php excel加密的实现方法有什么?

三个层次

 An example on setting document security:
$objPHPExcel->getSecurity()->setLockWindows(true);
$objPHPExcel->getSecurity()->setLockStructure(true);
$objPHPExcel->getSecurity()->setWorkbookPassword("PHPExcel");

An example on setting worksheet security:
$objPHPExcel->getActiveSheet()->getProtection()->setPassword('PHPExcel');
$objPHPExcel->getActiveSheet()->getProtection()->setSheet(true);
$objPHPExcel->getActiveSheet()->getProtection()->setSort(true);
$objPHPExcel->getActiveSheet()->getProtection()->setInsertRows(true);
$objPHPExcel->getActiveSheet()->getProtection()->setFormatCells(true);

An example on setting cell security:
$objPHPExcel->getActiveSheet()->getStyle('B1')->getProtection()->setLocked(
PHPExcel_Style_Protection::PROTECTION_UNPROTECTED
);