Spring中的那些钩子hook--InitializingBean和PostProcessor

InitializingBean

public class MyAware implements InitializingBean {
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("InitializingBean.afterPropertiesSet");
    }
}

在bean执行init-method之前执行的，设置完bean中的property后执行，使用这个方法我们可以初始化一些bean中的属性，一般情况下自定义注入的时候都会使用它

BeanPostProcessor

public class MyPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("4.MyService的BeanPostProcess.postProcessBeforeInitialization--"+beanName);
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("6.MyService的BeanPostProcess.postProcessAfterInitialization--"+beanName);
        return bean;
    }
}

postProcessBeforeInitialization在init-method方法执行之前，postProcessAfterInitialization在init-method方法之后

BeanFactoryPostProcessor

@Configuration
public class MyPostProcessor {
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        System.out.println("BeanFactoryPostProcessor的postProcessBeanFactory");
    }
}

在BeanFactory容器构建时触发

总结

在spring框架中PostProcessor这种类切面的接口使用的非常广泛，无论是在Bean初始化后修改属性值还是直接改变bean的实现类都可以让其足够的灵活