datastore读取方式

https://blog.youkuaiyun.com/github_35581409/article/details/142901840

看到在datastore上存储自定义的可序列化的对象

之前项目中用到过datastore的preference，当时官网的介绍是这样的

https://developer.android.com/topic/libraries/architecture/datastore?hl=zh-cn#prefs-vs-proto

初始化

// At the top level of your kotlin file:
val Context.dataStore: DataStore<Preferences> by preferencesDataStore(name = "settings")

写入

suspend fun incrementCounter() {
  context.dataStore.edit { settings ->
    val currentCounterValue = settings[EXAMPLE_COUNTER] ?: 0
    settings[EXAMPLE_COUNTER] = currentCounterValue + 1
  }
}

读取

val EXAMPLE_COUNTER = intPreferencesKey("example_counter")
val exampleCounterFlow: Flow<Int> = context.dataStore.data
  .map { preferences ->
    // No type safety.
    preferences[EXAMPLE_COUNTER] ?: 0
}

读取的时候，返回flow对象，虽然说可以随时监听啊，但是我只要当前的值，不需要监听怎么办呢

  private suspend fun read(key: String): String? {
        val dataStoreKey = preferencesKey<String>(key)
        val preferences = dataStore.data.first()
        return preferences[dataStoreKey]
    }

直接返回first()就好了