Spring-2Spring Bean 的生命周期
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Spring框架中,一旦把一个Bean纳入Spring IOC容器之中,这个Bean的生命周期就会交由容器进行管理,一般担当管理角色的是BeanFactory或者ApplicationContext,认识一下Bean的生命周期活动,对更好的利用它有很大的帮助:
下面以BeanFactory为例,说明一个Bean的生命周期活动
- Bean的建立, 由BeanFactory读取Bean定义文件,并生成各个实例
- Setter注入,执行Bean的属性依赖注入
- BeanNameAware的setBeanName(), 如果实现该接口,则执行其setBeanName方法
- BeanFactoryAware的setBeanFactory(),如果实现该接口,则执行其setBeanFactory方法
- BeanPostProcessor的processBeforeInitialization(),如果有关联的processor,则在Bean初始化之前都会执行这个实例的processBeforeInitialization()方法
- InitializingBean的afterPropertiesSet(),如果实现了该接口,则执行其afterPropertiesSet()方法
- Bean定义文件中定义init-method
- BeanPostProcessors的processAfterInitialization(),如果有关联的processor,则在Bean初始化之前都会执行这个实例的processAfterInitialization()方法
- DisposableBean的destroy(),在容器关闭时,如果Bean类实现了该接口,则执行它的destroy()方法
- Bean定义文件中定义destroy-method,在容器关闭时,可以在Bean定义文件中使用“destory-method”定义的方法
如果使用ApplicationContext来维护一个Bean的生命周期,则基本上与上边的流程相同,只不过在执行BeanNameAware的setBeanName()后,若有Bean类实现了org.springframework.context.ApplicationContextAware接口,则执行其setApplicationContext()方法,然后再进行BeanPostProcessors的processBeforeInitialization()
实际上,ApplicationContext除了向BeanFactory那样维护容器外,还提供了更加丰富的框架功能,如Bean的消息,事件处理机制等。
在这里一用仓颉的一幅图说明流程: 转载自 https://www.cnblogs.com/xrq730/p/6363055.html
以下是自己测试时打印的日志信息,可以看下加载顺序:
1 /** 2 * @ClassName: MySpringBean 3 * @Description: my spring bean to test 4 * @author: daniel.zhao 5 * @date: 2018年10月26日 上午10:12:37 6 */ 7 public class MySpringBean implements BeanNameAware, BeanFactoryAware, InitializingBean, ApplicationContextAware { 8 9 private ApplicationContext applicationContext; 10 11 private static final Logger logger = LoggerFactory.getLogger(MySpringBean.class); 12 13 public MySpringBean() { 14 logger.info("new MySpringBean......"); 15 } 16 17 @Override 18 public void setApplicationContext(ApplicationContext context) throws BeansException { 19 logger.info("ApplicationContextAware-setApplicationContext......"); 20 this.applicationContext = context; 21 } 22 23 @Override 24 public void afterPropertiesSet() throws Exception { 25 logger.info("InitializingBean-afterPropertiesSet......"); 26 } 27 28 @Override 29 public void setBeanFactory(BeanFactory bf) throws BeansException { 30 logger.info("BeanFactoryAware-setBeanFactory......"); 31 } 32 33 @Override 34 public void setBeanName(String name) { 35 logger.info("BeanNameAware-setBeanName......"); 36 } 37 38 public void init() { 39 logger.info("init-method......"); 40 } 41 }
/** * @ClassName: MySpringBeanPostProcessor * @author: daniel.zhao * @date: 2018年10月26日 上午10:40:21 */ @Component public class MySpringBeanPostProcessor implements BeanPostProcessor { private static final Logger logger = LoggerFactory.getLogger(MySpringBeanPostProcessor.class); @Override public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { if (bean instanceof MySpringBean) { logger.info("BeanPostProcessor-postProcessAfterInitialization......"); } return bean; } @Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { if (bean instanceof MySpringBean) { logger.info("BeanPostProcessor-postProcessBeforeInitialization......"); } return bean; } }
2018-10-26 10:49:48.768 INFO 5732 --- [ main] com.daniel.bean.MySpringBean : BeanNameAware-setBeanName......
2018-10-26 10:49:48.769 INFO 5732 --- [ main] com.daniel.bean.MySpringBean : BeanFactoryAware-setBeanFactory......
2018-10-26 10:49:48.769 INFO 5732 --- [ main] com.daniel.bean.MySpringBean : ApplicationContextAware-setApplicationContext......
2018-10-26 10:49:48.770 INFO 5732 --- [ main] c.daniel.bean.MySpringBeanPostProcessor : BeanPostProcessor-postProcessBeforeInitialization......
2018-10-26 10:49:48.770 INFO 5732 --- [ main] com.daniel.bean.MySpringBean : InitializingBean-afterPropertiesSet......
2018-10-26 10:49:48.770 INFO 5732 --- [ main] com.daniel.bean.MySpringBean : init-method......
2018-10-26 10:49:48.771 INFO 5732 --- [ main] c.daniel.bean.MySpringBeanPostProcessor : BeanPostProcessor-postProcessAfterInitialization......
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