//前台代码
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="test.aspx.cs" Inherits="test" %>

   

//后台代码

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;

public partial class test : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string UploadFileName, UploadFileLastName;
        UploadFileName = FileUpload1.PostedFile.FileName;//文件在本地的原始位置   
        UploadFileLastName = UploadFileName.Substring(UploadFileName.LastIndexOf(".") + 1);//得到文件的扩展名
        Random rd = new Random();//产生随机数
        int valationNo = 10 + rd.Next(99);//产生随机数
        string suiji = valationNo.ToString();//产生随机数
        string UpLoadFileTime = DateTime.Now.ToString("yyyyMMddHHmmss") + suiji;//得到系统时间并加上随机数以便生成上传图片名称
        string NewUploadFileName = UpLoadFileTime + "." + UploadFileLastName;//产生上传图片的名称

        string UserDirectory = "TestFile";//所要创建文件夹的名字，实际运用中可为用户注册ID
        string UserPath = Server.MapPath("UploadFiles").ToString() + "\" + UserDirectory + "\" + "ProductsImages";
        if (!Directory.Exists(UserPath)) //如果文件夹不存在则创建
        {
            Directory.CreateDirectory(UserPath);
        }
        FileUpload1.PostedFile.SaveAs(NewUploadPahtName);//用保存的方法将图片上载
        string sUser_ProductsImageUrl = "UploadFiles/" + UserDirectory + "/" + "ProductsImages/" + NewUploadFileName;//得到服务端图片的虚拟路径
        //Response.Write(sUser_ProductsImageUrl);
    }
}