像对象一样操作SP

一、使用示例

class PreferenceManager {

    //用户id,
    var userId: String by PreferenceProxy("")

    var age: Int by PreferenceProxy(0)

    var isMan: Boolean  by PreferenceProxy(false)

    var floatValue: Float  by PreferenceProxy(0.0f)

    var doubleValue: Double by PreferenceProxy(0.0)

    var bean: Bean  by PreferenceProxy(Bean.empty())
}

App.preferenceManager .userId = "default userId"

val value=App.preferenceManager .userId

二、原理

var bean: Bean  by PreferenceProxy(Bean.empty())

/**
 * SP的属性代理
 */
class PreferenceProxy<T>(private val default: T) : ReadWriteProperty<Any?, T> {

    companion object {
        val context: Context by lazy {
            App.instance
        }
    }

    private val prefs by lazy {
        context.getSharedPreferences("xxxx", Context.MODE_PRIVATE)
    }

    private val gson by lazy {
        Gson()
    }

    private val map by lazy {
        HashMap<String, Any?>()
    }

    override fun getValue(thisRef: Any?, property: KProperty<*>): T = with(prefs) {
        val key = property.name
        //先取Map
        val mapValue = map[key]
        mapValue?.let {
            LogUtils.print("取Map:$key -> $it")
            return@with it as T
        }
        //Map没有，才去取SP
        when (default) {
            is Long -> {
                var it = getLong(key, default) as T
                LogUtils.print("取SP-Long：$key -> $it")
                //退出应用后，再次进来时，SP还有值，但是Map没有值了，所以需要在第一次取SP后，存到Map，以后就不用再取SP了
                map[key] = it
                return@with it
            }
            is String -> {
                var it = getString(key, default) as T
                LogUtils.print("取SP-String：$key -> $it")
                map[key] = it
                return@with it
            }
            is Float -> {
                var it = getFloat(key, default) as T
                LogUtils.print("取SP-Float：$key -> $it")
                map[key] = it
                return@with it
            }
            is Int -> {
                var it = getInt(key, default) as T
                LogUtils.print("取SP-Int：$key -> $it")
                map[key] = it
                return@with it
            }
            is Boolean -> {
                var it = getBoolean(key, default) as T
                LogUtils.print("取SP-Boolean：$key -> $it")
                map[key] = it
                return@with it
            }
            else -> {
                val jsonString = getString(key, null)
                if (jsonString != null) {

val preferenceManager: PreferenceManager by lazy {
            PreferenceManager()
        }

三、特别提醒