跟导师请教后写出的关于C#导出Excel，不导出隐藏列的方法

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首先，建立一个GridView，放入DataTable
如图：

打开栏目设计器的话，是对数据进行操作：

我对aa bb两行数据，进行了隐藏操作：

这样可以看到，aa bb在GridView中是隐藏了的，但是如果没有对新数据进行操作的话，导出的Excel是包含了aa bb两列的，所以，对新数据进行保存操作，很重要，代码抛出：

 1 private DataTable GetGridViewDT(GridView view)
 2         {
 3             if (view.RowCount == 0)
 4                 return null;
 5             DataTable dt = new DataTable();
 6             var cols = view.Columns.Where(p => p.Visible).OrderBy(p => p.VisibleIndex);
 7             for (int i = 0; i < view.RowCount; i++)
 8             {
 9                 List<object> values = new List<object>();
10                 foreach (var col in cols)
11                 {
12                     object value = view.GetRowCellValue(i, col);
13                     if (i == 0)//添加列名
14                     {
15                         dt.Columns.Add(col.FieldName, col.ColumnType);
16                     }
17                     values.Add(value);
18                 }
19                 dt.Rows.Add(values.ToArray());
20             }
21             return dt;
22         }

顺便给出ExcelHelper类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using NPOI.HSSF.UserModel;
using System.IO;
using System.Data;
using System.ComponentModel;
using System.Windows.Forms;
using DevExpress.XtraGrid.Views.Grid;

namespace RpnTest.Excel
{
    public class ExcelHelperTrue : IDisposable
    {
        private string fileName = null; //文件名
        private IWorkbook workbook = null;
        private FileStream fs = null;
        private bool disposed;

        public ExcelHelperTrue(string fileName)
        {
            this.fileName = fileName;
            disposed = false;
        }



        /// <summary>
        /// 将DataTable数据导入到excel中
        /// </summary>
        /// <param name="data">要导入的数据</param>
        /// <param name="isColumnWritten">DataTable的列名是否要导入</param>
        /// <param name="sheetName">要导入的excel的sheet的名称</param>
        /// <returns>导入数据行数(包含列名那一行)</returns>
        public int DataTableToExcel(DataTable data, string sheetName, bool isColumnWritten)
        {
            int i = 0;
            int j = 0;
            int count = 0;
            ISheet sheet = null;

            fs = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite);
            if (fileName.IndexOf(".xlsx") > 0) // 2007版本
                workbook = new XSSFWorkbook();
            else if (fileName.IndexOf(".xls") > 0) // 2003版本
                workbook = new HSSFWorkbook();

            try
            {
                if (workbook != null)
                {
                    sheet = workbook.CreateSheet(sheetName);
                }
                else
                {
                    return -1;
                }
                if (isColumnWritten == true) //写入DataTable的列名
                {
                    IRow row = sheet.CreateRow(0);
                    for (j = 0; j < data.Columns.Count; ++j)//遍历循环数据行
                    {
                        row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);//写入数据
                    }
                    count = 1;
                }
                else
                {
                    count = 0;
                }

                for (i = 0; i < data.Rows.Count; ++i)
                {
                    IRow row = sheet.CreateRow(count);
                    for (j = 0; j < data.Columns.Count; ++j)
                    {
                        CellType _datatype = GetExcelType(data.Columns[j].DataType.ToString());
                        row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                        switch (_datatype)
                        {
                            case CellType.Numeric:
                                row.CreateCell(j).SetCellValue(Convert.ToDouble(data.Rows[i][j]));
                                break;
                            case CellType.String:
                                row.CreateCell(j).SetCellValue(Convert.ToString(data.Rows[i][j]));
                                break;
                            case CellType.Formula:
                                //IDataFormat datastyle = workbook.CreateDataFormat();
                                var cell = row.CreateCell(j);
                                cell.SetCellValue(Convert.ToDateTime(data.Rows[i][j]).ToString("yyyy-MM-dd"));
                                //cell.CellStyle.DataFormat = datastyle.GetFormat("yyyy-MM-dd");
                                break;
                            default:
                                row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                                break;
                        }
                        //cell.SetCellType(_datatype);
                        //if (_datatype == CellType.Formula)
                        //    cell.SetCellFormula("yyyy-MM-dd");
                    }
                    ++count;
                }
                workbook.Write(fs); //写入到excel
                return count;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.Message);
                return -1;
            }
        }
        /// <summary>
        /// Numeric = 0,
        //String = 1,
        //Formula = 2,
        //Blank = 3,
        //Boolean = 4,
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        /// 
        private CellType GetExcelType(string type)
        {
            CellType result = CellType.String;
            switch (type)
            {
                case "System.Int32":
                case "System.Decimal":
                case "System.Double":
                    result = CellType.Numeric;
                    break;
                case "System.DateTime":
                    result = CellType.Formula;
                    break;
            }
            return result;
        }
        /// <summary>
        /// 将excel中的数据导入到DataTable中
        /// </summary>
        /// <param name="sheetName">excel工作薄sheet的名称</param>
        /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param>
        /// <returns>返回的DataTable</returns>
        public DataTable ExcelToDataTable(string sheetName, bool isFirstRowColumn)
        {
            ISheet sheet = null;
            DataTable data = new DataTable();
            int startRow = 0;
            try
            {
                fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
                if (fileName.IndexOf(".xlsx") > 0) // 2007版本
                    workbook = new XSSFWorkbook(fs);
                else if (fileName.IndexOf(".xls") > 0) // 2003版本
                    workbook = new HSSFWorkbook(fs);

                if (sheetName != null)
                {
                    sheet = workbook.GetSheet(sheetName);
                    if (sheet == null) //如果没有找到指定的sheetName对应的sheet，则尝试获取第一个sheet
                    {
                        sheet = workbook.GetSheetAt(0);
                    }
                }
                else
                {
                    sheet = workbook.GetSheetAt(0);
                }
                if (sheet != null)
                {
                    IRow firstRow = sheet.GetRow(0);
                    int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数

                    if (isFirstRowColumn)
                    {
                        for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                        {
                            ICell cell = firstRow.GetCell(i);
                            if (cell != null)
                            {
                                string cellValue = cell.StringCellValue;
                                if (cellValue != null)
                                {
                                    DataColumn column = new DataColumn(cellValue);
                                    data.Columns.Add(column);
                                }
                            }
                        }
                        startRow = sheet.FirstRowNum + 1;
                    }
                    else
                    {
                        startRow = sheet.FirstRowNum;
                    }

                    //最后一列的标号
                    int rowCount = sheet.LastRowNum;
                    for (int i = startRow; i <= rowCount; ++i)
                    {
                        IRow row = sheet.GetRow(i);
                        if (row == null) continue; //没有数据的行默认是null　　　　　　　

                        DataRow dataRow = data.NewRow();
                        for (int j = row.FirstCellNum; j < cellCount; ++j)
                        {
                            if (row.GetCell(j) != null) //同理，没有数据的单元格都默认是null
                                dataRow[j] = row.GetCell(j).ToString();
                        }
                        data.Rows.Add(dataRow);
                    }
                }

                return data;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.Message);
                return null;
            }
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (!this.disposed)
            {
                if (disposing)
                {
                    if (fs != null)
                        fs.Close();
                }

                fs = null;
                disposed = true;
            }
        }
    }
}

最后，在窗体的button的单击事件代码中调用即可：

 private void toExcel1_Click(object sender, EventArgs e)
        {
            DataTable dt = GetGridViewDT(gridView1);
            SaveFileDialog dlg = new SaveFileDialog() { Filter = "Excel文件|*.xlsx" };
            if (dlg.ShowDialog() == DialogResult.OK)
            {
                //string filename = DateTime.Now.ToString("yyyymmddhhmmss");
                string filename = dlg.FileName;
                using (ExcelHelperTrue helper = new ExcelHelperTrue(filename))
                {
                    helper.DataTableToExcel(dt, "sheet", true);
                }
                Process.Start(filename);
            }
        }