应用开发时如何全局保存变量，在ets文件中使用

GlobalContext.getContext().setObject(‘applicationPathDir’, applicationPathDir);

let applicationPathDir: string = GlobalContext.getContext().getObject(‘applicationPathDir’) as string;

export class GlobalContext { 
  private constructor() { 
  } 
  private static instance: GlobalContext; 
  private _object = 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._object.get(value); 
  } 
  setObject(key: string, objectClass: Object): void { 
    this._object.set(key, objectClass) 
  } 
}