C#网站开发----在服务器上生成临时文件,下载到客户端,然后删除临时文件

//点击按钮,完成在服务器上生成文件,并下载到客户端的任务.

  protected void btnOutput_Click(object sender, EventArgs e)
    {
        try
        {
            fillGridView_emp(this.grd_employee, this.grd_emp_temp);

            string strYear = this.lstYear.Text;
            string strSeason = this.lstPeriod.Text;

            foreach (GridViewRow grdRow in this.grd_employee.Rows)
            {

                //本想做成一次下载多个选中的对象,但是后来却发现做不了,于是就改成了CheckBox只能选中一个.这样就不会出问题了.    

                if(((CheckBox)(grdRow.Cells[4]).FindControl("ckb_Output")).Checked == true)
                {
                    string strLocalEmpNo = ((LinkButton)(grdRow.Cells[1].Controls[0])).Text.ToString();
                    string strLocalEmpName =  (grdRow.Cells[2]).Text.ToString();

                    //write to excel
                    if (false == writeToExcel(strYear, strSeason, strLocalEmpNo, strLocalEmpName))
                    {
                        //error message
                    }
                    else
                    {
                        //System.GC.Collect();放在这个地方,服务器上的EXCEL进程杀不了,

                   //若放在下面(蓝色部分)则可以,具体原因不明,有待研究.
                        string strFileName = Session["fullName"].ToString();
                        FileDownload(strFileName);
                    }
                    break;
                }
            }

        }
        catch (System.Exception ex)
        {
            ExceptionHandler.HandleException(ex);
        }
        finally
        {
            System.GC.Collect();
        }

    }



    /// <summary>
    /// 在服务器上生成一个包含所需内容的临时文件
    /// </summar