原文路徑: https://www.cnblogs.com/xionglee/articles/1353227.html
string fullPath = @"\WebSite1\Default.aspx";
string filename = System.IO.Path.GetFileName(fullPath);//文件名 “Default.aspx”
string extension = System.IO.Path.GetExtension(fullPath);//擴展名 “.aspx”
string fileNameWithoutExtension = System.IO.Path.GetFileNameWithoutExtension(fullPath);// 沒有擴展名的文件名 “Default”