BeanFactoryPostProcessor的使用

BeanFactoryPostProcessor插手spring bean工厂对bean的定义
1、通过实现BeanFactoryPostProcessor接口，重写postProcessBeanFactory方法，可以获取到类的BeanDefinition对象，通过BeanDefinition对象插手bean的定义。（实现类要交给spring管理才可以生效）
例：将IndexDao对象从singleton改为prototype

@Component
public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        BeanDefinition indexDao = beanFactory.getBeanDefinition("indexDao");
        indexDao.setScope("prototype");
    }
}

@Component
public class IndexDao implements Dao {
    @Override
    public void query(){
        System.out.println("index");
    }
}

public class Test {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext app = new AnnotationConfigApplicationContext();
        app.register(Appconfig.class);
        app.refresh();
        Dao bean = app.getBean(IndexDao.class);
        Dao bean1 = app.getBean(IndexDao.class);
        System.out.println(bean.hashCode()+"--"+bean1.hashCode());
    }
}
执行结果：