BeanPostProcessor使用

╰+哭是因爲堅強的太久メ 2022-11-20 03:56 119阅读 0赞

1. BeanPostProcessor简介

BeanPostProcessor是Spring IOC容器给我们提供的一个扩展接口。接口声明如下：

public interface BeanPostProcessor {
        //bean初始化方法调用前被调用
        Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;
        //bean初始化方法调用后被调用
        Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;
    }

**运行顺序**

===Spring IOC容器实例化Bean===  
===调用BeanPostProcessor的postProcessBeforeInitialization方法===  
===调用bean实例的初始化方法===  
===调用BeanPostProcessor的postProcessAfterInitialization方法===

![0ae3444bfbfde23a4d73f7ba942e86b6.png][]

image.png

2. BeanPostProcessor实例

/**
     * 后置处理器：初始化前后进行处理工作
     * 将后置处理器加入到容器中
     */
    @Component
    public class MyBeanPostProcessor implements BeanPostProcessor {
    
        @Override
        public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
            // TODO Auto-generated method stub
            System.out.println("postProcessBeforeInitialization..."+beanName+"=>"+bean);
            return bean;
        }
    
        @Override
        public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
            // TODO Auto-generated method stub
            System.out.println("postProcessAfterInitialization..."+beanName+"=>"+bean);
            return bean;
        }
    
    }

3. BeanFactoryPostProcessor简介

bean工厂的bean属性处理容器，说通俗一些就是可以管理我们的bean工厂内所有的beandefinition（未实例化）数据，可以随心所欲的修改属性。

4. BeanFactoryPostProcessor实例

@Component
    public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
    
        @Override
        public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
            System.out.println("MyBeanFactoryPostProcessor...postProcessBeanFactory...");
            int count = beanFactory.getBeanDefinitionCount();
            String[] names = beanFactory.getBeanDefinitionNames();
            System.out.println("当前BeanFactory中有"+count+" 个Bean");
            System.out.println(Arrays.asList(names));
        }
    
    }

**区别：**

注册BeanFactoryPostProcessor的实例，需要重载

void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException;

通过beanFactory可以获取bean的示例或定义等。同时可以修改bean的属性，这是和BeanPostProcessor最大的区别。

链接：https://www.jianshu.com/p/369a54201943

[0ae3444bfbfde23a4d73f7ba942e86b6.png]: /images/20221120/adb43b8cfe4d478496e5daa2f0f517d0.png