using System.IO;  //引入命名空间     

         string path = "text.aspx";

         string pathName = Path.GetFileName(path);       //获取文件全名 text.aspx

         string pathName1 = Paht.GetFileNameWithoutExtension(path);    //获取文件名 text

         string pathName2 = Path.GetExtension(path);    //获取文件后缀名 aspx

    

FileInfo 类

         FileInfo fi = new FileInfo("C:/abc.txt");

         fi.Extension 值：.txt