Kotlin 属性代理 + SharePreference

最新推荐文章于 2023-07-12 21:53:29 发布

小码农·李

最新推荐文章于 2023-07-12 21:53:29 发布

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分类专栏： Kotlin Android 文章标签： android

本文链接：https://blog.youkuaiyun.com/qq_24523279/article/details/115168159

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该博客介绍了一种使用Kotlin委托属性简化SharedPreferences的方法，通过`PreferenceDelegate`类实现对SharedPreference的读写操作。只需一行代码即可完成设置和获取，支持多种数据类型，并提供了清除偏好设置的功能。

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“一行代码” 搞定 SharePreference

private var isBlockAll: Boolean by PreferenceDelegate(SpConstant.SP_BLOCK_ALL, false) //屏蔽所有

//打印值
loggerd("isBlockAll: $isBlockAll")
if (isBlockAll) {
	...
} else {
	...
}

哇，一行代码，感觉针不错！现在你就可以操作Sp存储的字段了

具体实现代码


import android.content.Context
import android.content.SharedPreferences
import com.guagua.sing.SingApplication
import com.guagua.sing.constant.SpConstant
import java.io.ByteArrayInputStream
import java.io.ByteArrayOutputStream
import java.io.ObjectInputStream
import java.io.ObjectOutputStream
import java.net.URLDecoder
import java.net.URLEncoder
import kotlin.reflect.KProperty

/**
 * Copyright (C), 2020-2021
 * @author lxc
 * Date: 2021/3/23 20:55
 * Version: 1.0.0
 * Description: kotlin委托属性+SharedPreference管理本地变量
 * History:
 * <author> <time> <version> <desc>
 */
class PreferenceDelegate<T>(val name: String, private val default: T) {
    companion object {
        private const val file_name = SpConstant.SP_NAME

        private val prefs: SharedPreferences by lazy {
	        //使用上下文获取sp实例
            App.getInstance().applicationContext.getSharedPreferences(file_name, Context.MODE_PRIVATE)
        }

        fun clearPreference() {
            prefs.edit().clear().apply()
        }

        fun clearPreference(key: String) {
            prefs.edit().remove(key).apply()
        }

        fun contains(key: String): Boolean = prefs.contains(key)

        fun getAll(): Map<String, *> = prefs.all
    }

    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 Long -> putLong(name, value)
            is Int -> putInt(name, value)
            is Boolean -> putBoolean(name, value)
            is Float -> putFloat(name, value)
            is String -> putString(name, value)
            else -> putString(name, serialize(value))
        }.apply()
    }

    private fun<A> serialize(obj: A): String {
        val byteArrayOutputStream = ByteArrayOutputStream()
        val objectOutputStream = ObjectOutputStream(byteArrayOutputStream)
        objectOutputStream.writeObject(obj)
        var result = byteArrayOutputStream.toString("ISO-8859-1")
        result =URLEncoder.encode(result, "UTF-8")
        objectOutputStream.close()
        byteArrayOutputStream.close()
        return result
    }

    private fun getSharedPreferences(name: String, default: T): T = with(prefs) {
        val res = when (default) {
            is Long -> getLong(name, default)
            is String -> getString(name, default)
            is Int -> getInt(name, default)
            is Boolean -> getBoolean(name, default)
            is Float -> getFloat(name, default)
            else -> deSerialization(getString(name, serialize(default)))
        }
        return res as T
    }

    private fun <A> deSerialization(str: String?): A {
        val redStr = URLDecoder.decode(str, "UTF-8")
        ObjectInputStream(ByteArrayInputStream(redStr.toByteArray(charset("ISO-8859-1")))).use {
            return it.readObject() as A
        }
    }
}