public override void Visit(PublicService service)
 {
     Console.WriteLine("可疑人员访问公有服务,拒绝访问");
 }
 public override void Visit(PublicService service)
 {
     Console.WriteLine("管理员访问公有服务,允许所有操作");
 }
 public override void Visit(PublicService service)
 {
     Console.WriteLine("普通人员访问公有服务,拥有读取权限");
 }
 public abstract void Visit(PublicService service);