获取Excel数据及Sheet的方法

/// <summary>
        /// 将Excel数据转为DataSet
        /// </summary>
        /// <param name="filepath"></param>
        /// <param name="sheetname"></param>
        /// <returns></returns>
        public DataSet ExcelDataSource(string filepath, string sheetname)
        {
            string strConn;
            string str_name = filepath.Substring(filepath.Length - 5, 5).Split('.')[1].ToString();
            if (str_name == "xls")
            {
                strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + filepath + ";Extended Properties=Excel 8.0;";
            }
            else
            {
                strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + filepath + ";Extended Properties='Excel 12.0;HDR=Yes;IMEX=1'";
            }
            OleDbConnection conn = new OleDbConnection(strConn);
            OleDbDataAdapter oada = new OleDbDataAdapter("select * from [" + sheetname + "]", strConn);
            DataSet ds = new DataSet();
            oada.Fill(ds);
            return ds;
        }

        /// <summary>
        /// 获取Excel中的Sheet名称
        /// </summary>
        /// <param name="filepath"></param>
        /// <returns></returns>
        public ArrayList ExcelSheetName(string filepath)
        {
            ArrayList al = new ArrayList();
            string strConn;
            string str_name = filepath.Substring(filepath.Length - 5, 5).Split('.')[1].ToString();
            if (str_name == "xls")
            {
                strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + filepath + ";Extended Properties=Excel 8.0;";
            }
            else
            {
                strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + filepath + ";Extended Properties='Excel 12.0;HDR=Yes;IMEX=1'";
            }
            OleDbConnection conn = new OleDbConnection(strConn);
            conn.Open();
            DataTable sheetNames = conn.GetOleDbSchemaTable
            (System.Data.OleDb.OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });
            conn.Close();
            foreach (DataRow dr in sheetNames.Rows)
            {
                al.Add(dr[2]);
            }
            return al;
        }