<a href="文件的具体地址">点击下载</a>

------解决方案--------------------
只能打包下载，B/S好多人都在问能不能批量下载；至今都没好的解决方案。

------解决方案--------------------

C# code
 nP += "<a href=指定下载页面.aspx?path="+finfo[i].FullName+">"+finfo[i].Name+"</a>"+"<br>";


然后在下载页面的 pageload中写代码如下

        string filePath =Request["path"];//通过URL传过来的参数
        FileInfo fileInfo = new FileInfo(filePath);
        Response.Clear();
        Response.ClearContent();
        Response.ClearHeaders();
        Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
        Response.AddHeader("Content-Length", fileInfo.Length.ToString());
        Response.AddHeader("Content-Transfer-Encoding", "binary");
        Response.ContentType = "application/octet-stream";
        Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
        Response.WriteFile(fileInfo.FullName);
        Response.Flush();
        Response.End();