使用NPOI将DataGridView的数据导出EXCEL

加载NPOI.DLL ，引用这两个命名空间
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;

#region NPOI DataGridView 导出 EXCEL
/// <summary>
/// NPOI DataGridView 导出 EXCEL
/// </summary>
/// <param name="fileName"> 默认保存文件名</param>
/// <param name="dgv">DataGridView</param>
/// <param name="fontname">字体名称</param>
/// <param name="fontsize">字体大小</param>
public void ExportExcel(string fileName, DataGridView dgv, string fontname, short fontsize)
{
//检测是否有数据
if (dgv.SelectedRows.Count == 0) return;
//创建主要对象
HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = (HSSFSheet)workbook.CreateSheet("Weight");
//设置字体，大小，对齐方式
HSSFCellStyle style = (HSSFCellStyle)workbook.CreateCellStyle();
HSSFFont font = (HSSFFont)workbook.CreateFont();
font.FontName = fontname;
font.FontHeightInPoints = fontsize;
style.SetFont(font);
style.Alignment = NPOI.SS.UserModel.HorizontalAlignment.Center; //居中对齐
//添加表头
HSSFRow dataRow = (HSSFRow)sheet.CreateRow(0);
for (int i = 0; i < dgv.Columns.Count; i++)
{
dataRow.CreateCell(i).SetCellValue(dgv.Columns[i].HeaderText);
dataRow.GetCell(i).CellStyle = style;
}
//注释的这行是设置筛选的
//sheet.SetAutoFilter(new CellRangeAddress(0, dgv.Columns.Count, 0, dgv.Columns.Count));
//添加列及内容
for (int i = 0; i < dgv.Rows.Count; i++)
{
dataRow = (HSSFRow)sheet.CreateRow(i + 1);
for (int j = 0; j < dgv.Columns.Count; j++)
{
string ValueType = dgv.Rows[i].Cells[j].Value.GetType().ToString();
string Value = dgv.Rows[i].Cells[j].Value.ToString();
switch (ValueType)
{
case "System.String"://字符串类型
dataRow.CreateCell(j).SetCellValue(Value);
break;
case "System.DateTime"://日期类型
System.DateTime dateV;
System.DateTime.TryParse(Value, out dateV);
dataRow.CreateCell(j).SetCellValue(dateV);
break;
case "System.Boolean"://布尔型
bool boolV = false;
bool.TryParse(Value, out boolV);
dataRow.CreateCell(j).SetCellValue(boolV);
break;
case "System.Int16"://整型
case "System.Int32":
case "System.Int64":
case "System.Byte":
int intV = 0;
int.TryParse(Value, out intV);
dataRow.CreateCell(j).SetCellValue(intV);
break;
case "System.Decimal"://浮点型
case "System.Double":
double doubV = 0;
double.TryParse(Value, out doubV);
dataRow.CreateCell(j).SetCellValue(doubV);
break;
case "System.DBNull"://空值处理
dataRow.CreateCell(j).SetCellValue("");
break;
default:
dataRow.CreateCell(j).SetCellValue("");
break;
}
dataRow.GetCell(j).CellStyle = style;
//设置宽度
sheet.SetColumnWidth(j, (Value.Length + 10) * 256);
}
}
//保存文件
string saveFileName = "";
SaveFileDialog saveDialog = new SaveFileDialog();
saveDialog.DefaultExt = "xls";
saveDialog.Filter = "Excel文件|*.xls";
saveDialog.FileName = fileName;
MemoryStream ms = new MemoryStream();
if (saveDialog.ShowDialog() == DialogResult.OK)
{
saveFileName = saveDialog.FileName;
if (!CheckFiles(saveFileName))
{
MessageBox.Show("文件被站用，请关闭文件 " + saveFileName);
workbook = null;
ms.Close();
ms.Dispose();
return;
}
workbook.Write(ms);
FileStream file = new FileStream(saveFileName, FileMode.Create);
workbook.Write(file);
file.Close();
workbook = null;
ms.Close();
ms.Dispose();
MessageBox.Show(fileName + " 保存成功", "提示", MessageBoxButtons.OK);
}
else
{
workbook = null;
ms.Close();
ms.Dispose();
}
}
#endregion

#region 检测文件被占用
[DllImport("kernel32.dll")]
public static extern IntPtr _lopen(string lpPathName, int iReadWrite);
[DllImport("kernel32.dll")]
public static extern bool CloseHandle(IntPtr hObject);
public const int OF_READWRITE = 2;
public const int OF_SHARE_DENY_NONE = 0x40;
public readonly IntPtr HFILE_ERROR = new IntPtr(-1);
/// <summary>
/// 检测文件被占用
/// </summary>
/// <param name="FileNames">要检测的文件路径</param>
/// <returns></returns>
public bool CheckFiles(string FileNames)
{
if (!File.Exists(FileNames))
{
//文件不存在
return true;
}
IntPtr vHandle = _lopen(FileNames, OF_READWRITE | OF_SHARE_DENY_NONE);
if (vHandle == HFILE_ERROR)
{
//文件被占用
return false;
}
//文件没被占用
CloseHandle(vHandle);
return true;
}
#endregion