Excel导入导出NPOI的使用
一、基本概念
整个Excel表格叫工作表:Workbook
工作表包含的叫做页：Sheet
每一行叫做：Row
每一个单元格叫做：Cell
Excel中数字记录的问题
在Excel中字符串都是左对齐，数字是右对齐
在Excel中存数字的时候，数字过大会以科学计数法的方式展示，解决方法是在数字前面加单引号。
使用区域（UsedRange）
用Excel表的时候不一定是从左上角开始，为了减少文件尺寸，只存储使用区域。
二、程序里操作Excel的技术
①OLE Automation
②NPOI
三、NPOI使用方法
1、引入npoi2.1版本最新程序
2、ExcelHelper的写法
namespace WindowsFormsApplication1
{
public class ExcelHelper : IDisposable
{
private string fileName = null; //文件名
private IWorkbook workbook = null;
private FileStream fs = null;
private bool disposed;
public ExcelHelper(string fileName)
{
this.fileName = fileName;
disposed = false;
}
///
/// 将DataTable数据导入到excel中
///
/// 要导入的数据
/// DataTable的列名是否要导入
/// 要导入的excel的sheet的名称
/// 导入数据行数(包含列名那一行)
public int DataTableToExcel(DataTable data, string sheetName, bool isColumnWritten)
{
int i = 0;
int j = 0;
int count = 0;
ISheet sheet = null;
fs = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite);
if (fileName.IndexOf(".xlsx") > 0) // 2007版本
workbook = new XSSFWorkbook();
else if (fileName.IndexOf(".xls") > 0) // 2003版本
workbook = new HSSFWorkbook();
try
{
if (workbook != null)
{
sheet = workbook.CreateSheet(sheetName);
}
else
{
return -1;
}
if (isColumnWritten == true) //写入DataTable的列名
{
IRow row = sheet.CreateRow(0);
for (j = 0; j < data.Columns.Count; ++j)
{
row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
}
count = 1;
}
else
{
count = 0;
}
for (i = 0; i < data.Rows.Count; ++i)
{
IRow row = sheet.CreateRow(count);
for (j = 0; j < data.Columns.Count; ++j)
{
row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
}
++count;
}
workbook.Write(fs); //写入到excel
return count;
}
catch (Exception ex)
{
Console.WriteLine("Exception: " + ex.Message);
return -1;
}
}
///
/// 将excel中的数据导入到DataTable中
///
/// excel工作薄sheet的名称
/// 第一行是否是DataTable的列名
/// 返回的DataTable
public DataTable ExcelToDataTable(string sheetName, bool isFirstRowColumn)
{
ISheet sheet = null;
DataTable data = new DataTable();
int startRow = 0;
try
{
fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
if (fileName.IndexOf(".xlsx") > 0) // 2007版本
workbook = new XSSFWorkbook(fs);
else if (fileName.IndexOf(".xls") > 0) // 2003版本
workbook = new HSSFWorkbook(fs);
if (sheetName != null)
{
sheet = workbook.GetSheet(sheetName);
if (sheet == null) //如果没有找到指定的sheetName对应的sheet，则尝试获取第一个sheet
{
sheet = workbook.GetSheetAt(0);
}
}
else
{
sheet = workbook.GetSheetAt(0);
}
if (sheet != null)
{
IRow firstRow = sheet.GetRow(0);
int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数
if (isFirstRowColumn)
{
for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
{
ICell cell = firstRow.GetCell(i);
if (cell != null)
{
string cellValue = cell.StringCellValue;
if (cellValue != null)
{
DataColumn column = new DataColumn(cellValue);
data.Columns.Add(column);
}
}
}
startRow = sheet.FirstRowNum + 1;
}
else
{
startRow = sheet.FirstRowNum;
}
//最后一列的标号
int rowCount = sheet.LastRowNum;
for (int i = startRow; i <= rowCount; ++i)
{
IRow row = sheet.GetRow(i);
if (row == null) continue; //没有数据的行默认是null
DataRow dataRow = data.NewRow();
for (int j = row.FirstCellNum; j < cellCount; ++j)
{
if (row.GetCell(j) != null) //同理，没有数据的单元格都默认是null
dataRow[j] = row.GetCell(j).ToString();
}
data.Rows.Add(dataRow);
}
}
return data;
}
catch (Exception ex)
{
Console.WriteLine("Exception: " + ex.Message);
return null;
}
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
if (!this.disposed)
{
if (disposing)
{
if (fs != null)
fs.Close();
}
fs = null;
disposed = true;
}
}
}
}namespace WindowsFormsApplication1
{
class Class1
{
static DataTable GenerateData()
{
DataTable data = new DataTable();
for (int i = 0; i < 5; ++i)
{
data.Columns.Add("Columns_" + i.ToString(), typeof(string));
}
for (int i = 0; i < 10; ++i)
{
DataRow row = data.NewRow();
row["Columns_0"] = "item0_" + i.ToString();
row["Columns_1"] = "item1_" + i.ToString();
row["Columns_2"] = "item2_" + i.ToString();
row["Columns_3"] = "item3_" + i.ToString();
row["Columns_4"] = "item4_" + i.ToString();
data.Rows.Add(row);
}
return data;
}
static void PrintData(DataTable data)
{
if (data == null) return;
for (int i = 0; i < data.Rows.Count; ++i)
{
for (int j = 0; j < data.Columns.Count; ++j)
Console.Write("{0} ", data.Rows[i][j]);
Console.Write("\n");
}
}
static void TestExcelWrite(string file)
{
try
{
using (ExcelHelper excelHelper = new ExcelHelper(file))
{
DataTable data = GenerateData();
int count = excelHelper.DataTableToExcel(data, "MySheet", true);
if (count > 0)
Console.WriteLine("Number of imported data is {0} ", count);
}
}
catch (Exception ex)
{
Console.WriteLine("Exception: " + ex.Message);
}
}
static void TestExcelRead(string file)
{
try
{
using (ExcelHelper excelHelper = new ExcelHelper(file))
{
DataTable dt = excelHelper.ExcelToDataTable("MySheet", true);
PrintData(dt);
}
}
catch (Exception ex)
{
Console.WriteLine("Exception: " + ex.Message);
}
}
static void Main(string[] args)
{
string file = "..\\..\\myTest.xlsx";
TestExcelWrite(file);
TestExcelRead(file);
}
}
}