使用NPOI和委托做EXCEL导出

首先，在用NPOI导出时，学习了邀月这篇文章NPOI根据Excel模板生成原生的Excel文件实例，在这里先行谢过了。

本篇文章在邀月的基本上，做了一些小的改动，加上委托的机制。因为在做导出时，加载模板，下载为EXCEL的代码相同，但是在设置EXCEL模板中的值时有很大的不同。所以以了一些小的改动。

改动后的主要类文件如下：

ExcelHelper:

public class ExcelHelper
    {
        private string templatePath;
        private string newFileName;
        private string templdateName;

        private string sheetName;

        public string SheetName
        {
            get { return sheetName; }
            set { sheetName = value; }
        }

        public ExcelHelper(string templdateName, string newFileName)
        {
            this.sheetName = "sheet1";
            templatePath = HttpContext.Current.Server.MapPath("/") + "/Config/Template/";
            this.templdateName = string.Format("{0}{1}", templatePath, templdateName);
            this.newFileName = newFileName;
        }

        public void ExportDataToExcel(Action<HSSFSheet> actionMethod)
        {

            using (MemoryStream ms = SetDataToExcel(actionMethod))
            {
                byte[] data = ms.ToArray();

                #region response to the client
                HttpResponse response = System.Web.HttpContext.Current.Response;
                response.Clear();
                response.Charset = "UTF-8";
                response.ContentType = "application/vnd-excel";//"application/vnd.ms-excel";
                System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", string.Format("attachment; filename=" + newFileName));
                System.Web.HttpContext.Current.Response.BinaryWrite(data);
                #endregion
            }
        }

        private MemoryStream SetDataToExcel(Action<HSSFSheet> actionMethod)
        {
            //Load template file
            FileStream file = new FileStream(templdateName, FileMode.Open, FileAccess.Read);
            HSSFWorkbook workbook = new HSSFWorkbook(file);
            HSSFSheet sheet = workbook.GetSheet(SheetName);

            if (actionMethod != null) actionMethod(sheet);

            sheet.ForceFormulaRecalculation = true;
            using (MemoryStream ms = new MemoryStream())
            {
                workbook.Write(ms);
                ms.Flush();
                ms.Position = 0;
                sheet = null;
                workbook = null;

                return ms;
            }
        }
    }

PrintManager:

public class PrintManager
    {
        public void PrintPurchase()
        {
            ExcelHelper helper = new ExcelHelper("PurchaseOrder.xls", "PurchaseOrder_C000001.xls");

            helper.ExportDataToExcel(SetPurchaseOrder);
        }

        private void SetPurchaseOrder(HSSFSheet sheet)
        {
            HSSFRow row = null;
            HSSFCell cell = null;

            row = sheet.GetRow(2);
            cell = row.GetCell(1);
            cell.SetCellValue("C0000001");
            cell = row.GetCell(7);
            cell.SetCellValue("2013-04-18");


            DataTable itemDT = PrepareItemDTForTest();
            SetDataTableValue(sheet, 7, 0, itemDT);

            row = sheet.GetRow(14);
            cell = row.GetCell(0);
            cell.SetCellValue("NOKIA");
            cell = row.GetCell(6);
            cell.SetCellValue("CMCC");
        }

        public void SetDataTableValue(HSSFSheet sheet, int rowIndex, int columnIndex,DataTable dt) 
        {
            HSSFRow row = null;
            HSSFCell cell = null;
            foreach (DataRow dataRow in dt.Rows)
            {
                row = sheet.GetRow(rowIndex);
                columnIndex = 0;
                foreach (DataColumn column in dt.Columns)
                {
                    cell = row.GetCell(columnIndex);
                    string drValue = dataRow[column].ToString();
                    
                    switch (column.DataType.ToString())
                    {
                        case "System.String":
                            cell.SetCellValue(drValue);
                            break;
                        case "System.DateTime":
                            DateTime dateV;
                            DateTime.TryParse(drValue, out dateV);
                            cell.SetCellValue(dateV);

                            break;
                        case "System.Boolean":
                            bool boolV = false;
                            bool.TryParse(drValue, out boolV);
                            cell.SetCellValue(boolV);
                            break;
                        case "System.Int16":
                        case "System.Int32":
                        case "System.Int64":
                        case "System.Byte":
                            int intV = 0;
                            int.TryParse(drValue, out intV);
                            cell.SetCellValue(intV);
                            break;
                        case "System.Decimal":
                        case "System.Double":
                            double doubV = 0;
                            double.TryParse(drValue, out doubV);
                            cell.SetCellValue(doubV);
                            break;
                        case "System.DBNull":
                            cell.SetCellValue("");
                            break;
                        default:
                            cell.SetCellValue("");
                            break;
                    }
                    columnIndex++;
                }

                rowIndex++;
            }
        }
        
        private DataTable PrepareItemDTForTest() 
        {
            DataTable itemDT = new DataTable();
            itemDT.Columns.Add("Name");
            itemDT.Columns.Add("Qty", Type.GetType("System.Decimal"));
            itemDT.Columns.Add("UnitPrice", Type.GetType("System.Decimal"));
            DataRow newRow = itemDT.NewRow();
            newRow[0] = "820";
            newRow[1] = "100";
            newRow[2] = "3000";
            itemDT.Rows.Add(newRow);

            DataRow newRow2 = itemDT.NewRow();
            newRow2[0] = "920";
            newRow2[1] = "100";
            newRow2[2] = "4000";
            itemDT.Rows.Add(newRow2);
            return itemDT;
        }
    }

备注：

ExcelHelper类:负责打开模板，调用传来的方法设置值，输出流。

PrintManager类:负责调用ExcelHelper然后到业务模块取数据，然后将业务数据填充到HSSFSheet中去。

效果

EXCEL模板：

导出的EXCEL：

DEMO下载：NopiTest.zip