FileUpload控件实现单按钮图片自动上传并带预览显示

1 <asp:FileUpload ID="fuPhoto" onchange="javascript:__doPostBack(‘lbtnUpload‘,‘‘)"  runat="server" ToolTip="选择图片" ForeColor="White" Width="68"/>
2 <asp:LinkButton ID="lbtnUpload" runat="server" OnClick="lbUploadPhoto_Click"></asp:LinkButton>
3 <img id="img" runat="server" src="" />

 1 /// <summary>
 2 /// 自动上传事件
 3 /// </summary>
 4 /// <param name="sender"></param>
 5 /// <param name="e"></param>
 6 protected void lbUploadPhoto_Click(object sender, EventArgs e)
 7 {
 8     fileUpload();
 9 }
10 //从控件上传文件
11 public void fileUpload()
12 {
13     if (fuPhoto.PostedFile != null && fuPhoto.PostedFile.ContentLength > 0)
14     {
15        //1. 验证文件格式
16         string ext = System.IO.Path.GetExtension(fuPhoto.PostedFile.FileName).ToLower();
17         if (ext != ".jpg" && ext != ".gif"&&ext!=".png")
18         {
19             Response.Write("文件非法！");
20             return;
21         }
22         string savePath = Server.MapPath("~/upload/");//指定上传文件在服务器上的保存路径
23         //2. 检查服务器上是否存在这个物理路径，如果不存在则创建
24         if (!System.IO.Directory.Exists(savePath))
25         {
26             System.IO.Directory.CreateDirectory(savePath);
27         }
28         Random random = new Random(DateTime.Now.Millisecond);
29         string fileName = DateTime.Now.ToString("yyMMddhhmmss") + random.Next(10000)+ext;
30         string path = savePath + fileName;
31         fuPhoto.PostedFile.SaveAs(path);
32         this.img1.Src = "upload/" + fileName;
33     }
34     else
35     {
36 //do some thing;
37     }
38 }