1.InitializingBean
失效此接口的类,在初始化完成之后,会自动调用afterPropertiesSet()方法,但是在init-method方法之后(如果配置)
@Componentpublic class InitializingBeanTest implements InitializingBean { @Override public void afterPropertiesSet() throws Exception { System.out.println("afterPropertiesSet 被调用"); }}
2.BeanPostProcessor
bean后置处理器,它是用来拦截所有 bean 的初始化的,在 bean 的初始化之前,和初始化之后做一些事情。这点从 BeanPostProcessor 接口的定义也可以看出来,它里面就两个方法:postProcessBeforeInitialization 和 postProcessAfterInitialization。
2.1:后置处理器的postProcessorBeforeInitailization方法是在bean实例化,依赖注入之后及自定义初始化方法(例如:配置文件中bean标签添加init-method属性指定Java类中初始化方法、
@PostConstruct注解指定初始化方法,Java类实现InitailztingBean接口)之前调用
2.2:后置处理器的postProcessorAfterInitailization方法是在bean实例化、依赖注入及自定义初始化方法之后调用
@Componentpublic class BeanPostProcessorTest implements BeanPostProcessor { public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { System.out.println("后置处理器处理bean=【"+beanName+"】开始"); return bean; } public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { System.out.println("后置处理器处理bean=【"+beanName+"】完毕"); return bean; }}
3.ApplicationContextAware
当一个类实现了这个接口之后,这个类就可以方便的获得ApplicationContext对象,然后从applicationContext对象中利用getBean()获取容器中的bean
@Componentpublic class SpringContextHelper implements ApplicationContextAware { private static ApplicationContext applicationContext; @Override public void setApplicationContext(ApplicationContext context) throws BeansException { applicationContext = context; } public static T getInstance(String beanName, Class beanType) { return applicationContext.getBean(beanName, beanType); } public static T getInstance(Class bean) { return applicationContext.getBean(bean); }}
4.BeanFactoryAware
同ApplicationContextAware对象一样,实现此接口可以获取到BeanFactory对象,然后利用getBean获取我们需要bean
@Servicepublic class BeanFactoryHelper implements BeanFactoryAware { private static BeanFactory beanFactory; @Override public void setBeanFactory(BeanFactory beanFactory) throws BeansException { this.beanFactory = beanFactory; } public static Object getBean(String beanName){ if(beanFactory == null){ throw new NullPointerException("BeanFactory is null!"); } return beanFactory.getBean(beanName); } }
5.ApplicationRunner
在项目完全启动后,调用实现此接口的方法。
@Componentpublic class CommonRunner implements ApplicationRunner { @Override public void run(ApplicationArguments args) throws Exception { System.out.println("启动后执行。。。。。"); }}
6.@PostConstruct
在bean初始化之前调用,具体和afterPropertiesSet(),还有init-method调用顺序,可以看下spring的生命周期