WEB C#上传图片保存成缩略图

using System;
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 System.IO;
using System.Drawing;
using System.Drawing.Imaging;

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

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        HttpPostedFile hpf = File1.PostedFile;
        char[] splitChar = { '\\' };
        string[] FilenameArray = File1.Value.Split(splitChar);
        //Response.Write(File1.Value );
        //Response.Write("<script>alert(" +   + ")</script>");
        string Filename = FilenameArray[FilenameArray.Length - 1].ToLower();
        if (hpf.FileName.Length < 1)
        {
            Response.Write("<script>alert('请选择上传图片')</script>");
            return;
        }
        //if (hpf.ContentType != "image/pjpeg" && hpf.ContentType != "image/gif")
        //{
        //    Response.Write("<script>alert('图片格式不对')</script>");
        //}
        else
        {
            System.Text.StringBuilder sb = new System.Text.StringBuilder();
            sb.Append(DateTime.Now.Year.ToString());
            sb.Append(DateTime.Now.Month.ToString());
            sb.Append(DateTime.Now.Day.ToString());
            sb.Append(DateTime.Now.Hour.ToString());
            sb.Append(DateTime.Now.Minute.ToString());
            sb.Append(DateTime.Now.Second.ToString());
            if (File1.Value.ToLower().EndsWith("gif"))
            {
                sb.Append(".gif");
            }
            else if (File1.Value.ToLower().EndsWith("jpg"))
            {
                sb.Append(".jpg");
            }
            Filename=sb.ToString();

            string originalfilename = hpf.FileName;
            string strfile="D:/" + Filename;
            System.Drawing.Image image = System.Drawing.Image.FromStream(hpf.InputStream,true );
            System.Drawing.Size size = new Size(150, 150);
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(size.Width, size.Height);//新建bmp图片
            System.Drawing.Graphics graphics = System.Drawing.Graphics.FromImage(bitmap);//新建画板

            graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;//设置高质量插值法
            graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//设置高质量,低速度呈现平滑程度

            graphics.Clear(Color.White);//清空画布

            //在指定位置画图
            graphics.DrawImage(image , new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height), new System.Drawing.Rectangle(0,0,image.Width ,image.Height ),System.Drawing.GraphicsUnit.Pixel);

            //保存缩略图
            try
            {
                bitmap.Save(strfile, System.Drawing.Imaging.ImageFormat.Jpeg);
                Response.Write("<script>alert('保存成功')</script>");

            }
            catch (Exception ex)
            {
                Response.Write("保存缩略图失败" + ex.Message);
            }

            graphics.Dispose();
            image.Dispose();
            bitmap.Dispose();
        }
    }

}