C#利用NPOI操作Excel文件

　　NPOI作为开源免费的组件，功能强大，可用来读写Excel(兼容xls和xlsx两种版本)、Word、PPT文件。可是要让我们记住所有的操作，这便有点困难了，至此，总结一些在开发中常用的针对Excel的简单。NPOI官网地址

　　本文地址：https://www.cnblogs.com/CKExp/p/9626022.html

一、NPOI的安装

　　下载NPOI或是通过Nuget包加入进来，然后在代码中引用如下命名空间，然后开始读写Excel文件。

using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using NPOI.HSSF.UserModel;
using NPOI.SS.Util;

二、NPOI写入Excel文件

　　在NPOI中，使用HSSFWorkbook类类来处理xls结尾的Excel文件(版本在2003及以前)，XSSFWorkbook类来处理xlsx结尾的Excel文件(版本在2007及以后)，都继承自接口IWorkbook，我们可以使用IWorkbook来统一处理两种不同格式的Excel文件。

　　直接参考相关代码即可，对于合并单元格的跨行跨列操作，无需将被跨掉的行生成新行，合并单元格的信息是单独保存的。设置单元格样式时，请创建一个新的样式对象，不创建将使用默认的样式对象。

/// <summary>
/// Datable导出到Excel
/// </summary>
/// <returns></returns>
public static void DataTableToExcel()
{    
    //一些已有数据信息
    bool fileSaved = false;
    SaveFileDialog saveDialog = new SaveFileDialog
    {
        DefaultExt = "xls",
        Filter = "Excel文件|*.xls",
        FileName = DateTime.Now.ToString("yyyyMMdd") + "-" + enterpriseTable.Rows[0]["名称"].ToString() + "委托书"
    };
    saveDialog.ShowDialog();
    string saveFileName = saveDialog.FileName;
    if (saveFileName.IndexOf(":") < 0) return; //被点了取消
    if (saveFileName != "")
    {
        try
        {
            IWorkbook workbook;
            string fileExt = System.IO.Path.GetExtension(saveFileName).ToLower();
            if (fileExt == ".xlsx")
            {
                workbook = new XSSFWorkbook();
            }
            else if (fileExt == ".xls")
            {
                workbook = new HSSFWorkbook();
            }
            else
            {
                return;
            }

            ISheet sheet = workbook.CreateSheet("Sheet1");

            sheet.AddMergedRegion(new CellRangeAddress(0, 3, 0, 9));//合并单元格
            IRow row = sheet.CreateRow(0);//创建首行
            ICell cell = row.CreateCell(0);//行中创建第一列
            cell.SetCellValue("标题");
            ICellStyle style = workbook.CreateCellStyle();//设置样式，创建新的style实例，脱离统一样式
            style.Alignment = NPOI.SS.UserModel.HorizontalAlignment.Center;//设置单元格的样式：水平对齐居中
            style.VerticalAlignment = NPOI.SS.UserModel.VerticalAlignment.Center;

            IFont font = workbook.CreateFont();//新建一个字体样式对象
            font.Boldweight = short.MaxValue; //设置字体加粗样式
            style.SetFont(font); //使用SetFont方法将字体样式添加到单元格样式中 
            cell.CellStyle = style; //将新的样式赋给单元格

            sheet.AddMergedRegion(new CellRangeAddress(4, 4, 1, 4));
            sheet.AddMergedRegion(new CellRangeAddress(4, 4, 6, 9));
            row = sheet.CreateRow(4);
            cell = row.CreateCell(0);
            cell.SetCellValue("编号:");
            cell = row.CreateCell(1);
            cell.SetCellValue(planCode);
            cell = row.CreateCell(5);
            cell.SetCellValue("日期：");
            cell = row.CreateCell(6);
            cell.SetCellValue(taskPlantable.Rows[0]["编制日期"].ToString());

            sheet.AddMergedRegion(new CellRangeAddress(5, 5, 1, 4));
            sheet.AddMergedRegion(new CellRangeAddress(5, 5, 6, 9));
            row = sheet.CreateRow(5);
            cell = row.CreateCell(0);
            cell.SetCellValue("单位:");
            cell = row.CreateCell(1);
            cell.SetCellValue(enterpriseTable.Rows[0]["名称"].ToString());
            cell = row.CreateCell(5);
            cell.SetCellValue("联系人：");
            cell = row.CreateCell(6);
            cell.SetCellValue(enterpriseTable.Rows[0]["联系人"].ToString());

            sheet.AddMergedRegion(new CellRangeAddress(6, 6, 1, 4));
            sheet.AddMergedRegion(new CellRangeAddress(6, 6, 6, 9));
            row = sheet.CreateRow(6);
            cell = row.CreateCell(0);
            cell.SetCellValue("传真:");
            cell = row.CreateCell(1);
            cell.SetCellValue(enterpriseTable.Rows[0]["传真"].ToString());
            cell = row.CreateCell(5);
            cell.SetCellValue("联系电话：");
            cell = row.CreateCell(6);
            cell.SetCellValue(enterpriseTable.Rows[0]["电话"].ToString());

            sheet.AddMergedRegion(new CellRangeAddress(7, 7, 1, 9));
            row = sheet.CreateRow(7);
            cell = row.CreateCell(0);
            cell.SetCellValue("详细地址:");
            cell = row.CreateCell(1);
            cell.SetCellValue(enterpriseTable.Rows[0]["详细地址"].ToString());

            int index = 7;
            //数据
            for (int i = 0; i < taskProjectTable.Rows.Count; i++)
            {
                index++;
                sheet.AddMergedRegion(new CellRangeAddress(index, index, 1, 4));
                sheet.AddMergedRegion(new CellRangeAddress(index, index, 6, 9));
                row = sheet.CreateRow(index);
                cell = row.CreateCell(0);
                cell.SetCellValue("名称:");
                cell = row.CreateCell(1);
                cell.SetCellValue(taskProjectTable.Rows[i]["名称"].ToString());
                cell = row.CreateCell(5);
                cell.SetCellValue("类型:");
                cell = row.CreateCell(6);
                cell.SetCellValue(taskProjectTable.Rows[i]["项目类型"].ToString());

                index++;
                sheet.AddMergedRegion(new CellRangeAddress(index, index, 0, 2));
                sheet.AddMergedRegion(new CellRangeAddress(index, index, 3, 5));
                sheet.AddMergedRegion(new CellRangeAddress(index, index, 6, 9));
                row = sheet.CreateRow(index);
                cell = row.CreateCell(0);
                cell.SetCellValue("项目");
                cell = row.CreateCell(3);
                cell.SetCellValue("方法");
                cell = row.CreateCell(6);
                cell.SetCellValue("仪器");
                
                //获取数据信息
                DataTable taskDataTable = mysql.GetTableFromSQL(selstr.ToString());
                selstr.Clear();
                for (int j = 0; j < taskDataTable.Rows.Count; j++)
                {
                    index++;
                    sheet.AddMergedRegion(new CellRangeAddress(index, index, 0, 2));
                    sheet.AddMergedRegion(new CellRangeAddress(index, index, 3, 5));
                    sheet.AddMergedRegion(new CellRangeAddress(index, index, 6, 9));
                    row = sheet.CreateRow(index);
                    cell = row.CreateCell(0);
                    cell.SetCellValue(taskDataTable.Rows[j]["名称"].ToString());
                    cell = row.CreateCell(3);
                    cell.SetCellValue(taskDataTable.Rows[j]["方法"].ToString());
                    cell = row.CreateCell(6);
                    cell.SetCellValue(taskDataTable.Rows[j]["仪器型号"].ToString());
                }
            }

            //转为字节数组  
            MemoryStream stream = new MemoryStream();
            workbook.Write(stream);
            var buf = stream.ToArray();

            //保存为Excel文件  
            using (FileStream fs = new FileStream(saveDialog.FileName, FileMode.Create, FileAccess.Write))
            {
                fs.Write(buf, 0, buf.Length);
                fs.Flush();
            }
            fileSaved = true;
        }
        catch (Exception ex)
        {
            fileSaved = false;
            MessageBox.Show("导出文件时出错,文件可能正被打开！
" + ex.Message);
        }
    }
    GC.Collect();//强行销毁

    if (fileSaved && File.Exists(saveFileName))
    {
        MessageBox.Show("导出成功！", "通知");
        Process.Start(saveFileName);
    }
    else
    {
        MessageBox.Show("导出失败！", "通知");
    }
}

 

三、NPOI读取Excel文件

　　打开指定Excel文件并读取文件中的内容，加入到DataTable中，或是加入到其它的数据载体中。

/// <summary>
/// Excel导入成DataTble
/// </summary>
/// <param name="file">导入路径(包含文件名与扩展名)</param>
/// <returns></returns>
public static DataTable ExcelToTable(string file)
{
    DataTable dt = new DataTable();
    IWorkbook workbook;
    string fileExt = Path.GetExtension(file).ToLower();
    using (FileStream fs = new FileStream(file, FileMode.Open, FileAccess.Read))
    {
        if (fileExt == ".xlsx") { workbook = new XSSFWorkbook(fs); } else if (fileExt == ".xls") { workbook = new HSSFWorkbook(fs); } else { workbook = null; }
        if (workbook == null) { return null; }
        ISheet sheet = workbook.GetSheetAt(0);

        //表头  
        IRow header = sheet.GetRow(sheet.FirstRowNum);
        List<int> columns = new List<int>();
        for (int i = 0; i < header.LastCellNum; i++)
        {
            object obj = GetValueType(header.GetCell(i));
            if (obj == null || obj.ToString() == string.Empty)
            {
                dt.Columns.Add(new DataColumn("Columns" + i.ToString()));
            }
            else
                dt.Columns.Add(new DataColumn(obj.ToString()));
            columns.Add(i);
        }
        //数据  
        for (int i = sheet.FirstRowNum + 1; i <= sheet.LastRowNum; i++)
        {
            DataRow dr = dt.NewRow();
            bool hasValue = false;
            foreach (int j in columns)
            {
                dr[j] = GetValueType(sheet.GetRow(i).GetCell(j));
                if (dr[j] != null && dr[j].ToString() != string.Empty)
                {
                    hasValue = true;
                }
            }
            if (hasValue)
            {
                dt.Rows.Add(dr);
            }
        }
    }
    return dt;
}

四、对单元格数据类型的操作

　　获取目标单元格的数据类型及数据值。

/// <summary>
/// 获取单元格类型
/// </summary>
/// <param name="cell">目标单元格</param>
/// <returns></returns>
private static object GetValueType(ICell cell)
{
    if (cell == null)
        return null;
    switch (cell.CellType)
    {
        case CellType.Blank: 
            return null;
        case CellType.Boolean:  
            return cell.BooleanCellValue;
        case CellType.Numeric:  
            return cell.NumericCellValue;
        case CellType.String:  
            return cell.StringCellValue;
        case CellType.Error:  
            return cell.ErrorCellValue;
        case CellType.Formula: 
        default:
            return "=" + cell.CellFormula;
    }
}

　　将数据设置到目标单元格中，并设置为指定数据格式。

/// <summary>
/// 设置单元格数据类型
/// </summary>
/// <param name="cell">目标单元格</param>
/// <param name="obj">数据值</param>
/// <returns></returns>
public static void SetCellValue(ICell cell, object obj)
{
    if (obj.GetType() == typeof(int))
    {
        cell.SetCellValue((int)obj);
    }
    else if (obj.GetType() == typeof(double))
    {
        cell.SetCellValue((double)obj);
    }
    else if (obj.GetType() == typeof(IRichTextString))
    {
        cell.SetCellValue((IRichTextString)obj);
    }
    else if (obj.GetType() == typeof(string))
    {
        cell.SetCellValue(obj.ToString());
    }
    else if (obj.GetType() == typeof(DateTime))
    {
        cell.SetCellValue((DateTime)obj);
    }
    else if (obj.GetType() == typeof(bool))
    {
        cell.SetCellValue((bool)obj);
    }
    else
    {
        cell.SetCellValue(obj.ToString());
    }
}

　　本文地址：https://www.cnblogs.com/CKExp/p/9626022.html

2018-09-11,望技术有成后能回来看见自己的脚步