导出文件标题

Question

以下代码是导出内容没有导出文本标题
请教高手..
void ExportData(object sender)//导出文本
        {
            lock (this)
            {
                Type typeentity = sender.GetType();
                if (isTxt)
                {
                    StreamWriter sw = new StreamWriter(ExportFilePath, true);
                    string strLine = null;                    foreach (PropertyInfo pro in typeentity.GetProperties())
                    {
                        strLine += "    " + pro.GetValue(sender, null).ToString();
                    }
                    sw.WriteLine(strLine);
                    strLine = "";
                    sw.WriteLine("");
                    sw.Close();
                    GC.Collect();
                }
                else
                {
                    ExportExcel(sender);
                }
            }
           
        }