/**
     * 清空用户关联权限认证，待下次使用时重新加载
     */
    public void clearCachedAuthorizationInfo(Principal principal) {
        Subject subject = SecurityUtils.getSubject();   
       // String realmName = subject.getPrincipals().getRealmNames().iterator().next();   
        SimplePrincipalCollection principals = new SimplePrincipalCollection(principal,getName());   
        subject.runAs(principals);   
        clearCachedAuthorizationInfo(subject.getPrincipals());
        subject.releaseRunAs();
    }