最近，由於公司項目中需要將系統內用戶操作的所有日志進行轉存備份，考慮到以後可能還需要還原，所以最後決定將日志數據備份到Excel中。
下面是我項目當中Excel.cs這個類的全部代碼，通過這個類可以很容易地將DataTable中的數據導入到Excel方法中。
首先，必須要下載NPOI.dll這個程序集，
類代碼如下：
代碼如下：
using System;
using NPOI.HSSF;
using NPOI.HPSF;
using NPOI.HSSF.UserModel;
using NPOI.HSSF.Util;
using NPOI.SS.UserModel;
using System.Collections;
using System.IO;
using System.Data;
namespace BackupAttach
{
public class Excel
{
private HSSFWorkbook _workBook;
private ISheet _wbSheet = null;
private DataColumnCollection _columns = null;
private int _col = 0; //total columns
private int _row = 0; //total rows
private int _sheet = 0; //total sheets
private int _sheetRowNum = 65536; //each sheet allow rows
public Excel()
{
InstanceWorkBook();
}
/// <summary>
/// 實例方法
/// </summary>
/// <param name="sheetRowNum">單個表單允許的最大行數</param>
public Excel(int sheetRowNum)
{
_sheetRowNum = sheetRowNum;
InstanceWorkBook();
}
/// <summary>
/// 實例方法
/// </summary>
/// <param name="columns">表頭</param>
public Excel(DataColumnCollection columns)
{
_columns = columns;
InstanceWorkBook();
}
private void InstanceWorkBook()
{
/////cretate WorkBook
_workBook = new HSSFWorkbook();
var dsi = PropertySetFactory.CreateDocumentSummaryInformation();
dsi.Company = "BaiyiTimes";
_workBook.DocumentSummaryInformation = dsi;
////create a entry of SummaryInformation
var si = PropertySetFactory.CreateSummaryInformation();
si.Subject = "Etimes Secure Document System Log Backup";
_workBook.SummaryInformation = si;
}
private DataColumnCollection GetColumns(DataColumnCollection columns)
{
return columns == null || columns.Count == 0 ? _columns : columns;
}
private ISheet GetSheet(ISheet sheet)
{
return sheet == null ? _wbSheet : sheet;
}
private void CreateHeader(ISheet sheet, DataColumnCollection columns)
{
_columns = GetColumns(columns);
/////create row of column
var oRow = sheet.CreateRow(0);
foreach (DataColumn column in _columns)
{
var oCell = oRow.CreateCell(_col);
var style1 = _workBook.CreateCellStyle();
style1.FillForegroundColor = HSSFColor.BLUE.index2;
style1.FillPattern = FillPatternType.SOLID_FOREGROUND;
style1.Alignment = HorizontalAlignment.CENTER;
style1.VerticalAlignment = VerticalAlignment.CENTER;
var font = _workBook.CreateFont();
font.Color = HSSFColor.WHITE.index;
style1.SetFont(font);
oCell.CellStyle = style1;
var name = column.ColumnName;
oCell.SetCellValue(name.ToString());
_col++;
}
///// header belong to rows
_row++;
}
private void CreateHeader(ISheet sheet)
{
CreateHeader(sheet, null);
}
public ISheet CreateSheet()
{
return CreateSheet(null);
}
public ISheet CreateSheet(DataColumnCollection columns)
{
_wbSheet = _workBook.CreateSheet((_sheet + 1).ToString());
CreateHeader(_wbSheet, columns);
_sheet++;
return _wbSheet;
}
public void SetRowValue(DataRowCollection rows, ISheet sheet)
{
_wbSheet = GetSheet(sheet);
foreach (DataRow row in rows)
{
SetRowValue(row);
}
}
public void SetRowValue(DataRowCollection rows)
{
SetRowValue(rows, null);
}
public void SetRowValue(DataRow row)
{
// create a new sheet
if (_row % _sheetRowNum == 0)
{
CreateSheet();
}
var oRow = _wbSheet.CreateRow(_row % _sheetRowNum);
var obj = string.Empty;
var cell = 0;
foreach (DataColumn column in _columns)
{
obj = row[column.ColumnName].ToString();
oRow.CreateCell(cell).SetCellValue(obj);
cell++;
}
_row++;
}
public void SetProtectPassword(string password, string username)
{
_workBook.WriteProtectWorkbook(password, username);
}
public void SaveAs(string filePath)
{
if (File.Exists(filePath)) File.Delete(filePath);
var file = new FileStream(filePath, FileMode.Create);
_workBook.Write(file);
file.Close();
}
}
}
下面給出小Demo共參考：
代碼如下：
public void DataTableToExcel(DataTable dt,string path)
{
//instance excel object
//Excel excel = new Excel(65536);
Excel excel = new Excel();
//create a sheet
excel.CreateSheet(dt.Columns);
//write value into rows
//excel.SetRowValue(dt.Rows);
foreach (DataRow row in dt.Rows)
{
excel.SetRowValue(row);
}
// set excel protected
excel.SetProtectPassword("etimes2011@", "baiyi");
// save excel file to local
excel.SaveAs(path);
}
缺點：如果要導入到Excel中的數據量較多時（幾十萬或者幾百萬行），全部一次性放到DataTable中可能會對內存消耗很大，建議每次導入的數據最好不要超過1000條，可采取分頁查詢的方式將數據導入Excel中。
優點：1997-2003版本的xls中每個表單最大只支持65536行，2010可以支持1048576行，考慮到客戶機上安裝的版本不一樣，故Excel對象每個表單最大支持65536行，當表單到達最大行數時，Excel對象內部會自動創建新表單，在往Excel中寫數據的時候不用考慮這一點，這樣調用的時候更為方便
