上传图片

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using DAL;

public partial class Manage_test : System.Web.UI.Page
{
    ProductDAO dbObj = new ProductDAO();
    string filePath;
    string filename;
    string fileEx;
    string serverpath;
    string relativepath;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            //this.labIamge.Visible = false;
            this.imgUrl.ImageUrl = "../Images/ftp/" + filename;
        }

    }
    protected void UploadImage_Click(object sender, EventArgs e)
    {
        try
        {
            if (imageUpload.PostedFile.FileName == "")
            {

                Page.ClientScript.RegisterStartupScript(Page.GetType(), "message", 

"<script language='javascript' defer>alert('要上传的文件不允许为空！')</script>");
                return;
            }
            else
            {
                filePath = imageUpload.PostedFile.FileName;
                filename = filePath.Substring(filePath.LastIndexOf("\\") + 1);
                fileEx = filePath.Substring(filePath.LastIndexOf(".") + 1);
                serverpath = Server.MapPath(@"~\Images\ftp\") + filename;
                relativepath = @"~\images\ftp\" + filename;
                this.imgUrl.ImageUrl = "../Images/ftp/" + filename;
                DataTable dsTable = dbObj.SelectProductByImg(filename);
                if (dsTable.Rows.Count > 0)
                {
                    Page.ClientScript.RegisterStartupScript(Page.GetType(), 

"message", "<script language='javascript' defer>alert('该图片已存在！')</script>");

                }
                else
                {
                    //判断图片格式
                    if (fileEx == "jpg" || fileEx == "bmp" || fileEx == "gif")
                    {
                        //生成缩略图
                        System.Drawing.Image image, newimage;
                        image = System.Drawing.Image.FromFile(filePath);
                        System.Drawing.Image.GetThumbnailImageAbort callb = null;
                        newimage = image.GetThumbnailImage(135, 100, callb, new 

System.IntPtr());
                        //把缩略图保存到指定的虚拟路径
                        newimage.Save(serverpath);
                        //释放image对象占用的资源
                        newimage.Dispose();
                        image.Dispose();
                        //imageUpload.PostedFile.SaveAs(serverpath);
                        //将图片的信息保存在数据库中
                        if (dbObj.InsertImg(filename))
                        {
                            Page.ClientScript.RegisterStartupScript(Page.GetType(), 

"message", "<script language='javascript' defer>alert('上传成功！')</script>");

                        }

                    }
                    else
                    {
                        Page.ClientScript.RegisterStartupScript(Page.GetType(), 

"message", "<script language='javascript' defer>alert('上传的图片扩展名错误！')

</script>");


                    }

                }

            }

        }
        catch (Exception error)
        {
            //labIamge.Text = "处理发生错误！原因：" + error.ToString();
        }
    }

    

    }