文件上传实例（文件上传，自动重命名，自动添加文件夹）

本文介绍了一个使用ASP.NET实现的文件上传功能，支持图片预览，并根据文件类型将文件保存到不同的目录下。代码中详细展示了如何获取文件信息、判断文件类型、生成唯一文件名以及保存文件。

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前台代码：ASPX

@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="Album_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

</head>

<body>

<div>

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

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

<asp:Image ID="Image1" runat="server" Height="100px" /><br />

<asp:Label ID="Label1" runat="server"></asp:Label></div>

</form>

</body>

</html>

后台代码：CS

using System;

using System.Data;

using System.Configuration;

using System.Collections;

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;

public partial class Album_Default : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

Image1.Visible = false;

}

protected void Button1_Click(object sender, EventArgs e)

{

string filename = FileUpload1.FileName;

string size = FileUpload1.PostedFile.ContentLength.ToString();

string[] myfile = filename.Split('.');

string dotname = myfile[myfile.Length - 1].ToString().ToLower();

string type = FileUpload1.PostedFile.ContentType;

string type2 = filename.Substring(filename.LastIndexOf(".") + 1);

string imgpath = Server.MapPath("~/Upimg") + "//";

string filepath = Server.MapPath("~/Upfile") + "//";

string folder = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString();

if (type2 == "jpg" || type2 == "gif")

{

Image1.Visible = true;

if (!System.IO.Directory.Exists(imgpath + folder))

{//自动生成文件夹

System.IO.Directory.CreateDirectory(imgpath + folder);

}

Random myrdn = new Random();//产生随机数

//日期，时间，随机数和后缀名

string newfilename = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() + myrdn.Next(10000).ToString() + "." + dotname;

FileUpload1.SaveAs(imgpath + folder + "//" + newfilename);