public partial class WebForm : System.Web.UI.Page    {        protected void Page_Load(object sender, EventArgs e)        {            if (!IsPostBack)            {            }        }        protected void btnDownLoad_Click(object sender, EventArgs e)        {            try            {                if (!string.IsNullOrWhiteSpace(hidImageUrl.Value))                {                    Response.Buffer = true;                    Response.AddHeader("Accept-Language", "zh-tw");                    string content = hidImageUrl.Value;                    HttpWebRequest req = (HttpWebRequest)WebRequest.Create(content);                    req.Timeout = 10000;                    HttpWebResponse rep = (HttpWebResponse)req.GetResponse();                    Stream s = rep.GetResponseStream();                    hidImageUrl.Value = "";                    Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(DateTime.Now.ToString("yyyyMMddHHmmss") + ".jpeg", System.Text.Encoding.UTF8));//attachment                    Response.ContentType = "image/jpeg;charset=gbk";                    System.Drawing.Image img = System.Drawing.Image.FromStream(s);                    img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);                    s.Close();                    rep.Close();                    Response.End();                }            }            catch (Exception ex)            {                Response.Write("请联系管理员！" + ex.ToString());            }        }    }}

 下载

function downloadFile(fileName, content) {    $('#ContentPlaceHolder1_hidImageUrl').val(content);    $('#ContentPlaceHolder1_btnDownLoad').click();    return false;}

以上代码主要是通过JS代码调用服务器控件的OnClick事件；在后台把图片下载后保存至Response流中；实现类似下载Excel文件的功能