使用NPOI访问、控制Excel
工作中经常使用Excel，很多重复的数据操作或者检查都丢给程序做是最好的。
最一开始选择使用Com组件来作业，水平有限，使用效果不太理想，全是动态类型真的用起来有点累，异常处理也要小心谨慎。
之后选择了OleDB进行excel操作，但是把Excel作为数据库操作，会有下面的问题：
关系数据库第一范式规定了对某一列中的数据只能有一种属性，因此当excel中某列既有string型又有Numeric型数据时，只能读到其中的一种，导致数据读入不全。
最终选择了NPOI作为解决方案，目前效果比较理想，写了个助手方法，方便日常使用。
using NPOI.HSSF.UserModel; using NPOI.SS.UserModel; using NPOI.XSSF.UserModel; using System; using System.Collections.Generic; using System.Data; using System.IO; using System.Linq; namespace Rainbow.Core { /// <summary> /// Helper for NOPI to operate excel files. /// </summary> public static class NPOIHelper { #region public methods /// <summary> /// Get the IWorkbook of the dest excel file. /// </summary> /// <param name="filePath">The dest file path.</param> /// <exception cref="RainstormException"></exception> /// <returns></returns> static public IWorkbook GetDestWorkBook(string filePath) { CoreUtility.CheckExcelFile(filePath); IWorkbook workBook = null; FunctionExcuteHelper.ExcuteIOFunction(() => { using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read)) { if (Path.GetExtension(filePath) == ".xls") workBook = new HSSFWorkbook(fs); else workBook = new XSSFWorkbook(fs); } }); return workBook; } /// <summary> /// Get the ISheet of the dest sheet. /// </summary> /// <param name="filePath">The dest file path.</param> /// <param name="sheetName">The dest sheet name.</param> /// <returns></returns> static public ISheet GetDestWorkSheet(string filePath, string sheetName) { IWorkbook workBook = GetDestWorkBook(filePath); ISheet workSheet = null; workSheet = GetDestWorkSheet(workBook, sheetName); return workSheet; } /// <summary> /// Get the ISheet of the dest sheet. /// </summary> /// <param name="workBook">The IWorkbook dest file.</param> /// <param name="sheetName">The dest sheet name.</param> /// <returns></returns> static public ISheet GetDestWorkSheet(IWorkbook workBook, string sheetName) { ISheet workSheet = null; workSheet = workBook.GetSheet(sheetName); if (workSheet == null) throw new Exception(string.Format("There is no sheet named <{0}> in the excel.", sheetName)); return workSheet; } /// <summary> /// Read dest sheet as a DataTable. /// The column is named with 'F1 F2 ...' /// </summary> /// <param name="filePath">The dest file path.</param> /// <param name="sheetName">The dest sheet name.</param> /// <param name="startRow">Start line number.</param> /// <returns></returns> static public DataTable ReadSheetAsDataTable(string filePath, string sheetName, int startRow = 0) { ISheet sheet = GetDestWorkSheet(filePath, sheetName); return GetDataTableFromISheet(sheet, startRow); } /// <summary> /// Read dest excel as a DataTable. /// The tables are named with sheet name. /// </summary> /// <param name="filePath"></param> /// <returns></returns> static public DataSet ReadExcelAsDataSet(string filePath) { string fileName = System.IO.Path.GetFileNameWithoutExtension(filePath); DataSet ds = new DataSet(fileName); IWorkbook workBook = GetDestWorkBook(filePath); for (int i = 0; i < workBook.NumberOfSheets; i++) ds.Tables.Add(GetDataTableFromISheet(workBook.GetSheetAt(i))); return ds; } /// <summary> /// Get the string value of the ICell. /// </summary> /// <param name="cell">Dest ICell.</param> /// <returns></returns> static public string GetDestCellStringValue(ICell cell) { if (cell == null) { return string.Empty; } string result = string.Empty; switch (cell.CellType) { case CellType.String: result = cell.StringCellValue; break; case CellType.Numeric: if (DateUtil.IsCellDateFormatted(cell)) result = cell.DateCellValue.ToShortDateString(); else result = cell.NumericCellValue.ToString(); break; default: result = string.Empty; break; } return result; } /// <summary> /// Set dest cell a string value. /// </summary> /// <typeparam name="TValue">string ,int or any Type overrided ToString().</typeparam> /// <param name="row"></param> /// <param name="cellPosition"></param> /// <param name="value"></param> static public void SetDestCellStringValue<TValue>(IRow row, int cellPosition, TValue value) { if (row == null) throw new Exception("The row is a NULL row."); if (row.GetCell(cellPosition) == null) row.CreateCell(cellPosition).SetCellValue(value.ToString()); else row.GetCell(cellPosition).SetCellValue(value.ToString()); } /// <summary> /// Set dest cell a string value and dest style. /// </summary> /// <typeparam name="TValue"></typeparam> /// <param name="row"></param> /// <param name="cellPosition"></param> /// <param name="style"></param> /// <param name="value"></param> static public void SetDestCellStringValueAndStyle<TValue>(IRow row, int cellPosition, ICellStyle style, TValue value) { SetDestCellStringValue<TValue>(row, cellPosition, value); ICell cell = row.GetCell(cellPosition); cell.CellStyle = style; } /// <summary> /// Get all sheet names as a list. /// </summary> /// <param name="filePath"></param> /// <returns></returns> static public List<string> GetAllSheetNames(string filePath) { return GetAllSheetNames(GetDestWorkBook(filePath)); } /// <summary> /// Get all sheet names as a list. /// </summary> /// <param name="workBook"></param> /// <returns></returns> static public List<string> GetAllSheetNames(IWorkbook workBook) { List<string> result = new List<string>(); for (int i = 0; i < workBook.NumberOfSheets; i++) result.Add(workBook.GetSheetName(i)); return result; } /// <summary> /// Save workBook to dest excel file. /// </summary> /// <param name="filePath"></param> /// <param name="workBook"></param> static public void SaveWorkBookToExcelFile(IWorkbook workBook, string filePath) { CoreUtility.CheckExcelFile(filePath); FunctionExcuteHelper.ExcuteIOFunction(() => { using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite)) workBook.Write(fs); }); } /// <summary> /// Convert a DataSet to a excel file. /// </summary> /// <param name="dataSet"></param> /// <param name="filePath"></param> static public void DataSetToExcel(DataSet dataSet, string filePath) { CoreUtility.CheckExcelFile(filePath); var ext = Path.GetExtension(filePath); FunctionExcuteHelper.ExcuteIOFunction(() => { var workbook = DataSetToWorkBook(dataSet, ext); using (FileStream fs = new FileStream(filePath, FileMode.Create, FileAccess.Write)) { workbook.Write(fs); } }); } /// <summary> /// Read dest ISheet as a DataTable. /// The column is named with 'F1 F2 ...' /// </summary> /// <param name="workSheet"></param> /// <param name="startRow"></param> /// <returns></returns> static public DataTable GetDataTableFromISheet(ISheet workSheet, int startRow = 0) { if (workSheet == null) throw new Exception("Dest work sheet does not exists."); DataTable result = new DataTable(workSheet.SheetName); int columnNumber = GuessSheetColumnNumber(workSheet); for (int i = 0; i < columnNumber; i++) result.Columns.Add(string.Format("F{0}", i + 1), typeof(string)); for (int i = startRow; i <= workSheet.LastRowNum; i++) { IRow row = workSheet.GetRow(i); if (row == null) continue; result.Rows.Add(ConvertIRowToDataRow(row, result)); } return result; } #endregion #region private methods static private int GuessSheetColumnNumber(ISheet workSheet) { IRow headerRow = workSheet.GetRow(workSheet.FirstRowNum); IRow middleRow = workSheet.GetRow(workSheet.LastRowNum / 2); IRow lastRow = workSheet.GetRow(workSheet.LastRowNum); int result = 0; result = Math.Max(headerRow.LastCellNum, middleRow.LastCellNum); result = Math.Max(result, lastRow.LastCellNum); return result; } static private DataRow ConvertIRowToDataRow(IRow row, DataTable dataTable) { DataRow dr = dataTable.NewRow(); for (int i = 0; i < dataTable.Columns.Count; i++) dr[i] = GetDestCellStringValue(row.GetCell(i)); return dr; } static private void DataTableToWorkSheet(DataTable dataTable, ISheet sheet) { IRow headerRow = sheet.CreateRow(0); //Set the header foreach (DataColumn dc in dataTable.Columns) headerRow.CreateCell(dc.Ordinal).SetCellValue(dc.ColumnName); //Set the content for (int i = 0; i < dataTable.Rows.Count; i++) { IRow row = sheet.CreateRow(i + 1); for (int j = 0; j < dataTable.Columns.Count; j++) row.CreateCell(j).SetCellValue(dataTable.Rows[i][j].ToString()); } } static private IWorkbook DataSetToWorkBook(DataSet dataSet, string extension) { IWorkbook workBook = null; if (extension == ".xls") workBook = new HSSFWorkbook(); else workBook = new XSSFWorkbook(); try { foreach (DataTable dt in dataSet.Tables) { ISheet sheet = null; sheet = workBook.CreateSheet(dt.TableName); DataTableToWorkSheet(dt, sheet); } } catch (Exception) { throw new Exception( string.Format("Error while converting DataSet <{0}> to WorkBook.", dataSet.DataSetName)); } return workBook; } #endregion } }