springboot 如何判断某个bean是否存在

            ApplicationContext ctx = SpringUtil.getContext();
            String[] beanNames = ctx.getBeanDefinitionNames();
            Arrays.sort(beanNames);
            for (String beanName : beanNames) {
                //全部bean
                System.out.println(beanName);
            }

        //某个bean
        try {
           SpringUtil.getContext().getBean("***");
        } catch (Exception e) {
            throw new Exception("*** Bean 不存在");
        }