C# 使用NPOI操作Excel的工具类-编程知识

写在前面

NPOI是POI项目的.NET迁移版本。POI是一个开源的Java 读写 Excel、Word 等微软Ole2组件文档的项目；使用NPOI可以在没有安装Office或者相应环境的机器上对Word或Excel文档进行读写操作。

NPOI类库中操作EXCEL有两个模块分别是：

1️.HSSF模块，操作拓展名为.xls的Excel，对应Excel2003及以前的版本。
2️.XSSF模块，操作拓展名为.xlsx的Excel，对应Excel2007及以后的版本，可向下兼容xls，故本例使用XSSF下的XSSFWorkbook来操作。

通过NuGet获取NPOI

需要引用的命名空间如下：

using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System.Collections;
using System.Data;

代码实现

   public class ExcelProcessor{#region 私有变量private int _perSheetCount = 40000;//每个sheet要保存的条数private string _filePath;private IWorkbook _currentWorkbook;private List<string> _sheets;private Dictionary<string, DataTable> _dataDict;#endregion#region 属性public List<string> Sheets{get { return _sheets ?? (_sheets = GetSheets(_filePath)); }}#endregion#region 构造器/// <summary>/// 默认构造器/// </summary>/// <param name="filePath"></param>public ExcelProcessor(string filePath){_filePath = filePath;_dataDict = new Dictionary<string, DataTable>();}/// <summary>/// 加载数据/// </summary>public bool LoadData(){try{using (var fs = new FileStream(_filePath, FileMode.OpenOrCreate, FileAccess.Read)){_currentWorkbook = new XSSFWorkbook(fs);}return true;}catch (Exception ex){return false;}}/// <summary>/// 最大接收5万条每页，大于5万时，使用系统默认的值(4万)/// </summary>/// <param name="perSheetCounts"></param>public ExcelProcessor(int perSheetCounts){if (_perSheetCount <= 50000)_perSheetCount = perSheetCounts;}#endregion#region 公有方法public List<string> GetSheets(string fileName){var sheets = new List<string>();if (_currentWorkbook == null)return sheets;for (int i = 0; i < _currentWorkbook.NumberOfSheets; i++){sheets.Add(_currentWorkbook.GetSheetName(i));}return sheets;}public object GetNumericCellValue(string sheetName, int rowIndex, int colIndex){if (!Sheets.Contains(sheetName))return null;var cell = _currentWorkbook.GetSheet(sheetName).GetRow(rowIndex).GetCell(colIndex - 1);return cell.NumericCellValue;}public object GetStringCellValue(string sheetName, int rowIndex, int colIndex){if (!Sheets.Contains(sheetName))return null;var cell = _currentWorkbook.GetSheet(sheetName).GetRow(rowIndex).GetCell(colIndex - 1);if (cell == null)return null;if (cell.CellType == CellType.Formula){if (cell.CachedFormulaResultType == CellType.String)return cell.StringCellValue;if (cell.CachedFormulaResultType == CellType.Numeric)return cell.NumericCellValue;if (cell.CachedFormulaResultType == CellType.Boolean)return cell.BooleanCellValue;return null;}if (cell.CellType == CellType.Numeric)return cell.NumericCellValue;if (cell.CellType == CellType.Boolean)return cell.NumericCellValue;return cell.StringCellValue;}public object GetDateTimeCellValue(string sheetName, int rowIndex, int colIndex){if (!Sheets.Contains(sheetName))return null;var cell = _currentWorkbook.GetSheet(sheetName).GetRow(rowIndex).GetCell(colIndex - 1);if (cell.CellType == CellType.String)return cell.StringCellValue;return cell.DateCellValue;}public ICell GetCell(string sheetName, int rowIndex, int colIndex){if (!Sheets.Contains(sheetName))return null;var sheet = _currentWorkbook.GetSheet(sheetName);if (sheet == null)return null;var row = sheet.GetRow(rowIndex);if (row == null)return null;var cell = row.GetCell(colIndex - 1);if (cell == null)return null;return cell;}/// <summary>/// 获取单元格里面的值/// </summary>/// <param name="sheetName">表名</param>/// <param name="x">行索引从1开始</param>/// <param name="y">列索引从1开始</param>/// <returns></returns>public object GetCellValue(string sheetName, int rowIndex, int colIndex){if (!Sheets.Contains(sheetName))return null;DataTable dt = null;if (!_dataDict.ContainsKey(sheetName)){dt = Import(sheetName);_dataDict.Add(sheetName, dt);}else{dt = _dataDict[sheetName];}if (dt == null)return null;if (dt.Rows.Count < rowIndex)return null;var rowIdx = rowIndex - 1;var row = dt.Rows[rowIdx];var colIdx = colIndex - 1;return row[colIdx];}public void SetCellValues(ICell cell, string cellType, string cellValue){switch (cellType){case "System.String": //字符串类型double result;if (double.TryParse(cellValue, out result))cell.SetCellValue(result);elsecell.SetCellValue(cellValue);break;case "System.DateTime": //日期类型DateTime dateV;DateTime.TryParse(cellValue, out dateV);cell.SetCellValue(dateV);break;case "System.Boolean": //布尔型bool boolV = false;bool.TryParse(cellValue, out boolV);cell.SetCellValue(boolV);break;case "System.Int16": //整型case "System.Int32":case "System.Int64":case "System.Byte":int intV = 0;int.TryParse(cellValue, out intV);cell.SetCellValue(intV);break;case "System.Decimal": //浮点型case "System.Double":double doubV = 0;double.TryParse(cellValue, out doubV);cell.SetCellValue(doubV);break;case "System.DBNull": //空值处理cell.SetCellValue("");break;default:cell.SetCellValue("");break;}}public DataTable Import(string sheetName){sheetName = string.IsNullOrEmpty(sheetName) ? "Sheet1" : sheetName;ISheet sheet = _currentWorkbook.GetSheet(sheetName);if (sheet == null){sheet = _currentWorkbook.GetSheetAt(0);}IEnumerator ie = sheet.GetRowEnumerator();IRow row = null;var maxCol = 0;while (ie.MoveNext()){row = ie.Current as IRow;//取一行,为了得到column的总数if (row.LastCellNum > maxCol)maxCol = row.LastCellNum;}var dt = new DataTable();for (int i = 0; i < maxCol; i++){dt.Columns.Add(string.Format("Col{0}", i));}ie.Reset();DataRow drow = null;ICell cell = null;var isHeader = true;while (ie.MoveNext()){if (isHeader){isHeader = false;continue;}row = ie.Current as IRow;drow = dt.NewRow();for (int i = 0; i < row.LastCellNum; i++){if (row.GetCell(i) == null){drow[i] = null;continue;}cell = row.GetCell(i) as ICell;switch (cell.CellType){case CellType.Blank:drow[i] = string.Empty;break;case CellType.Boolean:drow[i] = cell.BooleanCellValue;break;case CellType.Error:drow[i] = cell.ErrorCellValue;break;case CellType.Formula:drow[i] = "=" + cell.CellFormula;break;case CellType.Numeric:if (DateUtil.IsCellDateFormatted(cell)){drow[i] = cell.DateCellValue;}else{drow[i] = cell.NumericCellValue;}break;case CellType.String:drow[i] = cell.StringCellValue;break;case CellType.Unknown:break;default:drow[i] = null;break;}}dt.Rows.Add(drow);}return dt;}public string Export(string excelFileName, List<DataTable> dataTables){var workbook = new HSSFWorkbook();ISheet sheet = null;IRow row = null;ICell cell = null;var index = 0;foreach (var dataTable in dataTables){var tableName = dataTable.TableName;if (string.IsNullOrEmpty(tableName))tableName = "Sheet" + (++index);sheet = workbook.CreateSheet(tableName);//填充表头row = sheet.CreateRow(0);for (int i = 0; i < dataTable.Columns.Count; i++){cell = row.CreateCell(i);cell.SetCellValue(dataTable.Columns[i].ColumnName);}//填充内容for (int i = 0; i < dataTable.Rows.Count; i++){row = sheet.CreateRow(i + 1);for (int j = 0; j < dataTable.Columns.Count; j++){cell = row.CreateCell(j);SetCellValues(cell, dataTable.Columns[j].DataType.ToString(), dataTable.Rows[i][j].ToString());}}}if (File.Exists(excelFileName)) File.Delete(excelFileName);using (var fs = new FileStream(excelFileName, FileMode.CreateNew, FileAccess.Write)) workbook.Write(fs);return excelFileName;}public string Export(string excelFileName, DataTable dataTable){HSSFWorkbook workbook = new HSSFWorkbook();ISheet sheet = null;IRow row = null;ICell cell = null;int sheetCount = 1;//当前的sheet数量int currentSheetCount = 0;//循环时当前保存的条数，每页都会清零//表头样式ICellStyle style = workbook.CreateCellStyle();style.Alignment = NPOI.SS.UserModel.HorizontalAlignment.Center;//内容样式style = workbook.CreateCellStyle();style.Alignment = NPOI.SS.UserModel.HorizontalAlignment.Center;sheet = workbook.CreateSheet("Sheet" + sheetCount);//填充表头row = sheet.CreateRow(0);for (int i = 0; i < dataTable.Columns.Count; i++){cell = row.CreateCell(i);cell.SetCellValue(dataTable.Columns[i].ColumnName);cell.CellStyle = style;}//填充内容for (int i = 0; i < dataTable.Rows.Count; i++){if (currentSheetCount >= _perSheetCount){sheetCount++;currentSheetCount = 0;sheet = workbook.CreateSheet("Sheet" + sheetCount);}if (sheetCount == 1)//因为第一页有表头，所以从第二页开始写row = sheet.CreateRow(currentSheetCount + 1);else//以后没有表头了，所以从开始写，都是基于0的row = sheet.CreateRow(currentSheetCount);currentSheetCount++;for (int j = 0; j < dataTable.Columns.Count; j++){cell = row.CreateCell(j);cell.CellStyle = style;SetCellValues(cell, dataTable.Columns[j].DataType.ToString(), dataTable.Rows[i][j].ToString());}}FileStream fs = new FileStream(excelFileName, FileMode.CreateNew, FileAccess.Write);workbook.Write(fs);fs.Close();return excelFileName;}#endregion}