C# 读取EXCEL文件的三种经典方法

//txt文件名
stringfn=DateTime.Now.ToString("yyyyMMddHHmmss")+"-"+"PO014"+".txt";

OleDbConnectioncon=newOleDbConnection(conStr);
con.Open();
stringsql="selectITEM,REQD_DATE,QTY,PUR_FLG,PO_NUMfromTSD_PO014";
//OleDbCommandmycom=newOleDbCommand("select*fromTSD_PO014",mycon);
//OleDbDataReadermyreader=mycom.ExecuteReader();//也可以用Reader读取数据
DataSetds=newDataSet();
OleDbDataAdapteroda=newOleDbDataAdapter(sql,con);
oda.Fill(ds,"PO014");
DataTabledt=ds.Tables[0];

FileStreamfs=newFileStream(Server.MapPath("download/"+fn),FileMode.Create,FileAccess.ReadWrite);
StreamWriterstrmWriter=newStreamWriter(fs);//存入到文本文件中

//把标题写入.txt文件中
//for(inti=0;i<dt.Columns.Count;i++)
//{
//strmWriter.Write(dt.Columns[i].ColumnName+"");
//}

foreach(DataRowdrindt.Rows)
{
stringstr0,str1,str2,str3;
stringstr="|";//数据用"|"分隔开
str0=dr[0].ToString();
str1=dr[1].ToString();
str2=dr[2].ToString();
str3=dr[3].ToString();
str4=dr[4].ToString().Trim();
strmWriter.Write(str0);
strmWriter.Write(str);
strmWriter.Write(str1);
strmWriter.Write(str);
strmWriter.Write(str2);
strmWriter.Write(str);
strmWriter.Write(str3);
strmWriter.WriteLine();//换行
}
strmWriter.Flush();
strmWriter.Close();
if(con.State==ConnectionState.Open)
{
con.Close();
}