%@ Page Language="C#" AutoEventWireup="true" CodeFile="up3.aspx.cs" Inherits="up3" %>
!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
html xmlns="http://www.w3.org/1999/xhtml">
head runat="server">
title>/title>
script language="javascript" type="text/javascript">
function addFile() {
var odiv = document.getElementById("MyFile");
var str = "div>input name='File' type='file' />/div>";
odiv.insertAdjacentHTML("beforeEnd", str);
}
function resetFile() {
var odiv = document.getElementById("MyFile");
odiv.innerHTML = "div>input name='File' type='file' />/div>";
}
/script>
/head>
body>
form id="form1" runat="server" enctype="multipart/form-data">
input type="button" value="增加" onclick="addFile()" />
input type="button" value="重置" onclick="resetFile()" />
div id="MyFile">
div>input name="File" type="file" />/div>
/div>
asp:Button runat="server" Text="上传" ID="Button1" OnClick="Button1_Click" BorderColor="Desktop"
BorderWidth="1px" Height="20px" Width="60px">/asp:Button>
div>
asp:Label ID="Label1" runat="server">/asp:Label>
/div>
/form>
/body>
/html>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
public partial class up3 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
string upPath = "/up/"; //上传文件路径
int upLength = 5; //上传文件大小
string upFileExtName = "|bmp|jpg|jpeg|png|gif|";
HttpFileCollection _files = System.Web.HttpContext.Current.Request.Files;
int flag = _files.Count;
int flagN = 0;
int flagE = 0;
int flagEE = 0;
string flagEEstr = "";
for (int i = 0; i _files.Count; i++)
{
string name = _files[i].FileName;
FileInfo fi = new FileInfo(name);
string oldfilename = fi.Name;
string scExtension = fi.Extension.ToLower();
string fileName = DateTime.Now.ToString("yyyyMMddhhmmssfff") + fi.Extension; // 文件名称，当前时间（yyyyMMddhhmmssfff）
string webFilePath = Server.MapPath(upPath) + fileName; // 服务器端文件路径
if (upFileExtName.IndexOf(scExtension.Replace(".", "")) == -1)
{
flagEE = flagEE + 1;
flagEEstr = flagEEstr + "第" + (i + 1) + "个文件，文件名[" + oldfilename + "]，文件类型不符合！";
continue;
}
if ((fi.Length / (1024 * 1024)) > upLength)
{
flagEE = flagEE + 1;
flagEEstr = flagEEstr + "第" + (i + 1) + "个文件，文件名[" + oldfilename + "]，超出" + upLength + "M大小限制！";
continue;
}
try
{
_files[i].SaveAs(webFilePath);
}
catch (Exception ex)
{
flagEE = flagEE + 1;
flagEEstr = flagEEstr + "第" + (i + 1) + "个文件，上传异常【"+ex.Message+"】";
}
}
Label1.Text = "总文件【" + flag + "】，上传成功文件【" + flagN + "】，异常文件【" + (flagE + flagEE) + "】【" + flagEEstr + "】";
}
}