在运行时绘制数据表后下载文件

Question

我从数据库返回数据表，并在运行时将其作为表格绘制，如下面的代码

string Link = dt_Materials.Rows[x]["Link"].ToString();
material_data += "<td><div style='font-family:Tahoma; font-size:15px; text-align:center;'>" + ClassPeriod + "</div></td>";
material_data += "<td><a onclick='mona(" + Link + ");'><img style='margin-top:5px;'         width='20' height='20' src='../Contents/images/trash.png' title='delete album'/></a></td>";

当用户点击图片时，应该根据该功能的链接下载文件

public void mona(string strRequest)
{ 
    try
    {
        // string strRequest = Request.QueryString["file"]; //-- if something was passed to the file querystring
        if (strRequest != "")
        {
            string path = Server.MapPath("materialFolder"+ strRequest); //get file object as FileInfo  
            System.IO.FileInfo file = new System.IO.FileInfo(path); //-- if the file exists on the server  


            if (file.Exists) //set appropriate headers  
            {
                Response.Clear();
                Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);
                Response.AddHeader("Content-Length", file.Length.ToString());
                Response.ContentType = "application/octet-stream";



                Response.WriteFile(file.FullName);


                Response.End();
            }
            else
            {

                Response.Write("This file does not exist.");
            }
        }
        else
        {
            //nothing in the URL as HTTP GET
            Response.Write("Please provide a file to download.");
        }



    }
    catch (Exception ex)
    {

    }
}

我想知道为什么当我点击时，没有发生任何事件