增加: 1.使用block; 2.支持中文编码;

具体使用:

(IBAction)askListBtnClick:(id)sender;
(IBAction)uploadFileBtnClick:(id)sender;
(IBAction)downloadBtnClick:(id)sender;
(IBAction)deleteFileBtnClick:(id)sender;
(IBAction)createDirBtnClick:(id)sender;
(IBAction)deleteDirBtnClick:(id)sender;