HarmonyOS 鸿蒙Next 首选项dataPreferences实例的通用读写

HarmonyOS 鸿蒙Next 首选项dataPreferences实例的通用读写 我看了SetAppFontSize这个第一课里的示例代码，想把首选项改为通用，但没有成功，请各位老师指点，感谢！

import dataPreferences from '@ohos.data.preferences';
import { GlobalContext } from '../utils/GlobalContext';
import Logger from '../utils/Logger';

const TAG = '[PreferencesUtil]';
const PREFERENCES_NAME = 'myPreferences';

export class PreferencesUtil {
  createMyPreferences(context: Context) {
    let myPreferences: Function = (() => {
      let preferences: Promise<dataPreferences.Preferences> = dataPreferences.getPreferences(context, PREFERENCES_NAME);
      return preferences;
    });
    GlobalContext.getContext().setObject('getMyPreferences', myPreferences);
  }

  saveDefaultPreferences(PreferenceKey: string, PreferenceValue: string) {
    let getMyPreferences: Function = GlobalContext.getContext().getObject(PreferenceKey) as Function;
    getMyPreferences().then(async (preferences: dataPreferences.Preferences) => {
      await preferences.put(PreferenceKey, PreferenceValue);
      preferences.flush();
    }).catch((err: Error) => {
      Logger.error(TAG, 'Get the preferences failed, err: ' + err);
    });
  }

  saveChangePreferences(PreferenceKey: string, PreferenceValue: string) {
    let getMyPreferences: Function = GlobalContext.getContext().getObject(PreferenceKey) as Function;
    getMyPreferences().then(async (preferences: dataPreferences.Preferences) => {
      await preferences.put(PreferenceKey, PreferenceValue);
      preferences.flush();
    }).catch((err: Error) => {
      Logger.error(TAG, 'put the preferences failed, err: ' + err);
    });
  }

  async getChangePreferences(PreferenceKey: string) {
    let PreferenceValue: string = '';
    let getMyPreferences: Function = GlobalContext.getContext().getObject(PreferenceKey) as Function;
    PreferenceValue = await (await getMyPreferences()).get(PreferenceKey);
    return PreferenceValue;
  }

  async deleteChangePreferences(PreferenceKey: string) {
    let getMyPreferences: Function = GlobalContext.getContext().getObject(PreferenceKey) as Function;
    const preferences: dataPreferences.Preferences = await getMyPreferences();
    let deleteValue = preferences.delete(PreferenceKey);
    deleteValue.then(() => {
      Logger.info(TAG, 'Succeeded in deleting the key appFontSize.');
    }).catch((err: Error) => {
      Logger.error(TAG, 'Failed to delete the key appFontSize. Cause: ' + err);
    });
  }
}

export default new PreferencesUtil();

export default class EntryAbility extends UIAbility {
  onCreate(want: Want, launchParam: AbilityConstant.LaunchParam) {
    Logger.info(TAG, 'onCreate');
    GlobalContext.getContext().setObject('abilityWant', want);
    PreferencesUtil.createMyPreferences(this.context);
    PreferencesUtil.saveDefaultPreferences('appFontSize', CommonConstants.SET_SIZE_NORMAL.toString());
  }
}

import router from '@ohos.router';
import SettingItemComponent from '../view/SettingItemComponent';
import TitleBarComponent from '../view/TitleBarComponent';
import HomeViewModel from '../viewmodel/HomeViewModel';
import CommonConstants from '../common/constants/CommonConstants';
import StyleConstants from '../common/constants/StyleConstants';
import Logger from '../common/utils/Logger';
import PreferencesUtil from '../common/database/Preferencesutil';
import SettingData from '../viewmodel/SettingData';

const TAG = '[HomePage]';

@Component
struct HomePage {
  private settingArr = HomeViewModel.initSettingData();
  @State changeFontSize: number = CommonConstants.SET_SIZE_NORMAL;

  onPageShow() {
    PreferencesUtil.getChangePreferences('appFontSize').then(value => {
      this.changeFontSize = value;
      Logger.info(TAG, 'Get the value of changeFontSize: ' + this.changeFontSize);
    });
  }

  build() {
    Column() {
      TitleBarComponent({ isBack: false, title: $r('app.string.home_title') })

      Row() {
        SettingItemComponent({
          setting: this.settingArr[CommonConstants.DISPLAY_INDEX],
          changeFontSize: this.changeFontSize.toString(),
          itemClick: () => {}
        })
      }
      .blockBackground(StyleConstants.BLOCK_TOP_MARGIN_FIRST_PERCENT)

      Row() {
        SettingItemComponent({
          setting: this.settingArr[CommonConstants.VOICE_INDEX],
          changeFontSize: this.changeFontSize.toString(),
          itemClick: () => {}
        })
      }
      .blockBackground(StyleConstants.BLOCK_TOP_MARGIN_SECOND_PERCENT)

      Row() {
        this.SettingItems()
      }
      .blockBackground(StyleConstants.BLOCK_TOP_MARGIN_SECOND_PERCENT)
    }
    .backgroundColor($r('sys.color.ohos_id_color_sub_background'))
    .width(StyleConstants.FULL_WIDTH)
    .height(StyleConstants.FULL_HEIGHT)
  }

  @Builder SettingItems() {
    List() {
      ForEach(this.settingArr.slice(CommonConstants.START_INDEX, CommonConstants.END_INDEX),
        (item: SettingData, index?: Number) => {
        ListItem() {
          SettingItemComponent({ setting: item, changeFontSize: this.changeFontSize.toString(), itemClick: () => {
            if (index === CommonConstants.SET_FONT_INDEX) {
              router.pushUrl({
                url: CommonConstants.SET_URL
              }).catch((error: Error) => {
                Logger.info(TAG, 'HomePage push error' + JSON.stringify(error));
              });
            }
          } })
        }
      }, (item: SettingData) => JSON.stringify(item))
    }
    .divider({
      strokeWidth: $r('app.float.setting_item_divider_width'),
      color: $r('app.color.setting_item_divider'),
      startMargin: $r('app.float.setting_item_divider_start_margin'),
      endMargin: StyleConstants.DIVIDER_END_MARGIN_PERCENT
    })
  }
}

@Extend(Row) function blockBackground(marginTop: string) {
  .backgroundColor(Color.White)
  .borderRadius($r('app.float.block_background_radius'))
  .margin({ top: marginTop })
  .width(StyleConstants.BLOCK_WIDTH_PERCENT)
  .padding({ top: $r('app.float.block_vertical_padding'), bottom: $r('app.float.block_vertical_padding') })
}

运行时，提示string与number类型不对