转载的文章，方便自己查看。
一、下载NPOI：http://down.gougou.com/down?cid=DAEA322D9D7F934B898077FB01C3A8CB02A746E6
二、项目添加引用；
三、首先把如下代码封装成一个ExcelHelper类；
四、调用方法。
1、导出：分为DataSet多表导出，DataTable单表导出
首先解析一下由DataSet导出Excel
代码
using System;
using System.Data;
using System.IO;
using System.Web;
using NPOI;
using NPOI.HPSF;
using NPOI.HSSF;
using NPOI.HSSF.UserModel;
using NPOI.POIFS;
using NPOI.Util;
using System.Text;
public class ExcelHelper
{
/// <summary>
/// 由DataSet导出Excel
/// </summary>
/// <param name="sourceTable">要导出数据的DataTable</param>
/// <param name="sheetName">工作表名称</param>
/// <returns>Excel工作表</returns>
private static Stream ExportDataSetToExcel(DataSet sourceDs, 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.CreateSheet(sheetNames[i]);
HSSFRow headerRow = sheet.CreateRow(0);
// handling header.
foreach (DataColumn column in sourceDs.Tables[i].Columns)
headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);
// handling value.
int rowIndex = 1;
foreach (DataRow row in sourceDs.Tables[i].Rows)
{
HSSFRow dataRow = sheet.CreateRow(rowIndex);
foreach (DataColumn column in sourceDs.Tables[i].Columns)
{
dataRow.CreateCell(column.Ordinal).SetCellValue(row[column].ToString());
}
rowIndex++;
}
}
workbook.Write(ms);
ms.Flush();
ms.Position = 0;
workbook = null;
return ms;
}
/// <summary>
/// 由DataSet导出Excel
/// </summary>
/// <param name="sourceTable">要导出数据的DataTable</param>
/// <param name="fileName">指定Excel工作表名称</param>
/// <returns>Excel工作表</returns>
public static void ExportDataSetToExcel(DataSet sourceDs, string fileName, string sheetName)
{
MemoryStream ms = ExportDataSetToExcel(sourceDs, sheetName) as MemoryStream;
HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + fileName);
HttpContext.Current.Response.BinaryWrite(ms.ToArray());
HttpContext.Current.Response.End();
ms.Close();
ms = null;
}
由DataTable导出Excel
代码
/// <summary>
/// 由DataTable导出Excel
/// </summary>
/// <param name="sourceTable">要导出数据的DataTable</param>
/// <returns>Excel工作表</returns>
private static Stream ExportDataTableToExcel(DataTable sourceTable, string sheetName)
{
HSSFWorkbook workbook = new HSSFWorkbook();
MemoryStream ms = new MemoryStream();
HSSFSheet sheet = workbook.CreateSheet(sheetName);
HSSFRow headerRow = sheet.CreateRow(0);
// handling header.
foreach (DataColumn column in sourceTable.Columns)
headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);
// handling value.
int rowIndex = 1;
foreach (DataRow row in sourceTable.Rows)
{
HSSFRow dataRow = sheet.CreateRow(rowIndex);
foreach (DataColumn column in sourceTable.Columns)
{
dataRow.CreateCell(column.Ordinal).SetCellValue(row[column].ToString());
}
rowIndex++;
}
workbook.Write(ms);
ms.Flush();
ms.Position = 0;
sheet = null;
headerRow = null;
workbook = null;
return ms;
}
/// <summary>
/// 由DataTable导出Excel
/// </summary>
/// <param name="sourceTable">要导出数据的DataTable</param>
/// <param name="fileName">指定Excel工作表名称</param>
/// <returns>Excel工作表</returns>
public static void ExportDataTableToExcel(DataTable sourceTable, string fileName, string sheetName)
{
MemoryStream ms = ExportDataTableToExcel(sourceTable, sheetName) as MemoryStream;
HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + fileName);
HttpContext.Current.Response.BinaryWrite(ms.ToArray());
HttpContext.Current.Response.End();
ms.Close();
ms = null;
}
2、导入
由Excel导入DataTable
代码
/// <summary>
/// 由Excel导入DataTable
/// </summary>
/// <param name="excelFileStream">Excel文件流</param>
/// <param name="sheetName">Excel工作表名称</param>
/// <param name="headerRowIndex">Excel表头行索引</param>
/// <returns>DataTable</returns>
public static DataTable ImportDataTableFromExcel(Stream excelFileStream, string sheetName, int headerRowIndex)
{
HSSFWorkbook workbook = new HSSFWorkbook(excelFileStream);
HSSFSheet sheet = workbook.GetSheet(sheetName);
DataTable table = new DataTable();
HSSFRow headerRow = sheet.GetRow(headerRowIndex);
int cellCount = headerRow.LastCellNum;
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 <= sheet.LastRowNum; i++)
{
HSSFRow row = sheet.GetRow(i);
DataRow dataRow = table.NewRow();
for (int j = row.FirstCellNum; j < cellCount; j++)
dataRow[j] = row.GetCell(j).ToString();
}
excelFileStream.Close();
workbook = null;
sheet = null;
return table;
}
/// <summary>
/// 由Excel导入DataTable
/// </summary>
/// <param name="excelFilePath">Excel文件路径，为物理路径。</param>
/// <param name="sheetName">Excel工作表名称</param>
/// <param name="headerRowIndex">Excel表头行索引</param>
/// <returns>DataTable</returns>
public static DataTable ImportDataTableFromExcel(string excelFilePath, string sheetName, int headerRowIndex)
{
using (FileStream stream = System.IO.File.OpenRead(excelFilePath))
{
return ImportDataTableFromExcel(stream, sheetName, headerRowIndex);
}
}
/// <summary>
/// 由Excel导入DataTable
/// </summary>
/// <param name="excelFileStream">Excel文件流</param>
/// <param name="sheetName">Excel工作表索引</param>
/// <param name="headerRowIndex">Excel表头行索引</param>
/// <returns>DataTable</returns>
public static DataTable ImportDataTableFromExcel(Stream excelFileStream, int sheetIndex, int headerRowIndex)
{
HSSFWorkbook workbook = new HSSFWorkbook(excelFileStream);
HSSFSheet sheet = workbook.GetSheetAt(sheetIndex);
DataTable table = new DataTable();
HSSFRow headerRow = sheet.GetRow(headerRowIndex);
int cellCount = headerRow.LastCellNum;
for (int i = headerRow.FirstCellNum; i < cellCount; i++)
{
if (headerRow.GetCell(i) == null || headerRow.GetCell(i).StringCellValue.Trim() == "")
{
// 如果遇到第一个空列，则不再继续向后读取
cellCount = i + 1;
break;
}
DataColumn column = new DataColumn(headerRow.GetCell(i).StringCellValue);
table.Columns.Add(column);
}
for (int i = (sheet.FirstRowNum + 1); i <= sheet.LastRowNum; i++)
{
HSSFRow row = sheet.GetRow(i);
if (row == null || row.GetCell(0) == null || row.GetCell(0).ToString().Trim() == "")
{
// 如果遇到第一个空行，则不再继续向后读取
break;
}
DataRow dataRow = table.NewRow();
for (int j = row.FirstCellNum; j < cellCount; j++)
{
dataRow[j] = row.GetCell(j);
}
table.Rows.Add(dataRow);
}
excelFileStream.Close();
workbook = null;
sheet = null;
return table;
}
/// <summary>
/// 由Excel导入DataTable
/// </summary>
/// <param name="excelFilePath">Excel文件路径，为物理路径。</param>
/// <param name="sheetName">Excel工作表索引</param>
/// <param name="headerRowIndex">Excel表头行索引</param>
/// <returns>DataTable</returns>
public static DataTable ImportDataTableFromExcel(string excelFilePath, int sheetIndex, int headerRowIndex)
{
using (FileStream stream = System.IO.File.OpenRead(excelFilePath))
{
return ImportDataTableFromExcel(stream, sheetIndex, headerRowIndex);
}
}
有Excel导入DataSet
代码
/// <summary>
/// 由Excel导入DataSet，如果有多个工作表，则导入多个DataTable
/// </summary>
/// <param name="excelFileStream">Excel文件流</param>
/// <param name="headerRowIndex">Excel表头行索引</param>
/// <returns>DataSet</returns>
public static DataSet ImportDataSetFromExcel(Stream excelFileStream, int headerRowIndex)
{
DataSet ds = new DataSet();
HSSFWorkbook workbook = new HSSFWorkbook(excelFileStream);
for (int a = 0, b = workbook.NumberOfSheets; a < b; a++)
{
HSSFSheet sheet = workbook.GetSheetAt(a);
DataTable table = new DataTable();
HSSFRow headerRow = sheet.GetRow(headerRowIndex);
int cellCount = headerRow.LastCellNum;
for (int i = headerRow.FirstCellNum; i < cellCount; i++)
{
if (headerRow.GetCell(i) == null || headerRow.GetCell(i).StringCellValue.Trim() == "")
{
// 如果遇到第一个空列，则不再继续向后读取
cellCount = i + 1;
break;
}
DataColumn column = new DataColumn(headerRow.GetCell(i).StringCellValue);
table.Columns.Add(column);
}
for (int i = (sheet.FirstRowNum + 1); i <= sheet.LastRowNum ; i++)
{
HSSFRow row = sheet.GetRow(i);
if (row == null || row.GetCell(0) == null || row.GetCell(0).ToString().Trim() == "")
{
// 如果遇到第一个空行，则不再继续向后读取
break;
}
DataRow dataRow = table.NewRow();
for (int j = row.FirstCellNum; j < cellCount; j++)
{
if (row.GetCell(j) != null)
{
dataRow[j] = row.GetCell(j).ToString();
}
}
table.Rows.Add(dataRow);
}
ds.Tables.Add(table);
}
excelFileStream.Close();
workbook = null;
return ds;
}
/// <summary>
/// 由Excel导入DataSet，如果有多个工作表，则导入多个DataTable
/// </summary>
/// <param name="excelFilePath">Excel文件路径，为物理路径。</param>
/// <param name="headerRowIndex">Excel表头行索引</param>
/// <returns>DataSet</returns>
public static DataSet ImportDataSetFromExcel(string excelFilePath, int headerRowIndex)
{
using (FileStream stream = System.IO.File.OpenRead(excelFilePath))
{
return ImportDataSetFromExcel(stream, headerRowIndex);
}
}
另外为导入补充一点知识：
1、将Excel的列索引转换为列名，列索引从0开始，列名从A开始。如第0列为A，第1列为B...
代码
/// <summary>
/// 将Excel的列索引转换为列名，列索引从0开始，列名从A开始。如第0列为A，第1列为B...
/// </summary>
/// <param name="index">列索引</param>
/// <returns>列名，如第0列为A，第1列为B...</returns>
public static string ConvertColumnIndexToColumnName(int index)
{
index = index + 1;
int system = 26;
char[] digArray = new char[100];
int i = 0;
while (index > 0)
{
int mod = index % system;
if (mod == 0) mod = system;
digArray[i++] = (char)(mod - 1 + 'A');
index = (index - 1) / 26;
}
StringBuilder sb = new StringBuilder(i);
for (int j = i - 1; j >= 0; j--)
{
sb.Append(digArray[j]);
}
return sb.ToString();
}
2、当从Excel获取年月日时，会从在一定的问题，应该在一下代码中，可以想到存在的问题，所以我们可以写个方法封装一下：
代码
/// <summary>
/// 转化日期
/// </summary>
/// <param name="date">日期</param>
/// <returns></returns>
public static DateTime ConvertDate(string date)
{
DateTime dt = new DateTime();
string[] time = date.Split('-');
int year = Convert.ToInt32(time[2]);
int month = Convert.ToInt32(time[0]);
int day = Convert.ToInt32(time[1]);
string years = Convert.ToString(year);
string months = Convert.ToString(month);
string days = Convert.ToString(day);
if(months.Length == 4)
{
dt = Convert.ToDateTime(date);
}
else
{
string rq = "";
if(years.Length == 1)
{
years = "0" + years;
}
if(months.Length == 1)
{
months = "0" + months;
}
if(days.Length == 1)
{
days = "0" + days;
}
rq = "20" + years + "-" + months + "-" + days;
dt = Convert.ToDateTime(rq);
}
return dt;
}
}