问题描述：
在一些类库中需要读取当前系统的xml文件，当时用HttpContext.Current无法找到实例化对象
解决代码如下：
XmlDocument xml = new XmlDocument();
???????????//加载xml文件
???????????try
???????????{
???????????????if (HttpContext.Current != null)
???????????????{
???????????????????xml.Load(HttpContext.Current.Server.MapPath("~/Configs/CityAreas.xml"));
???????????????}
???????????????else
???????????????{ ???????????????????????????????
???????????????????xml.Load(System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Configs\\CityAreas.xml"));
???????????????}
????????????
???????????}
???????????catch (Exception ex)
???????????{
???????????????Helper.ComHelper.CityDataLog("CityAreas配置有误，请及时检查！");
???????????}
HttpContext.Current.Server未将对象引用到实例
原文地址：https://www.cnblogs.com/pangzili/p/8870516.html