MemoryStream、StreamWriter下载

MemoryStream、StreamWriter

public ActionResult ExportCSV()
        {
            try
            {
                string Transactions = Request.Form["item"];

                List<long> arr = new List<long>();

                string[] strtemp = Transactions.Split(',');
                foreach (string strs in strtemp)
                {
                    arr.Add(long.Parse(strs));
                }
                List<PaymentMaster> PaymentList = Cerebus.GetTransactionDetails(Convert.ToInt64(this.CurrentAccount.csFacilityID), arr.ToArray());

                MemoryStream stream = new MemoryStream();
                StreamWriter writer = new StreamWriter(stream);

                writer.WriteLine("AccountName,Date,TransactionID,ItemDesc,Amount,TransactionTotal");
                writer.Flush();
                for (int i = 0; i < PaymentList.Count; i++)
                {
                    string Summary = string.Empty;
                    string PaymentIDF = string.Empty;
                    string PaymentID = string.Empty;
                    if (PaymentList[i].PaymentItems.Count > 0)
                        Summary = DelQuota(PaymentList[i].PaymentItems[0].Summary);

                    if (PaymentList[i].PaymentID > 0)
                        PaymentIDF = PaymentList[i].PaymentID.ToString();

                    writer.WriteLine(string.Format("{0},{1},{2},{3},{4},{5}",
                       PaymentList[i].AccountName,
                       Convert.ToDateTime(PaymentList[i].CreateDate,Constant.GetMDDYYFormat()).ToShortDateString(),
                       PaymentList[i].PaymentID,
                       Summary,
                       "$" + PaymentList[i].PaymentItems[0].Amount.ToString(),
                       ""
                      ));

                    if (PaymentList[i].PaymentItems.Count > 0)
                    {
                        for (int j = 0; j < PaymentList[i].PaymentItems.Count; j++)
                        {

                            if (PaymentList[i].PaymentItems[j].PaymentID > 0)
                                PaymentID = PaymentList[i].PaymentItems[j].PaymentID.ToString();
                            if (j != 0)
                            {
                                writer.WriteLine(string.Format("{0},{1},{2},{3},{4},{5}",
                                                              "",
                                                              "",
                                                              PaymentID,
                                                              DelQuota(PaymentList[i].PaymentItems[j].Summary),
                                                              "$" + PaymentList[i].PaymentItems[j].Amount.ToString(),
                                                              ""
                                                          ));
                            }
                        }
                        writer.WriteLine(string.Format("{0},{1},{2},{3},{4},{5}",
                               "",
                               "",
                               "",
                               "",
                               "",
                               "$" + PaymentList[i].Amount.ToString()
                        ));
                    }
                    writer.Flush();
                }

                stream.Position = 0;
                byte[] buffer = new byte[stream.Length];
                stream.Read(buffer, 0, buffer.Length);
                stream.Close();

                return File(buffer, "text/plain", "PaymentInvoice.csv");
            }
            catch (Exception)
            {
                return View();
            }
        }