如何通过<a>元素实现PHPExcel下载？

require_once 'PHPExcel/PHPExcel.php';

$objPHPExcel = new PHPExcel();
$objPHPExcel->getProperties()->setTitle("PHPExcel Download")->setDescription("PHPExcel Download");
$objPHPExcel->setActiveSheetIndex(0)->setCellValue('A1', 'Column 1')->setCellValue('B1', 'Column 2');

$data = array(
    array('Data 1', 'Data 2'),
    array('Data 3', 'Data 4'),
);

$row = 2;
foreach ($data as $item) {
    $objPHPExcel->setActiveSheetIndex(0)->setCellValue('A'.$row, $item[0])->setCellValue('B'.$row, $item[1]);
    $row++;
}

$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
$objWriter->save('php://output');

header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
header('Content-Disposition: attachment;filename="PHPExcelDownload.xlsx"');
header('Cache-Control: max-age=0');

$objWriter->save('php://output');

<a href="download.php">点击下载Excel文件</a>