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