C#导入导出EXCEL实例包括2003和2007以上版本

2019-01-14 修复 Excel空行出错
2018-10-27 修复 解决Excel超出DataTable列问题
2018-09-04 修复 导入时间格式问题

导入时间格式问题分析
之前整理的NPOI导入导出Excel 在之前使用过程中没发现问题。
但是后来发现导入的文档如果有日期时间格式,导入时会有混乱
后来找了一下解决方案,最终将其中一段修改即可导入日期(导出未测试)
原因

NPOI导入时会大概判断一下Excel文档里面的单元格是什么格式的内容,
有Blank,Boolean,Numeric,String,Error,Formula 等几种,
但是就是没有日期的,日期的单元格会被判断成Numeric(数字)类型,
所以日期格式的单元格就按数字类型来取其中的值,
所以单元格被判断成数字的之后还要再判断一下是否为日期格式。


如果C#基础不是很好的话,直接把我这个类拿过去用就可以了

C#导入导出EXCEL实例包括2003和2007以上版本
这个引用了NPOI,DLL文件   NPOI  DLL下面实例有下载
源码实例下载地址https://pan.baidu.com/s/1pLIEDwn


以下是核心源码
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System;
using System.Collections.Generic;
using System.Data;
using System.IO;

namespace PEC.Common
{
    /// <summary>
    /// 操作Excel通用类
    /// </summary>
    public class ExcelHelper
    {
        /// <summary>
        /// 从Excel读取数据
        /// 只支持单表
        /// </summary>
        /// <param name="FilePath">文件路径</param>
        public static DataTable ReadFromExcel(string FilePath)
        {
            DataTable result = null;
            IWorkbook wk = null;
            string extension = System.IO.Path.GetExtension(FilePath); //获取扩展名
            try
            {
                using (FileStream fs = File.OpenRead(FilePath))
                {
                    if (extension.Equals(".xls")) //2003
                    {
                        wk = new HSSFWorkbook(fs);
                    }
                    else                         //2007以上
                    {
                        wk = new XSSFWorkbook(fs);
                    }
                }

                //读取当前表数据
                ISheet sheet = wk.GetSheetAt(0);
       
                //构建DataTable
                IRow row = sheet.GetRow(0);
                result = BuildDataTable(row);
                if (result != null)
                {
                    if (sheet.LastRowNum >= 1)
                    {
                        for (int i = 1; i < sheet.LastRowNum + 1; i++)
                        {
                            IRow temp_row = sheet.GetRow(i);
                            if (temp_row == null) { continue; }//2019-01-14 修复 行为空时会出错
                            List<object> itemArray = new List<object>();
                            for (int j = 0; j < result.Columns.Count; j++)//解决Excel超出DataTable列问题    lqwvje20181027
                            {
                                //itemArray.Add(temp_row.GetCell(j) == null ? string.Empty : temp_row.GetCell(j).ToString());
                                itemArray.Add(GetValueType(temp_row.GetCell(j)));//解决 导入Excel  时间格式问题  lqwvje 20180904
                            }

                            result.Rows.Add(itemArray.ToArray());
                        }
                    }
                }
                return result;

            }
            catch (Exception ex)
            {
                return null;
            }
        }

        /// <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 static int DataTableToExcel(DataTable data, string sheetName, string fileName, bool isColumnWritten)
        {
            int i = 0;
            int j = 0;
            int count = 0;
            ISheet sheet = null;
            IWorkbook workbook = null;

            using (FileStream 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)
                        {
                            row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
                        }
                        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)
                        {
                            row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                        }
                        ++count;
                    }
                    workbook.Write(fs); //写入到excel

                    return count;
                }
                catch (Exception ex)
                {
                    Console.WriteLine("Exception: " + ex.Message);
                    return -1;
                }
            }
        }

        private static DataTable BuildDataTable(IRow Row)
        {
            DataTable result = null;
            if (Row.Cells.Count > 0)
            {
                result = new DataTable();
                for (int i = 0; i < Row.LastCellNum; i++)
                {
                    result.Columns.Add(Row.GetCell(i).ToString());
                }
            }
            return result;
        }

        /// <summary>
        /// 获取单元格类型
        /// </summary>
        /// <param name="cell"></param>
        /// <returns></returns>
        private static object GetValueType(ICell cell)
        {
            if (cell == null)
                return null;
            switch (cell.CellType)
            {
                case CellType.Blank: //BLANK:  
                    return null;
                case CellType.Boolean: //BOOLEAN:  
                    return cell.BooleanCellValue;
                case CellType.Numeric: //NUMERIC:  
                    short format = cell.CellStyle.DataFormat;
                    if (format != 0) { return Convert.ToDateTime(cell.DateCellValue).ToString("yyyy-MM-dd HH:mm:ss"); } else { return cell.NumericCellValue; }
                case CellType.String: //STRING:  
                    return cell.StringCellValue;
                case CellType.Error: //ERROR:  
                    return cell.ErrorCellValue;
                case CellType.Formula: //FORMULA:  
                default:
                    return "=" + cell.CellFormula;
            }
        }
    }
}


以下是调用上面导入导出的方法

        private void button2_Click(object sender, EventArgs e)
        {
            string strSql = "select * from H3AV61MeterMainData";//导出到Excel的DataTable
            DataSet ds = SQLiteHellper.ExecuteQuery(strSql);
            if (ds != null && ds.Tables.Count > 0 && ds.Tables[0].Rows.Count > 0)
            {
                FolderBrowserDialog folder = new FolderBrowserDialog();
                if (folder.ShowDialog() == DialogResult.OK)
                {
                    string ExportDir = folder.SelectedPath + "\\数据导出" + DateTime.Now.ToString("yyyyMMddHHmmss") + ".xlsx";
                    int i = DataTableToExcel(ds.Tables[0], "测试", ExportDir, true);
                    MessageBox.Show(i.ToString());
                }
            }
        }

        private void button3_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFile = new OpenFileDialog();
            if (openFile.ShowDialog() == DialogResult.OK)
            {
                string filePath = openFile.FileName;
                DataTable excelDt = ReadFromExcel(filePath);
                //把Excel读取到DataTable里面 然后再把DataTable存入数据库
            }
        }


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