Kotlin对SP使用的封装

为了更易于使用SharedPreferences，使用Koltin的委托模式来对SP进行封装

1. 定义委托类

class Preference<T>(val name: String, val default: T) {
    val prefs: SharedPreferences by lazy { MyApp.instance.applicationContext.getSharedPreferences("SP", Context.MODE_PRIVATE) }

    operator fun getValue(thisRef: Any?, property: KProperty<*>): T = getSharedPreferences(name, default)

    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T) = putSharedPreferences(name, value)


    private fun putSharedPreferences(name: String, value: T) = with(prefs.edit()) {
        when(value) {
            is Int -> putInt(name, value)
            is Float -> putFloat(name, value)
            is Long -> putLong(name, value)
            is Boolean -> putBoolean(name, value)
            is String -> putString(name, value)
            else -> throw IllegalArgumentException("SharedPreference can't be save this type")
        }.apply()
    }

    private fun getSharedPreferences(name:String, default: T): T = with(prefs) {
        val res: Any = when(default) {
            is Int -> getInt(name, default)
            is Float -> getFloat(name, default)
            is Long -> getLong(name, default)
            is Boolean -> getBoolean(name, default)
            is String -> getString(name, default)
            else -> throw IllegalArgumentException("SharedPreference can't be get this type")
        }
        return res as T
    }
}

2. 定义使用的静态方法

object DelegatesExt {
    fun <T> preference(name: String, default: T) = Preference(name, default)
}

3.简单使用

var mGuideEnable by DelegatesExt.preference("guide", false)