c# fileupload 如何设定文件类型

//取得文件的扩展名,并转换成小写

& & & & & & & & & & & string fileExtension = System.IO.Path.GetExtension(FileUpload1.FileName).ToLower()

& & & & & & & & & & & //限定只能上传jpg和gif图片

& & & & & & & & & & & string[] allowExtension = { ".jpg", ".gif", ".txt", ".xls" }