前台代码：
代码
1 <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="imgupload._Default" %>
2
3 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
4
5 <html xmlns="http://www.w3.org/1999/xhtml" >
6 <head runat="server">
7 <title></title>
8 </head>
9 <body>
10 <form id="form1" runat="server">
11 <div>
12
13 <asp:FileUpload ID="FileUpload1" runat="server" />
14 <asp:Button ID="Button1" runat="server" Text="上传" onclick="Button1_Click" />
15 <br />
16 <asp:Image ID="img" runat="server" />
17
18 </div>
19 </form>
20 </body>
21 </html>
22
2
3 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
4
5 <html xmlns="http://www.w3.org/1999/xhtml" >
6 <head runat="server">
7 <title></title>
8 </head>
9 <body>
10 <form id="form1" runat="server">
11 <div>
12
13 <asp:FileUpload ID="FileUpload1" runat="server" />
14 <asp:Button ID="Button1" runat="server" Text="上传" onclick="Button1_Click" />
15 <br />
16 <asp:Image ID="img" runat="server" />
17
18 </div>
19 </form>
20 </body>
21 </html>
22
后台代码：
code
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Web;
5 using System.Web.UI;
6 using System.Web.UI.WebControls;
7
8 namespace imgupload
9 {
10 public partial class _Default : System.Web.UI.Page
11 {
12 protected void Page_Load(object sender, EventArgs e)
13 {
14 this.img.Visible = false;
15 }
16 protected void Button1_Click(object sender, EventArgs e)
17 {
18 string fullfilename = this.FileUpload1.PostedFile.FileName;
19 string filename = fullfilename.Substring(fullfilename.LastIndexOf("\\")+1);
20 string typefilename = fullfilename.Substring(fullfilename.LastIndexOf(".")+1);
21 if (typefilename == "jpg" || typefilename == "gif" || typefilename == "png")
22 {
23 this.FileUpload1.SaveAs(Server.MapPath("upload") + "\\" + filename);
24 this.img.ImageUrl = "upload/" + filename;
25 this.img.Visible = true;
26 Response.Write("上传成功");
27 }
28 else
29 {
30 Response.Write("<script>alert('错误的图片文件格式');history.back();");
31 }
32 }
33 }
34 }
35
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Web;
5 using System.Web.UI;
6 using System.Web.UI.WebControls;
7
8 namespace imgupload
9 {
10 public partial class _Default : System.Web.UI.Page
11 {
12 protected void Page_Load(object sender, EventArgs e)
13 {
14 this.img.Visible = false;
15 }
16 protected void Button1_Click(object sender, EventArgs e)
17 {
18 string fullfilename = this.FileUpload1.PostedFile.FileName;
19 string filename = fullfilename.Substring(fullfilename.LastIndexOf("\\")+1);
20 string typefilename = fullfilename.Substring(fullfilename.LastIndexOf(".")+1);
21 if (typefilename == "jpg" || typefilename == "gif" || typefilename == "png")
22 {
23 this.FileUpload1.SaveAs(Server.MapPath("upload") + "\\" + filename);
24 this.img.ImageUrl = "upload/" + filename;
25 this.img.Visible = true;
26 Response.Write("上传成功");
27 }
28 else
29 {
30 Response.Write("<script>alert('错误的图片文件格式');history.back();");
31 }
32 }
33 }
34 }
35