C# 发送HttpWebRequest获得网络图片的大小、尺寸

/// <summary>
/// 获取图片的大小和尺寸
/// </summary>
/// <param name="aPhotoUrl">图片url</param>
/// <param name="aSize">图片大小</param>
/// <param name="aLength">图片尺寸</param>
private void GetPhotoInfo(string aPhotoUrl, ref string aSize, ref string aLength)
{
try
{
Uri mUri = new Uri(aPhotoUrl);
HttpWebRequest mRequest = (HttpWebRequest)WebRequest.Create(mUri);
mRequest.Method = "GET";
mRequest.Timeout = 200;
mRequest.ContentType = "text/html;charset=utf-8";
HttpWebResponse mResponse = (HttpWebResponse)mRequest.GetResponse();
Stream mStream = mResponse.GetResponseStream();
aSize = (mResponse.ContentLength / 1024).ToString() + "KB";
Image mImage = Image.FromStream(mStream);
aLength = mImage.Width.ToString() + "x" + mImage.Height.ToString();
mStream.Close();
}
catch (Exception e)
{
//MessageBox.Show(aPhotoUrl + "获取失败");
}
}