HarmonyOS ohos.data.preferences 数据存储,使用preferences 单例模式

export class GlobalContext { 
  private constructor() { 
  } 
 
  private static instance: GlobalContext; 
  private _objects = new Map<string, Object>(); 
 
  public static getContext(): GlobalContext { 
    if (!GlobalContext.instance) { 
      GlobalContext.instance = new GlobalContext(); 
    } 
    return GlobalContext.instance; 
  } 
 
  getObject(value: string): Object | undefined { 
    return this._objects.get(value); 
  } 
 
  setObject(key: string, objectClass: Object): void { 
    this._objects.set(key, objectClass); 
  } 
} 
 
EntryAbility： 
let productPreferences: Function = (() => { 
  let preferences: Promise<dataPreferences.Preferences> = dataPreferences.getPreferences(context, key); 
  return preferences; 
}); 
GlobalContext.getContext().setObject('getProductPreferences', preferences);