NPoI用于Excel表的导出，导入，

使用NPoI需要引入dll文件，Npoi.dll和lonic.zip.dll.对于开发者主要使用Npoi.Hssf.userModel空间下的，HSSfWorkbook,HSSfSheet,HSSfRow,HSSfCell，对应的借口在Npoi.ss.UserModel空间下的， iworkbook,iSheet,IRow,ICell,分别对应Excel文件，工作薄，行，列。

 

简单演示一下创建一个Workbook对象，添加一个工作表，在工作表中添加一行一列：

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using NPOI.HSSF.UserModel; using NPOI.SS.UserModel;    public class NPOIWrite {      void CreateSheet()      {          IWorkbook workbook = new HSSFWorkbook(); //创建Workbook对象          ISheet sheet = workbook.CreateSheet( "Sheet1" ); //创建工作表          IRow row = sheet.CreateRow(0); //在工作表中添加一行          ICell cell = row.CreateCell(0); //在行中添加一列          cell.SetCellValue( "test" ); //设置列的内容      } }

相应的读取代码：

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using System.IO; using NPOI.HSSF.UserModel; using NPOI.SS.UserModel;    public class NPOIRead {      void GetSheet(Stream stream)      {          IWorkbook workbook = new HSSFWorkbook(stream); //从流内容创建Workbook对象          ISheet sheet = workbook.GetSheetAt(0); //获取第一个工作表          IRow row = sheet.GetRow(0); //获取工作表第一行          ICell cell = row.GetCell(0); //获取行的第一列          string value = cell.ToString(); //获取列的值      } }

使用NPOI导出

从DataTable读取内容来创建Workbook对象：

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public static MemoryStream RenderToExcel(DataTable table) {      MemoryStream ms = new MemoryStream();        using (table)      {          using (IWorkbook workbook = new HSSFWorkbook())          {              using (ISheet sheet = workbook.CreateSheet())              {                  IRow headerRow = sheet.CreateRow(0);                    // handling header.                  foreach (DataColumn column in table.Columns)                      headerRow.CreateCell(column.Ordinal).SetCellValue(column.Caption); //If Caption not set, returns the ColumnName value                    // handling value.                  int rowIndex = 1;                    foreach (DataRow row in table.Rows)                  {                      IRow dataRow = sheet.CreateRow(rowIndex);                        foreach (DataColumn column in table.Columns)                      {                          dataRow.CreateCell(column.Ordinal).SetCellValue(row[column].ToString());                      }                        rowIndex++;                  }                    workbook.Write(ms);                  ms.Flush();                  ms.Position = 0;              }          }      }      return ms; }

使用NPOI导入

需要注意的是，sheet.LastRowNum = sheet.PhysicalNumberOfRows - 1，这里可能存在BUG：当没有数据或只有一行数据时sheet.LastRowNum为0，PhysicalNumberOfRows 表现正常。

这里读取流中的Excel来创建Workbook对象，并转换成DataTable：

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static DataTable RenderFromExcel(Stream excelFileStream) {      using (excelFileStream)      {          using (IWorkbook workbook = new HSSFWorkbook(excelFileStream))          {              using (ISheet sheet = workbook.GetSheetAt(0)) //取第一个表              {                  DataTable table = new DataTable();                    IRow headerRow = sheet.GetRow(0); //第一行为标题行                  int cellCount = headerRow.LastCellNum; //LastCellNum = PhysicalNumberOfCells                  int rowCount = sheet.LastRowNum; //LastRowNum = PhysicalNumberOfRows - 1                    //handling header.                  for ( int i = headerRow.FirstCellNum; i < cellCount; i++)                  {                      DataColumn column = new DataColumn(headerRow.GetCell(i).StringCellValue);                      table.Columns.Add(column);                  }                    for ( int i = (sheet.FirstRowNum + 1); i <= rowCount; i++)                  {                      IRow row = sheet.GetRow(i);                      DataRow dataRow = table.NewRow();                        if (row != null )                      {                          for ( int j = row.FirstCellNum; j < cellCount; j++)                          {                              if (row.GetCell(j) != null )                                  dataRow[j] = GetCellValue(row.GetCell(j));                          }                      }                        table.Rows.Add(dataRow);                  }                  return table;                }          }      } }