DataTable数据导出生成Excel文件

DataTable dt = wad.GetToExcel(lblcode.Text);
StringWriter sw = new StringWriter();

sw.WriteLine("代号,货品编码,货品名称,单位,净需求量,采购量,供应商,下单日期,到货日期,采购员,报关,状态,采购订单号");
foreach (DataRow item in dt.Rows)
{ 
 //string state = (OPSState)Convert.ToInt32(item["imgstate"]);
 sw.WriteLine(item["code"]   ","   item["goodscode"]   ","  
    item["goodsname"]   ","   item["unit"]   ","  
    item["netdemand"]   ","   item["shoppingnum"]   ","  
    item["tradername"]   ","   item["orderdate"]   ","  
    item["arrivaldate"]   ","   item["buyername"]   ","  
    item["ifcustoms"]   ","   (OPSState)Convert.ToInt32(item["imgstate"])   ","  
    item["ordercode"] );
}
Response.AddHeader("Content-Disposition", "attachment;   filename=test.csv");
Response.ContentType = "application/ms-excel";
Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
Response.Write(sw);
sw.Close();
Response.End();