引用自：
asp.net获取网站路径
http://hi.baidu.com/zhangfengbang/blog/item/5f99d74b0ce661f883025cbc.html
HttpRequest 成员
http://msdn.microsoft.com/zh-cn/library/system.web.httprequest_members(v=VS.80).aspx
ASP.NET获取网站根目录的url的函数，很简单
http://www.xueit.com/html/2009-03/21_932_00.html
 

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网站在服务器磁盘上的物理路径: HttpRuntime.AppDomainAppPath
虚拟程序路径: HttpRuntime.AppDomainAppVirtualPath

任何于Request/HttpContext.Current等相关的方法, 都只能在有请求上下文或者页面时使用. 即在无请求上下文时,HttpContext.Current为null. 而上面提到的方法一直可用.

对于全局Cache对象的访问亦然.

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示例：输出asp.net 网站路径。 

 

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在ASP.NET编程中经常需要用Request获取url的有关信息.

测试的url地址是http://www.test.com/testweb/default.aspx, 结果如下：
Request.ApplicationPath:                     /testweb
Request.CurrentExecutionFilePath:       /testweb/default.aspx
Request.FilePath:                                /testweb/default.aspx
Request.Path:                                     /testweb/default.aspx
Request.PathInfo:
Request.PhysicalApplicationPath:          E:\WWW\testweb\
Request.PhysicalPath:                         E:\WWW\testweb\default.aspx
Request.RawUrl:                                 /testweb/default.aspx
Request.Url.AbsolutePath:                    /testweb/default.aspx
Request.Url.AbsoluteUri:                      http://www.test.com/testweb/default.aspx
Request.Url.Host:                                www.test.com
Request.Url.LocalPath:                        /testweb/default.aspx 

当url中带参数时可以使用:
HttpContext.Current.Request.Url.PathAndQuery.ToString()//

本页地址:   Request.URL; 

上页地址:  
Request.UrlReferrer  
Request.ServerViables["http_referer"]  
Request.RawUrl  
Request.RawUrl.QueryAndPath  
System.IO.Path.GetFileName(Request.FilePath.ToString()) 

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获取网站根目录的url源代码--2010.05.09
http://www.xueit.com/html/2009-03/21_932_00.html

public static string GetRootURI()
    {
        string AppPath = "";
        HttpContext HttpCurrent = HttpContext.Current;
        HttpRequest Req;
        if (HttpCurrent != null)
        {
            Req = HttpCurrent.Request;
            string UrlAuthority = Req.Url.GetLeftPart(UriPartial.Authority);
            if (Req.ApplicationPath == null || Req.ApplicationPath == "/")
                //直接安装在   Web   站点   
                AppPath = UrlAuthority;
            else
                //安装在虚拟子目录下   
                AppPath = UrlAuthority + Req.ApplicationPath;
        }
        return AppPath;
    }

可修改为静态属性 

private static string rootURI;

    /// <summary>
    /// 获得网站根目录的url的函数
    /// </summary>
    /// <returns>应用程序根目录 eg:  http://www.xxx.net:2156/im </returns>
    public static string RootURI
    {
        get
        {
            if (string.IsNullOrEmpty(rootURI))
            {
                HttpContext HttpCurrent = HttpContext.Current;
                HttpRequest Req;
                if (HttpCurrent != null)
                {
                    Req = HttpCurrent.Request;

                    string UrlAuthority = Req.Url.GetLeftPart(UriPartial.Authority);
                    if (Req.ApplicationPath == null || Req.ApplicationPath == "/")
                        //直接安装在   Web   站点   
                        rootURI = UrlAuthority;
                    else
                        //安装在虚拟子目录下   
                        rootURI = UrlAuthority + Req.ApplicationPath;
                }
            }

            return rootURI;
        }
    }