通过浏览器下载服务端图片到客户端

<%@ Page Language="C#" %>  

<%
    //使用方法
    //DownloadFile.aspx?file=要下载的图片url  

    string url = HttpContext.Current.Request.Url.Query.ToLower();  

    //file=dddd.jpg
    url = url.Replace("?file=", "");  

    Response.BufferOutput = false;  

    Response.Clear();
    Response.ContentType = "application/x-msdownload";
    Response.AppendHeader("Content-Disposition", "attachment; filename=" + url);
    Response.ContentType = "application/octstream";
    Response.CacheControl = "Private";
    System.IO.Stream stm = new System.IO.FileStream(Server.MapPath(url), System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read);
    Response.AppendHeader("Content-length", stm.Length.ToString());  

    System.IO.BinaryReader br = new System.IO.BinaryReader(stm);  

    byte[] bytes;  

    for (Int64 x = 0; x < (br.BaseStream.Length / 4096 + 1); x++)
    {
        bytes = br.ReadBytes(4096);
        Response.BinaryWrite(bytes);
        System.Threading.Thread.Sleep(5);  //休息一下,防止耗用带宽太多。
    }  

    stm.Close();  

%> 

前端调用下载

$("#download").click(function() {
            window.location.href = "DownloadFile.aspx?file=" + "/kjzbsc/qrcode.jpg";
        });