如何在Android中在不同的类之间共享数值？

huangapple
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英文:

How to share values between different classes in Android?

问题

目前，我正在开发一个应用程序，在这个应用程序中，我需要保存不同类型的数据值，并在需要时从多个类中访问这些数据。目前，我正在使用对象（单例）类来实现这一点，就像下面这样：

  1. object VLineDataHolder {
  2.     private val _logsProgress = MutableStateFlow(0)
  3.     val logsProgress: StateFlow<Int>
  4.         get() = _logsProgress
  5.     fun setLogsProgress(logsProgress: Int) {
  6.         _logsProgress.value = logsProgress
  7.     }
  8. }

我不确定我是否正在以正确的方式处理这个问题，实际上我不需要在用户退出应用程序后保留数据，这就是为什么我没有在这里使用 DataStore 或 SharedPreferences。是否有人可以解释这是否是一个好的解决方案？

英文:

Currently I am developing an app where I have to save values of different types of data and access the data from multiple classes when needed. Currently I am using Object(singleton) classes for that. like below:

  1.     object VLineDataHolder {
  2.         private val _logsProgress = MutableStateFlow(0)
  3.         val logsProgress: StateFlow&lt;Int&gt;
  4.             get() = _logsProgress
  5.         fun setLogsProgress(logsProgress: Int) {
  6.             _logsProgress.value = logsProgress
  7.         }
  8.     }

I am just not sure If I am doing it in a right way, I don't actually need to persist the data after user exits the app that's why I am not using any DataStore or SharedPreferences here. Can any one explain if it is the good solution or not?

答案1

得分: 1

你可以在单例类内部使用可变的共享流（MutableSharedFlow），创建一种类似总线（Bus）的模式。只需将数据推送到流中，然后从任何位置观察它。例如，当用户登录事件发生时，我想被通知。

  1. object EventBusKotlin {
  3.     private val _events = MutableSharedFlow<AuthEvents>()
  4.     val events = _events.asSharedFlow()
  6.     suspend fun publish(event: AuthEvents) {
  7.         _events.emit(event)
  8.     }
  10.     @OptIn(DelicateCoroutinesApi::class)
  11.     suspend inline fun <reified T> subscribe(crossinline onEvent: (T) -> Unit) {
  12.         events.filterIsInstance<T>()
  13.             .collectLatest { event ->
  14.                 coroutineContext.ensureActive()
  15.                 onEvent(event)
  16.             }
  17.     }
  19. }
  21. sealed class AuthEvents
  23. data class LoginEvent(
  24.     val userId: String,
  25.     val userName: String
  26. ): AuthEvents()
  28. // 观察/订阅事件
  30. @Inject
  31. lateinit var eventBus: EventBusKotlin
  33. // 推送/发布事件
  34. suspend fun postLoginEvent(loginEvent: LoginEvent) {
  35.     eventBus.publish(loginEvent)
  36. }
  38. // 订阅和监听最新事件
  39. fun subscribeLoginEvent(lifecycleOwner: LifecycleOwner) {
  40.     lifecycleOwner.lifecycleScope.launch {
  41.         eventBus.subscribe<AuthEvents> { event ->
  43.             when (event) {
  44.                 is LoginEvent -> Log.d(
  45.                     "LoginEventHandler",
  46.                     "${event.userName} 登录成功"
  47.                 )
  48.             }
  50.         }
  51.     }
  52. }
英文:

You can use mutuable shared flow inside singleton class and creating a Bus type pattern. Just push the data and observe it from anywhere. As example I want to be noticed whenever use login event happens

  1. object EventBusKotlin {
  3. private val _events = MutableSharedFlow&lt;AuthEvents&gt;()
  4. val events = _events.asSharedFlow()
  6. suspend fun publish(event: AuthEvents) {
  7.     _events.emit(event)
  8. }
  10. @OptIn(DelicateCoroutinesApi::class)
  11. suspend inline fun &lt;reified T&gt; subscribe(crossinline onEvent: (T) -&gt; Unit) {
  12.     events.filterIsInstance&lt;T&gt;()
  13.         .collectLatest { event -&gt;
  14.             coroutineContext.ensureActive()
  15.             onEvent(event)
  16.         }
  17. }
  19. }
  21. sealed class AuthEvents

Event model

  1. data class LoginEvent(
  2. val userId: String,
  3. val userName: String
  4. ):AuthEvents()

Observing/Subscribing

  1. @Inject
  2. lateinit var eventBus: EventBusKotlin
  4.   //push/publish event
  5.   suspend fun postLoginEvent(loginEvent: LoginEvent) {
  6.      eventBus.publish(loginEvent)
  7.  } 
  9. // subscribing and listening latest event
  10. fun subscribeLoginEvent(lifecycleOwner: LifecycleOwner) {
  11.     lifecycleOwner.lifecycleScope.launch {
  12.         eventBus.subscribe&lt;AuthEvents&gt; { event -&gt;
  14.             when (event) {
  15.                 is LoginEvent -&gt; Log.d(
  16.                     &quot;LoginEventHandler&quot;,
  17.                     &quot;${event.userName} logged-in successfully&quot;
  18.                 )
  19.             }
  21.         }
  22.     }
  23. }

huangapple
  • 本文由 发表于 2023年3月1日 15:32:51
  • 转载请务必保留本文链接：https://go.coder-hub.com/75600693.html
  • android
  • datastore
  • kotlin
  • sharedpreferences
  • singleton
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