PHPExcel: .xlsの指定したシートのデータのみ読み込む例

gistfile1.php

<?php
require_once 'PHPExcel.php';

$filename = 'Book1.xls';
$sheet_name = 'Sheet1';

$reader = PHPExcel_IOFactory::createReader('EXCEL5');
$reader->setReadDataOnly(true);
$reader->setLoadSheetsOnly(array($sheet_name));

$excel = $reader->load($filename);
$sheet = $excel->getSheet(0);
echo $sheet->getCell('A1')->getValue();