<div>
<asp:FileUpload ID="FileUpload1" runat="server" />

<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="上传" />
</div>

protected void Button1_Click(object sender, EventArgs e)

    {

        if (this.FileUpload1.HasFile)

        {

            string fileName = Path.GetExtension(this.FileUpload1.FileName);

            string path = Server.MapPath("upload/");

            //在上传的同时重命名

            this.FileUpload1.SaveAs(path+Guid.NewGuid()+fileName);

            Response.Write("上传成功!");

        }

        else

        {

            Response.Write("请选择文件");

        }

    }