Question

我的问题是我在数据库中有很多信息，理想情况下我想把它从一个excel文件中提取出来供客户下载。

我正在使用非常棒的NPOI库，并且已经在系统中的控制台应用程序中实现，但这不是我写的。

当前发生了什么，当我点击我的控制器的ActionLink时，显示空白页面只显示“System.IO.MemoryStream”..

显然这不是预期的效果。我希望它的方式是当用户点击链接时，报告会下载。

以下是报告的类：

    public class RepairReporting
    {
        public Stream GenerateRepairFile(List<Int64> itemIds)
        {
            // Getting the complete workbook...
            //
            MemoryStream ms = new MemoryStream();
            HSSFWorkbook templateWorkbook = new HSSFWorkbook();

            // Create a worksheet by it's name.
            //
            HSSFSheet sheet = templateWorkbook.CreateSheet("Repairs Report");
            sheet.ForceFormulaRecalculation = true;



            HSSFRow dataRow = sheet.CreateRow(0);

            HSSFCell cell = dataRow.CreateCell(0);
            cell.SetCellValue("Repairs");


            cell = dataRow.CreateCell(1);
            cell.SetCellValue(DateTime.Now);

            // Build the header row
            //
            dataRow = sheet.CreateRow(1);

            string[] colHeaders = new string[]{ "Product Code",
                                                "Product Name",
                                                "Customer", 
                                                "Date Submitted For Repair",
                                                "Date Sent For Repair", 
                                                "Expected Release Date",    
                                                "Estimated Cost",   
                                                "Actual Cost",  
                                                "Total Repair Price (END PRICE)"
                                                };

            int colPosition = 0;

            // Write all the headers out.
            //
            foreach (string colHeader in colHeaders)
            {
                cell = dataRow.CreateCell(colPosition++);
                cell.SetCellValue(colHeader);
            }

            // Build the item rows.
            //
            int row = 2;

            foreach (Int64 itemId in itemIds)
            {
                using (ModelContainer ctn = new ModelContainer())
                {

                    Item currentItem = (from t in ctn.Items
                                          where t.ItemID == itemId && t.RepairSelection == true
                                          select t).First();


                    dataRow = sheet.CreateRow(row++);
                    colPosition = 0;

                    cell = dataRow.CreateCell(colPosition++);
                    cell.SetCellValue(currentItem.ProductCode);

                    cell = dataRow.CreateCell(colPosition++);
                    cell.SetCellValue(currentItem.Product);

                    cell = dataRow.CreateCell(colPosition++);
                    cell.SetCellValue(currentItem.Customer.Name);


                    cell.SetCellValue(currentItem.Repair.SubmissionDate.Value.ToString("MM/dd/yyyy"));


                    if (currentItem.Repair.SentForConversion != null)
                    {
                        cell = dataRow.CreateCell(colPosition++);
                        cell.SetCellValue(currentItem.Repair.SentForRepair.Value.ToString("MM/dd/yyyy"));
                    }
                    else
                    {
                        colPosition++;
                        colPosition++;
                    }

                    if (currentItem.Repair.ReleaseDate != null)
                    {
                        cell = dataRow.CreateCell(colPosition++);
                        cell.SetCellValue(currentItem.Repair.ReleaseDate.Value.ToString("MM/dd/yyyy"));
                    }
                    else
                    {
                        colPosition++;
                        colPosition++;
                    }


                    if (currentItem.Repair.CostEstimation != null)
                    {
                        cell = dataRow.CreateCell(colPosition++);
                        cell.SetCellValue(currentItem.Repair.CostEstimation.Value.ToString());
                    }
                    else
                    {
                        colPosition++;
                        colPosition++;
                    }

                    if (currentItem.Repair.ActualCost != null)
                    {
                        cell = dataRow.CreateCell(colPosition++);
                        cell.SetCellValue(currentItem.Repair.ActualCost.Value.ToString());
                    }
                    else
                    {
                        colPosition++;
                        colPosition++;
                    }

                    if (currentTitle.Repair.TotalRepairPrice != null)
                    {
                        cell = dataRow.CreateCell(colPosition++);
                        cell.SetCellValue(currentItem.Repair.TotalRepairPrice.Value.ToString());
                    }
                    else
                    {
                        colPosition++;
                        colPosition++;
                    }

                }

            }


            templateWorkbook.Write(ms);
            ms.Position = 0;

            return ms;
        }
    }
}

然后这是我的控制器，我认为这就是我的问题所在：

    public Stream repairReport()
    {
        ModelContainer ctn = new ModelContainer();

        List<Title> items = null;

        var itemObjects = ctn.Items.Where(t => t.RepairSelection == true)
            .Select(t =>t);

        items = itemObjects.ToList();

        RepairReporting rtp = new RepairReporting();


        List<long> itemIDs = items.Select(t => t.ItemID).ToList();

        Stream repairReport = rtp.GenerateRepairFile(itemIDs);

        return repairReport;
    }

Answer 1

如果这是您在Controller中的操作方法，则可以返回FileResult返回FileStreamResult，其stream在其构造函数中带有ContentType

public FileResult RepairReport()
{
    ModelContainer ctn = new ModelContainer();

    List<Title> items = ctn.Items.Where(t => t.RepairSelection == true)
        .Select(t =>t).ToList();

    RepairReporting rtp = new RepairReporting();

    List<long> itemIDs = items.Select(t => t.ItemID).ToList();

    Stream repairReport = rtp.GenerateRepairFile(itemIDs);

    return new FileStreamResult(repairReport, "application/ms-excel")
        {
            FileDownloadName = "RepairReport.xls",
        };
}

Answer 2

2个问题

太多行可能会导致内存问题。
当您声明新变量时，例如dataRow.CreateCell。因为你调用COM互操作，试着处理你使用的每个对象。 obj.Dispose（）;和Marshal.Release（obj）;我不认为NPOI会管理它。

下载excel文件

2 个答案: