public static Stream DataSetToExcel(DataSet _SourceDt,string _sheetName)
    {
      HSSFWorkbook workbook = new HSSFWorkbook();
      MemoryStream MS = new MemoryStream();
      string [] sheetNames= _sheetName.Split(',');
      for(int i = 0; i <sheetNames.Length;i++)
      {
        HSSFSheet sheet = workbook.Cretesheet(sheetNames[i]);
        HSSFRow headRow = sheet.CreateRow(0);
        foreach(DataColumn column in _SourceDt.Table[i].cloumns)
        headRow.createCell(column.Ordinal).SetCellValue(column.Column.Name);
        int rowIndex =1;
        foreach(DataRow row in _SourceDt.Tables[i].Rows)
        {
          HSSFRow dataRow = sheet.CreateRow(rowIndex);
          foreach(DataColumn column in _SourceDt.Tables[i].Columns)
          {
            dataRow.CreateCell(column.Ordinal).SetCellValue(row[column].ToString());
          }
          rowIndex++;
        }
      }
      workbook.write(MS);
      MS.Flush();
      MS.Position = 0;
      workbook = null;
      return MS;
    }

   DataTable dt = new DataTable();
      DataSet DataTemp = new DataSet();
      dt.Columns.Add("列名1",string);
      dt.Columns.Add("列名2",string );
      for(int i = 0;i<3;i++)
      {
        DataRow DR = dt.NewRow();
        DR["列名1"] = "DATA1";
        DR["列名2"] = "DATA1";
        dt.Rows.Add(DR);
      }
      DataTemp.Tables.Add(dt);