java.lang.IllegalArgumentException: node to traverse cannot be null!

查看HQL的语句是否写错了，是否有在From后面加空格。我就是没有加空格报了错误！

        return sessionFactory.getCurrentSession().createQuery("from " + " "+clazzName).list();

<script type="text/javascript"> $(function () { $('pre.prettyprint code').each(function () { var lines = $(this).text().split('\n').length; var $numbering = $('<ul/>').addClass('pre-numbering').hide(); $(this).addClass('has-numbering').parent().append($numbering); for (i = 1; i <= lines; i++) { $numbering.append($('<li/>').text(i)); }; $numbering.fadeIn(1700); }); }); </script>