这段代码就是想取动态URL地址的图片的大小，请高手帮帮忙

在aspx页面添加一个按钮可直接运行  我想取http://www.gpssz.com/picture/2000147717/20070924155755.jpg图片的大小（字节）， 这段代码就是想取动态URL地址的图片的大小，请高手帮帮忙
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Data;using System.IO;
using System.Net;
public partial class zzzzz : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {    }    protected void Button1_Click1(object sender, EventArgs e)
    {
        try
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.gpssz.com/picture/2000147717/20070924155755.jpg");
            WebResponse response = request.GetResponse();
            Stream stream = response.GetResponseStream();
            byte[] buffer = new byte[1024];            if (!response.ContentType.ToLower().StartsWith("text/"))
            {
                try
                {
                    Stream outStream = new MemoryStream();
                    Stream inStream = response.GetResponseStream();                    int bufferLength;
                    do
                    {
                        bufferLength = inStream.Read(buffer, 0, buffer.Length);
                        if (bufferLength > 0)
                            outStream.Write(buffer, 0, bufferLength);
                    }
                    while (bufferLength > 0);                    outStream.Flush();
                    outStream.Seek(0, SeekOrigin.Begin);
                    inStream.Close();                    Image image = Image.FromStream(outStream);
                    Response.Write(image.GetPropertyItem(0).Len);
                    outStream.Close();
                    Response.Write("image :=" + image.Width + "X" + image.Height);
                    image.Dispose();
                }
                catch (Exception ex)
                {
                    Response.Write("非图像格式\r\n" + ex.Message);
                }
            }
            else
            {
                Response.Write("非图像格式");
            }
        }
        catch
        {
            Response.Write("找不到文件！");
        }
    }
}