C# NPOI批量導出數據到Excel，並自適應寬度，而且適用於服務器

首先需要引用NPOI的dll文件。

下載地址：https://me.csdn.net/download/laizhixue

HTML代碼：

<a id='ExportMyExcel_a' class='k-button' href='' style='display:none;'>圖標1</a>
<br/>
<a class='k-button' title='導出相應的Excel' onclick='ExportMyExcel()'>圖標2</a>

前臺方法： 

    //laizhixue 2019.06.18
    //導出自定義數據的Excel數據	
    function ExportMyExcel() {
        $.ajax({
            url: "/Report/CommonReport/ExportMyExcel",
            data: {
                ProcSetName: $("#sltProcess").data("kendoDropDownList").text(),
                StartDate:$("#ProcStartDate").val(),
                EndDate: $("#ProcEndDate").val()
            },
            dataType: "text",
            async: false,
            success: function (data) {
                if (data.indexOf("導出成功！\n若已打開文件，數據則不會覆蓋之前已存在的文件！") >= 0) {
                    var url = data.substring(data.indexOf(":") + 1);
                    $("#ExportMyExcel_a").attr("href", url);
                    document.getElementById("ExportMyExcel_a").click();//需JS觸發click,JQ觸發失敗
                    DeleteFile( $("#ExportMyExcel_a").attr("href"));
                } else {
                    alert(data);
                }
            }
        });
    }

    //刪除文件
    function DeleteFile(url) {
        $.ajax({
            url: "/Report/CommonReport/DeleteFile",
            data: {
                Url:url
            },
            dataType: "text",
            async: false,
            success: function (data) {
                if (data == "error") {
                    alert(data);
                }
            }
        });

    }

 後臺方法：

        //laizhixue 2019-06-18
        //導出自定義數據的Excel數據			
        public string ExportMyExcel(string ProcSetName, string StartDate, string EndDate)
        {
            string conStr = System.Web.Configuration.WebConfigurationManager.ConnectionStrings["aZaaSFramework"].ToString();
            var list = new List<List<string>>();
            //調用存儲過程拉取相應的數據
            try
            {
                //NPOI
                string bookpath = Server.MapPath("~\\Content\\");
                string bookName = ProcSetName + '-' + StartDate + '-' + EndDate + ".xls";
                string filepath = bookpath  + bookName;
                string str = "";
                
                //SQL
                DataSet ds = new DataSet();
                SqlConnection con = new SqlConnection(conStr);
                con.Open();
                SqlCommand command = new SqlCommand("ExportMyExcel", con);
                command.CommandType = CommandType.StoredProcedure;//採用存儲過程
                command.Parameters.Add("@ProcSetName", SqlDbType.NVarChar, 100);//流程名字
                command.Parameters["@ProcSetName"].Value = ProcSetName;
                command.Parameters.Add("@StartDate", SqlDbType.NVarChar, 100);//開始日期
                command.Parameters["@StartDate"].Value = StartDate + " 00:00:00";
                command.Parameters.Add("@EndDate", SqlDbType.NVarChar, 100);//結束日期
                command.Parameters["@EndDate"].Value = EndDate + " 23:59:59";
                command.Parameters.Add("@Status", SqlDbType.TinyInt);//狀態
                command.Parameters["@Status"].Value = 3;//完成
                SqlDataAdapter adapter = new SqlDataAdapter(command);
                adapter.Fill(ds);
                //獲取數據條數
                if (ds != null && ds.Tables.Count > 0)
                {
                    //創建workbook
                    HSSFWorkbook book = new HSSFWorkbook();

                    //創建Sheet1
                    ISheet sheet = book.CreateSheet("Sheet1");

                    //表頭
                    IRow headrow = sheet.CreateRow(0);

                    //添加表頭數據
                    for (var i = 0; i < ds.Tables[0].Columns.Count; i++)
                    {
                        ICell headcell = headrow.CreateCell(i);
                        headcell.SetCellValue(ds.Tables[0].Columns[i].ToString());
                        sheet.AutoSizeColumn(i);
                    }

                    //添加主數據  i行j列
                    for (var i = 0; i < ds.Tables[0].Rows.Count; i++)
                    {
                        //數據
                        IRow row = sheet.CreateRow(i + 1);
                        for (var j = 0; j < ds.Tables[0].Columns.Count; j++)
                        {
                            ICell cell = row.CreateCell(j);
                            //狀態轉中文
                            if (j == 0)
                            {
                                switch (ds.Tables[0].Rows[i][j].ToString())
                                {
                                    case "3":
                                        cell.SetCellValue("完成");
                                        break;
                                }
                            }
                            else
                            {
                                cell.SetCellValue(ds.Tables[0].Rows[i][j].ToString());
                            }
                        }
                    }
                    //獲取當前列的寬度，然後對比本列的長度，取最大值
                    //自適應寬度
                    for (int columnNum = 0; columnNum < ds.Tables[0].Columns.Count; columnNum++)
                    {
                        int columnWidth = sheet.GetColumnWidth(columnNum) / 256;
                        for (int rowNum = 0; rowNum < sheet.LastRowNum; rowNum++)
                        {
                            IRow currentRow;
                            //當前行未被使用過
                            if (sheet.GetRow(rowNum) == null)
                            {
                                currentRow = sheet.CreateRow(rowNum);
                            }
                            else
                            {
                                currentRow = sheet.GetRow(rowNum);
                            }

                            if (currentRow.GetCell(columnNum) != null)
                            {
                                ICell currentCell = currentRow.GetCell(columnNum);
                                int length = Encoding.Default.GetBytes(currentCell.ToString()).Length;
                                if (columnWidth < length)
                                {
                                    columnWidth = length;
                                }
                            }
                        }
                        sheet.SetColumnWidth(columnNum, columnWidth * 256);
                    }
                    // 寫入到服務器，需要下載到本地需要通過前臺的超鏈接
                    using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
                    {
                        book.Write(ms);
                      
                        using (FileStream fs = new FileStream(filepath, FileMode.Create, FileAccess.ReadWrite))
                        {
                            byte[] d = ms.ToArray();
                            fs.Write(d, 0, d.Length);
                            fs.Flush();
                        }
                        book = null;
                        ds.Dispose();
                    }
                    str = "導出成功！\n若已打開文件，數據則不會覆蓋之前已存在的文件！路徑:/Content/" + bookName;
                    return str;
                }
                else
                {
                    return "請檢查ExportMyExcel存儲過程是否已完善代碼！";
                }
            }
            catch
            {
                return "調用ExportMyExcel存儲過程異常！";
            }
        }

        //刪除服務器生成的文件
        public string DeleteFile(string Url)
        {
            try
            {
                FileInfo resFile = new FileInfo(Server.MapPath("~\\" + Url));//服務器的資源文件
                if (resFile.Exists)
                {
                    resFile.Delete();
                }
            }
            catch (Exception e)
            {
                System.Diagnostics.Debug.WriteLine("刪除文件異常！");
                return "error";
            }
            return "success";
        }

SQL存儲過程：

USE [aZaaS.Framework]
GO
/****** Object:  StoredProcedure [dbo].[ExportMyExcel]    Script Date: 07/02/2019 09:06:39 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
--獲取需要導出的相應流程的表格數據
ALTER procedure [dbo].[ExportMyExcel]
@ProcSetName nvarchar(100),--流程名
@StartDate nvarchar(100),--開始日期
@EndDate nvarchar(100),--結束日期
@Status nvarchar(100)--狀態
AS
DECLARE @sql NVARCHAR(max)
BEGIN
    IF @ProcSetName=N'供應商主檔流程'
    BEGIN
			--自定義導出字段
			SELECT 
			[Before_SupplierNo] as N'供應商編號'
			,[NewOrOldSel] as N'SAP系統'
			,[Before_SupplierName] as N'供應商名稱'
			,[Before_VendorClass1] as N'類別代碼1'
			,[Before_VendorClass2] as N'類別代碼2'
			,[Before_SearchCondition] as N'搜索條件'
			,[Before_Country] as N'國家'
			,[Before_Address_1] as N'街道1'
			,[Before_Address_2] as N'街道2'
			,[Before_Address_3] as N'街道3'
			,[Before_PhoneNo_1] as N'電話'
			,[Before_FaxNo] as N'傳真'
			,[Before_E_email] as N'電子信箱'
			,[Before_HeadOffice] as N'總部'
			,[Before_Currency] as N'訂單貨幣'
			,[Before_PaymentRule] as N'前付款條件'
			,[Before_Trade1] as N'國貿條件1'
			,[Before_Trade2] as N'國貿條件2'
			,[Before_Seller] as N'銷售員'
			,[Before_SellTel] as N'銷售電話'
			,[Before_Remarks] as N'備注'
			FROM 表名
END