springbean的加载过程及应用场景分析

@Component
public class MyBeanPostProcessor implements InstantiationAwareBeanPostProcessor, DestructionAwareBeanPostProcessor {
    private static final Logger log = LoggerFactory.getLogger(MyBeanPostProcessor.class);
    // 实例化之前
    @Override
    public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
        if (beanName.equals("lifeCycleBean")) {
            log.info("初始化之前执行, 这里返回的bean会替换原版本的bean");
        }
        return null;
    }
    // 实例化之后
    @Override
    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
        if (beanName.equals("lifeCycleBean")) {
            log.info("实例化之后执行, 这里返回false会跳过依赖注入阶段");
            //return false;
        }
        return true;
    }
    // 依赖注入阶段执行
    @Override
    public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) throws BeansException {
        if(beanName.equals("lifeCycleBean")){
            log.info("依赖注入阶段执行, 如@Autowired, @Value, @Resource");
        }
        return pvs;
    }
    // 初始化之前
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if(beanName.equals("lifeCycleBean")){
            log.info("初始化之前执行, 这里返回的对象会替换原本的bean, 如@PostConstruct, @ConfigurationProperties");
        }
        return bean;
    }
    // 初始化之后执行
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (beanName.equals("lifeCycleBean")) {
            log.info("初始化之后执行, 这里返回的对象会替换原本的bean, 如代理增强");
        }
        return bean;
    }
    // 销毁之前
    @Override
    public void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException {
        if(beanName.equals("lifeCycleBean")){
            log.info("销毁之前执行, 如 @PreDestroy");
        }
    }
}