NPOI 导入Excel和读取Excel
1、整个Excel表格叫做工作表：WorkBook（工作薄），包含的叫页（工作表）：Sheet；行：Row；单元格Cell。
2、NPOI是POI的C#版本，NPOI的行和列的index都是从0开始
3、POI读取Excel有两种格式一个是HSSF，另一个是XSSF。 HSSF和XSSF的区别如下：
HSSF is the POI Project's pure Java implementation of the Excel '97(-2007) file format.
XSSF is the POI Project's pure Java implementation of the Excel 2007 OOXML (.xlsx) file format.
即：HSSF适用2007以前的版本,XSSF适用2007版本及其以上的。
下面是用NPOI读写Excel的例子：ExcelHelper封装的功能主要是把DataTable中数据写入到Excel中，或者是从Excel读取数据到一个DataTable中。
ExcelHelper类：
using System; using System.Collections.Generic; using System.Linq; using System.Text; using NPOI.SS.UserModel; using NPOI.XSSF.UserModel; using NPOI.HSSF.UserModel; using System.IO; using System.Data; namespace NetUtilityLib { 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; } } } }
补充个方法
/// <summary> /// 获取单元格的值（读取异常的时候调用） /// </summary> /// <param name="Cell"></param> /// <returns></returns> private object GetCellValue(ICell Cell) { object value = null; try { switch (Cell.CellType) { case CellType.Blank: value = Cell.StringCellValue; break; case CellType.String: value = Cell.StringCellValue; break; case CellType.Numeric: value = Cell.NumericCellValue.ToString(); break; case CellType.Boolean: value = Cell.BooleanCellValue; break; case CellType.Formula: value = Cell.RichStringCellValue; break; case CellType.Error: value = Cell.ErrorCellValue; break; case CellType.Unknown: value = Cell.ToString(); break; } } catch (Exception) { value = System.DBNull.Value; } return value; }
测试代码：
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; namespace NPOIExcelExample { class Program { static DataTable GenerateData() { DataTable data = new DataTable(); for (int i = 0; i < 5; ++i) { data.Columns.Add("Columns_" + i.ToString(), typeof(string)); } for (int i = 0; i < 10; ++i) { DataRow row = data.NewRow(); row["Columns_0"] = "item0_" + i.ToString(); row["Columns_1"] = "item1_" + i.ToString(); row["Columns_2"] = "item2_" + i.ToString(); row["Columns_3"] = "item3_" + i.ToString(); row["Columns_4"] = "item4_" + i.ToString(); data.Rows.Add(row); } return data; } static void PrintData(DataTable data) { if (data == null) return; for (int i = 0; i < data.Rows.Count; ++i) { for (int j = 0; j < data.Columns.Count; ++j) Console.Write("{0} ", data.Rows[i][j]); Console.Write("\n"); } } static void TestExcelWrite(string file) { try { using (ExcelHelper excelHelper = new ExcelHelper(file)) { DataTable data = GenerateData(); int count = excelHelper.DataTableToExcel(data, "MySheet", true); if (count > 0) Console.WriteLine("Number of imported data is {0} ", count); } } catch (Exception ex) { Console.WriteLine("Exception: " + ex.Message); } } static void TestExcelRead(string file) { try { using (ExcelHelper excelHelper = new ExcelHelper(file)) { DataTable dt = excelHelper.ExcelToDataTable("MySheet", true); PrintData(dt); } } catch (Exception ex) { Console.WriteLine("Exception: " + ex.Message); } } static void Main(string[] args) { string file = "..\\..\\myTest.xlsx"; TestExcelWrite(file); TestExcelRead(file); } } }
补充调用方法：
HttpPostedFileBase excelFile = Request.Files["fileName"]; //取到上传域 if (null != excelFile) { string fileName = Path.GetFileName(excelFile.FileName); //取到文件的名称 excelFile.SaveAs(Server.MapPath("~/Upload/") + System.IO.Path.GetFileName(excelFile.FileName)); string a = Server.MapPath("~/Upload/" + fileName); ExcelHelper eh = new ExcelHelper(a); if (fileName.Equals("") || null == fileName) { //没有选择文件就上传的话，则跳回到上传页面 return false; }
ExcelHelper eh = new ExcelHelper(a);
参考：http://www.cnblogs.com/luxiaoxun/p/3374992.html
