) {         return new Resource<>(Status.LOADING, data, null);     }      public enum Status { SUCCESS, ERROR, LOADING } }       <\/code><\/pre>\n
  <\/div>\n<\/div>\n
  ViewModel<\/b>
  StoresViewModel \u0437\u0430\u043f\u0440\u0430\u0448\u0438\u0432\u0430\u0435\u0442 \u0434\u0430\u043d\u043d\u044b\u0435 \u0443 \u0440\u0435\u043f\u043e\u0437\u0438\u0442\u043e\u0440\u0438\u044f \u0438 \u0441\u043e\u0445\u0440\u0430\u043d\u044f\u0435\u0442 \u0432\u043e \u0432\u043d\u0443\u0442\u0440\u0435\u043d\u043d\u0435\u0439 \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u043e\u0439 stores<\/i>  <\/p>\n
val api = Repository() stores = api.getStores(token) <\/code><\/pre>\n
  <\/p>\n
ViewModel<\/b><\/p>\n
\n
class StoresViewModel (context: Context, token: String) : ViewModel() {     val stores: MutableLiveData<Resource<Array<Store>>>     init {         val api = Repository()         stores = api.getStores(token)     } }       <\/code><\/pre>\n
  <\/div>\n<\/div>\n
  ViewModelProviders<\/b>
  \u0414\u043b\u044f \u043f\u0435\u0440\u0435\u0434\u0430\u0447\u0438 \u043f\u0430\u0440\u0430\u043c\u0435\u0442\u0440\u043e\u0432 \u0432 ViewModel \u0440\u0430\u0441\u0448\u0438\u0440\u0438\u043c \u0441\u0442\u0430\u043d\u0434\u0430\u0440\u0442\u043d\u0443\u044e ViewModelProviders<\/i>
  \u041d\u0430\u043f\u0440\u0438\u043c\u0435\u0440 \u0434\u043b\u044f \u043f\u0435\u0440\u0435\u0434\u0430\u0447\u0438 \u0432 LoginViewModel<\/i> \u043d\u0430\u0434\u043e \u0434\u0432\u0430 \u043f\u0430\u0440\u0430\u043c\u0435\u0442\u0440\u0430 (Login,Password). \u0414\u043b\u044f \u043f\u0435\u0440\u0435\u0434\u0430\u0447\u0438 \u0442\u043e\u043a\u0435\u043d\u0430 \u0432 StoresViewModel<\/i> \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u0442\u0441\u044f \u043e\u0434\u0438\u043d (Token)  <\/p>\n
AppViewModelFactory<\/b><\/p>\n
\n
class AppViewModelFactory(private val contect: Context, vararg params: Any) :     ViewModelProvider.NewInstanceFactory() {     private val mParams: Array<out Any>      init {         mParams = params     }      override fun <T : ViewModel> create(modelClass: Class<T>): T {         return if (modelClass == LoginViewModel::class.java) {             LoginViewModel(contect, mParams[0] as String, mParams[1] as String) as T         } else if (modelClass == StoresViewModel::class.java) {             StoresViewModel(contect, mParams[0] as String) as T         } else {             super.create(modelClass)         }     } }       <\/code><\/pre>\n
  <\/div>\n<\/div>\n
  Fragment<\/b>
  \u041f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u0435 StoresViewModel:  <\/p>\n
viewModel = ViewModelProviders.of(this, AppBuyViewModelFactory(requireActivity(), tokenHolder.token)).get(StoresViewModel::class.java) <\/code><\/pre>\n
  \u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u043d\u0430\u0431\u043b\u044e\u0434\u0430\u0442\u0435\u043b\u044f Observer \u0437\u0430 \u0438\u0437\u043c\u0435\u043d\u0435\u043d\u0438\u0435\u043c \u0434\u0430\u043d\u043d\u044b\u0445:  <\/p>\n
 \/\/ Observe data on the ViewModel, exposed as a LiveData  viewModel.stores.observe(this, Observer<Resource<Array<Store>>> { storesResource -> <\/code><\/pre>\n
  <\/p>\n
Fragment<\/b><\/p>\n
\n
    override fun onCreateView(         inflater: LayoutInflater, container: ViewGroup?,         savedInstanceState: Bundle?     ): View? {         val view = inflater.inflate(R.layout.stores_fragment, container, false)          val tokenHolder = TokenHolder(PreferenceManager.getDefaultSharedPreferences(requireActivity()))          viewModel = ViewModelProviders.of(this, AppViewModelFactory(requireActivity(), tokenHolder.token)).get(StoresViewModel::class.java)          recyclerView = view.findViewById<RecyclerView>(R.id.store_list).apply {             setHasFixedSize(true)         }         return view     }       override fun onActivityCreated(savedInstanceState: Bundle?) {         super.onActivityCreated(savedInstanceState)          \/\/ Observe data on the ViewModel, exposed as a LiveData         viewModel.stores.observe(this, Observer<Resource<Array<Store>>> { storesResource ->              val stores = storesResource?.data             stores?.let {                 viewAdapter = StoresAdapter(stores!!)                 recyclerView.adapter = viewAdapter             }              if (storesResource?.status  == Resource.LOADING){                 log(\"Loading...\")             }              if (storesResource?.status  == Resource.ERROR){                 log(\"Error : \" + storesResource?.message)             }          })     }       <\/code><\/pre>\n
  <\/div>\n<\/div>\n
  P.S.<\/p>\n
  \u0414\u043b\u044f \u0445\u0440\u0430\u043d\u0435\u043d\u0438\u044f Token \u0438 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u044f \u0435\u0433\u043e \u0432\u043e \u0432\u0441\u0435\u043c \u043f\u0440\u0438\u043b\u043e\u0436\u0435\u043d\u0438\u0438 \u044f \u043f\u0440\u0438\u043c\u0435\u043d\u0438\u043b \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0443\/\u0440\u0430\u0441\u0448\u0438\u0440\u0435\u043d\u0438\u0435 \u043e\u0442 Fabio Collini. \u041f\u0440\u0438\u043c\u0435\u043d\u0435\u043d\u0438\u0435 \u0445\u043e\u0440\u043e\u0448\u043e \u043e\u043f\u0438\u0441\u0430\u043d\u043e \u0432 \u0435\u0433\u043e \u0441\u0442\u0430\u0442\u044c\u0435. \u0421\u0441\u044b\u043b\u043a\u0430 \u0435\u0441\u0442\u044c \u043d\u0430 \u0441\u0442\u0440\u0430\u043d\u0438\u0446\u0435 \u0432 Github \u0438\u043b\u0438 \u043d\u0438\u0436\u0435 \u0432 \u044d\u0442\u043e\u0439 \u0441\u0442\u0430\u0442\u044c\u0435.
  prefs-delegates by Fabio Collini<\/a><\/p>\n
class TokenHolder(prefs: SharedPreferences) {     var token by prefs.string()         private set      var count by prefs.int()         private set      fun saveToken(newToken: String) {         token = newToken         count++     } } <\/code><\/pre>\n
  Gradle<\/b>  <\/p>\n
    implementation 'android.arch.lifecycle:extensions:1.1.1'     implementation \"org.jetbrains.kotlinx:kotlinx-coroutines-core:0.30.0\"     implementation \"org.jetbrains.kotlinx:kotlinx-coroutines-android:0.30.0\"     implementation \"com.squareup.retrofit2:retrofit:2.4.0\"     implementation \"com.squareup.retrofit2:converter-gson:2.4.0\"     implementation \"com.jakewharton.retrofit:retrofit2-kotlin-coroutines-experimental-adapter:1.0.0\"     \/\/ If you use Kotlin 1.2 or 1.3     \/\/ compile 'ru.gildor.coroutines:kotlin-coroutines-retrofit:0.13.0'     \/\/ compile 'ru.gildor.coroutines:kotlin-coroutines-retrofit:0.13.0-eap13' <\/code><\/pre>\n
  Links<\/b>
  \u0412\u0441\u0435 \u0432 \u043e\u0434\u043d\u043e\u043c \u043f\u0440\u0438\u043c\u0435\u0440\u0435
  github.com\/googlesamples\/android-sunflower<\/a><\/p>\n
  Android Architecture Components samples
  github.com\/googlesamples\/android-architecture-components<\/a><\/p>\n
  LiveData Overview
  developer.android.com\/topic\/libraries\/architecture\/livedata#kotlin<\/a><\/p>\n
  Async code using Kotlin Coroutines
  proandroiddev.com\/async-code-using-kotlin-coroutines-233d201099ff<\/a><\/p>\n
  Multithreading and Kotlin
  medium.com\/@korhanbircan\/multithreading-and-kotlin-ac28eed57fea<\/a><\/div>\n