Kotlin 封装万能SharedPreferences存取任何类型详解

/**
 * author: smart
 * time: 2016/10/26
 * 封装好SharedPreferences 并使用 序列化和反序列化来存储数据
 * 注意要在全局环境使用
 */
class Preference<T>(val context : Context,val name : String,val default : T) : ReadWriteProperty<Any?,T>{

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


  override fun getValue(thisRef: Any?, property: KProperty<*>): T {
    return findPreference(name,default)
  }

  override fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
    putPreference(name,value)
  }

  /**
   * 查找数据 返回给调用方法一个具体的对象
   * 如果查找不到类型就采用反序列化方法来返回类型
   * default是默认对象 以防止会返回空对象的异常
   * 即如果name没有查找到value 就返回默认的序列化对象，然后经过反序列化返回
   */
  private fun <A> findPreference(name :String,default: A) : A = with(prefs){
    val res : Any = 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)))
    }
    res as A
  }

  private fun <A> putPreference(name :String,value: A) = with(prefs.edit()){
    when(value){
      is Long -> putLong(name,value)
      is String -> putString(name,value)
      is Int -> putInt(name,value)
      is Boolean -> putBoolean(name,value)
      is Float -> putFloat(name,value)
      else -> putString(name,serialize(value))
    }.apply()

  }

  /**
   * 删除全部数据
   */
  fun clearPreference(){
    prefs.edit().clear().commit()
  }

  /**
   * 根据key删除存储数据
   */
  fun clearPreference(key : String){
    prefs.edit().remove(key).commit()
  }

  /**
   * 序列化对象

   * @param person
   * *
   * @return
   * *
   * @throws IOException
   */
  @Throws(IOException::class)
  private fun<A> serialize(obj: A): String {
    val byteArrayOutputStream = ByteArrayOutputStream()
    val objectOutputStream = ObjectOutputStream(
        byteArrayOutputStream)
    objectOutputStream.writeObject(obj)
    var serStr = byteArrayOutputStream.toString("ISO-8859-1")
    serStr = java.net.URLEncoder.encode(serStr, "UTF-8")
    objectOutputStream.close()
    byteArrayOutputStream.close()
    return serStr
  }

  /**
   * 反序列化对象

   * @param str
   * *
   * @return
   * *
   * @throws IOException
   * *
   * @throws ClassNotFoundException
   */
  @Throws(IOException::class, ClassNotFoundException::class)
  private fun<A> deSerialization(str: String): A {
    val redStr = java.net.URLDecoder.decode(str, "UTF-8")
    val byteArrayInputStream = ByteArrayInputStream(
        redStr.toByteArray(charset("ISO-8859-1")))
    val objectInputStream = ObjectInputStream(
        byteArrayInputStream)
    val obj = objectInputStream.readObject() as A
    objectInputStream.close()
    byteArrayInputStream.close()
    return obj
  }
}

 var save : LoginSaveBean by Preference<LoginSaveBean>(App.getInstance(),Constant.LOCAL_SAVE_LOGIN_MODEL_KEY, LoginSaveBean("0","0"))