导入Excel和CSV文件

　　读取excel或csv文件中的数据暂时保存在DataTable中， 代码如下：

    public static DataTable ReadDataFromFile(string file, string sheet)

    {

        string strConn = "";

        string extension = Path.GetExtension(file);

        string sqlStr = string.Empty;

        if (extension == ".csv")

        {

            strConn = string.Format("Provider=Microsoft.Jet.OLEDB.4.0;Extended Properties='text;HDR=Yes;FMT=Delimited';Data Source={0}", Path.GetDirectoryName(file));

            sqlStr = string.Format("select * from {0}", Path.GetFileName(file));

        }

        else if (extension == ".xls")

        {

            strConn = string.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties='Excel 8.0;HDR=YES;'", file);

            sqlStr = string.Format("SELECT * FROM [{0}$]", sheet);

        }

        else if (extension == ".xlsx")

        {

            strConn = string.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties=Excel 12.0;", file);

            sqlStr = string.Format("SELECT * FROM [{0}$]", sheet);

        }

        else

        {

            throw new Exception(string.Format("不支持的导入扩展名为{0}的文件！", extension));

        }



        OleDbConnection conn = new OleDbConnection(strConn);

        OleDbDataAdapter myCommand = new OleDbDataAdapter(sqlStr, strConn);

        DataTable dt = new DataTable();

        try

        {

            myCommand.Fill(dt);

        }

        catch (Exception ex)

        {

            throw ex;

        }

        finally

        {

            conn.Close();

        }

        return dt;

    }