一、使用方法：

0、初始化实例：一般在EntryAbility.ts的onWindowStageCreate中初始化；（可忽略）

1、将数据写入Preferences实例

function() {
  let arrayNum: number[] = [1, 2, 3];
  let arrayStr: string[] = ["5", "2", "3"];
  let arrayBoo: boolean[] = [true, false, true];
  var fruit: Fruit;
  fruit = new Fruit();
  fruit.fruitName = "Name";
  fruit.fruitNum = "Num";
  PFUtils.put("number", 10);
  PFUtils.put("string", "22");
  PFUtils.put("boolean", true);
  PFUtils.put("arrayNum", arrayNum);
  PFUtils.put("arrayStr", arrayStr);
  PFUtils.put("arrayBoo", arrayBoo);
  PFUtils.put("fruit", fruit)  // 自定义实体
  this.breakpointSystem.register();
  this.intervalId = setInterval(this.countdown, 1000);
}

2、获取键对应的值

function() {
  PFUtils.get("number").then((value: number) => {
    Logger.error(Constants.TAG, "number：" + value)
  })
  PFUtils.get("string").then((value: string) => {
    Logger.error(Constants.TAG, "string：" + value)
  })
  PFUtils.get("boolean").then((value: boolean) => {
    Logger.error(Constants.TAG, "boolean：" + value)
  })
  PFUtils.get("arrayNum").then((value: Array<number>) => {
    Logger.error(Constants.TAG, "Array<number>：" + value)
  })
  PFUtils.get("arrayStr").then((value: Array<string>) => {
    Logger.error(Constants.TAG, "Array<string>：" + value)
  })
  PFUtils.get("arrayBoo").then((value: Array<boolean>) => {
    Logger.error(Constants.TAG, "Array<boolean>：" + value)
  })
  PFUtils.getEntity("fruit").then((value: Fruit) => {
    Logger.error(Constants.TAG, "Fruit：" + value)
    Logger.error(Constants.TAG, "FruitName：" + value.fruitName)
    Logger.error(Constants.TAG, "FruitNum：" + value.fruitNum)
  })
}

3、其他方法：

        1、getAll：获取含有所有键值的Object对象。

        2、has：检查Preferences实例是否包含名为给定Key的存储键值对

        3、delete：从Preferences实例中删除名为给定Key的存储键值对

        4、flush：将当前Preferences实例的数据异步存储到用户首选项的持久化文件中（put中已生效）

        5、clear：清除此Preferences实例中的所有存储

二、完整代码：

import dataPreferences from '@ohos.data.preferences';
import { Constants, Logger } from '@ohos/common';

let preference: dataPreferences.Preferences;
let preferenceTemp: dataPreferences.Preferences;
let context = getContext(this);

export class PFUtils {
  /**
   * Read the specified Preferences persistence file and load the data into the Preferences instance.
   */
  static async getPreferences(context: Context) {
    try {
      preference = await dataPreferences.getPreferences(context, Constants.PREFERENCES_NAME);
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to get preferences, Cause: ${err}`);
    }
  }

  /**
   * Deletes the specified Preferences persistence file from memory and removes the Preferences instance.
   */
  static async deletePreferences() {
    try {
      await dataPreferences.deletePreferences(context, Constants.PREFERENCES_NAME);
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to delete preferences, Cause: ${err}`);
    }
    preference = preferenceTemp;
  }

  /**
   * Save the data to the Preferences.
   *
   * @param data.
   */
  static async put(key: string, value: unknown) {
    if (!preference) {
      await this.getPreferences(getContext(this));
    }
    try {
      if (typeof value === "number") {
        await  preference.put(key, value);
      }
      if (typeof value === "string") {
        await  preference.put(key, value);
      }
      if (typeof value === "boolean") {
        await  preference.put(key, value);
      }
      if (typeof value === "object") {
        if (Array.isArray(value)) {
          await  preference.put(key, value);
        } else {
          await  preference.put(key, JSON.stringify(value));
        }
      }
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to put value, Cause: ${err}`);
    }
    // Store the Preference instance in the preference persistence file
    await preference.flush();
  }

  /**
   * Get preference data.
   */
  static async get(key: string) {
    let value: unknown;
    if (!preference) {
      await this.getPreferences(getContext(this));
    }
    try {
      value = await preference.get(key, undefined).then();
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to get value, Cause: ${err}`);
    }
    return value;
  }

  /**
   * Get custom entity data.
   */
  static async getEntity(key: string) {
    let value: string = '';
    if (!preference) {
      await this.getPreferences(getContext(this));
    }
    try {
      value = (await preference.get(key, '')).toString();
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to get value, Cause: ${err}`);
    }
    return JSON.parse(value);
  }

  /**
   * Get an Object object that contains all key values.
   */
  static async getAll() {
    let value: unknown;
    if (!preference) {
      await this.getPreferences(getContext(this));
    }
    try {
      value = await preference.getAll().then();
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to get value, Cause: ${err}`);
    }
    return value;
  }

  /**
   * Check if the Preferences instance contains a stored key value pair named the given Key
   */
  static async has(key: string) {
    let value: boolean = false;
    if (!preference) {
      await this.getPreferences(getContext(this));
    }
    try {
      value = await preference.has(key).then();
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to get value, Cause: ${err}`);
    }
    return value;
  }

  /**
   * Delete a stored key value pair named the given Key from the Preferences instance
   */
  static async delete(key: string) {
    if (!preference) {
      await this.getPreferences(getContext(this));
    }
    try {
      await preference.delete(key).then();
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to get value, Cause: ${err}`);
    }
  }

  /**
   * Clear all storage in this Preferences instance
   */
  static async clear() {
    if (!preference) {
      await this.getPreferences(getContext(this));
    }
    try {
      await preference.clear().then();
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to get value, Cause: ${err}`);
    }
  }

  /**
   *Asynchronous storage of data from the current Preferences instance to the persistent file of user preferences
   */
  static async flush() {
    if (!preference) {
      await this.getPreferences(getContext(this));
    }
    try {
      await preference.flush().then();
    } catch (err) {
      Logger.error(Constants.TAG, `Failed to get value, Cause: ${err}`);
    }
  }
}