spring bean生命周期在bean初始化常用的三个接口 BeanPostProcessor，InstantiationAwareBeanPostProcessor和InitializingBea

本文链接：https://blog.youkuaiyun.com/m_ddNice/article/details/117564964

本文解析Spring框架中BeanPostProcessor和InitializingBean的作用，以及如何通过`@PostConstruct`和`@PreDestroy`注解控制初始化和销毁过程。实例代码和配置详解让你理解bean初始化的全过程。

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spring bean生命周期在bean初始化常用的三个接口 BeanPostProcessor，InstantiationAwareBeanPostProcessor和InitializingBean

BeanPostProcessor和InstantiationAwareBeanPostProcessor

   public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {

           System.out.println(beanName+"实例化之前");

       return null;
   }

    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {

            System.out.println(beanName+"实例化之后");

        return false;
    }

    public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeansException {
        return pvs;
    }

    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {

            System.out.println(beanName+"的后置处理器的Before");

        return bean;
    }

    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {

            System.out.println(beanName+"的后置处理器的After");

        return bean;
    }

带beanName 代表方法每个bean初始化都会执行

InitializingBean

@Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("我是初始化方法");
    }

只在该bean初始化时候执行

@PostConstruct 和 @PreDestroy 放在bean方法中，类似init方法

 @PostConstruct
    public void initMethod() {
        System.out.println("我是初始化方法");

    }

    @PreDestroy
    public void destory() {
        System.out.println("我是销毁方法");
    }

## 通过bean 定义配置

    @Configuration
    @ComponentScan(basePackages = "")
    public class MainConfig {

    @Bean(initMethod = "init")
    public Compent compent() {
        return new Compent();
    }
}