使用NPOI读取Excel到DataTable

怼烎@ 2022-07-17 00:21 222阅读 0赞

一、NPOI介绍：

使用 NPOI 你就可以在没有安装 Office 或者相应环境的机器上对 WORD/EXCEL 文档进行读写。NPOI是构建在POI 3.x版本之上的，它可以在没有安装Office的情况下对Word/Excel文档进行读写操作

二、安装NPOI

新建控制台应用程序>管理NuGet程序包>搜索NPOI>安装NPOI

![20160823171708160][]

三.下面是我需要的读取的Excel文件，数据格式如下：

![20160823171840287][]

四.添加ExcelHelper类：

using System;
    using NPOI.SS.UserModel;
    using NPOI.XSSF.UserModel;
    using NPOI.HSSF.UserModel;
    using System.IO;
    using System.Data;
    
    namespace NPOI.ReadExcel
    {
        public class ExcelHelper : IDisposable
        {
            private string fileName = null; //文件名
            private IWorkbook workbook = null;
            private FileStream fs = null;
            private bool disposed;
    
            public ExcelHelper(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)
                        {
                            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;
                }
            }
    
            /// <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;
                }
            }
        }
    }

五，读取文件到DataTable:

using System;
    using System.Collections.Generic;
    using System.Data;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    
    namespace NPOI.ReadExcel
    {
        class Program
        {
            static void Main(string[] args)
            {
                ExcelHelper excel_helper = new ExcelHelper(AppDomain.CurrentDomain.BaseDirectory + "test.xlsx");
                DataTable dt = excel_helper.ExcelToDataTable("",true);
    
                List<string> tableList=GetColumnsByDataTable(dt);
                for (int i = 0; i < tableList.Count; i++)
                {
                    foreach (DataRow item in dt.Rows)
                    {
                        try
                        {
                            if (item[0].ToString() != "")
                            {
                                if (i < tableList.Count - 1 & item[i + 1].ToString()!="")
                                {
                                    Console.WriteLine(item[0].ToString()+"\t"+item[i+1].ToString());
                                }
                            }
                        }
                        catch (Exception ex)
                        { }
                    }
                    Console.WriteLine("");
                }
    
                Console.ReadKey();
            }
    
            /// <summary>
            /// 根据datatable获得列名
            /// </summary>
            /// <param name="dt">表对象</param>
            /// <returns>返回结果的数据列数组</returns>
            public static List<string> GetColumnsByDataTable(DataTable dt)
            {
                List<string> strColumns =new List<string> ();
    
                if (dt.Columns.Count > 0)
                {
                    int columnNum = 0;
                    columnNum = dt.Columns.Count;;
                    for (int i = 0; i < dt.Columns.Count; i++)
                    {
                        strColumns.Add(dt.Columns[i].ColumnName);
                    }
                }
                return strColumns;
            } 
        }
    }

![20160823172332918][]

[20160823171708160]: /images/20220717/ebf878efdc1045a493bba9497f2bfa81.png
[20160823171840287]: /images/20220717/c107824f8ca84e428cf7c8d3f7fa3b87.png
[20160823172332918]: /images/20220717/199e749fae8644d78ecb528b8a669307.png