spring源码（一）

学习的目的：

1. 深入理解spring的底层，设计思想
2. 学习spring这种设计思想，模式

Spring 中文文档： https://github.com/DocsHome/spring-docs/blob/master/pages/core/overview.md

sprig的核心
IOC
AOP

区分BeanFactory与ApplicationContext

BeanFactory 仅仅是创建bean
ApplicationContext集成了很多扩展点

扩展点：

1. BeanFactoryPostProcessor ```java @Component public class MyBeanPostProcessor implements BeanFactoryPostProcessor {

@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
    BeanDefinition beanName = beanFactory.getBeanDefinition("beanName");
    // 修改 bean的 bean Definition
}

}

2. BeanDefinitionRegistryPostProcessor
```java
public class MyBeanDefinitionRegistry implements BeanDefinitionRegistryPostProcessor {
    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        registry.registerBeanDefinition("bean",null;);
    }
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        beanFactory.addBeanPostProcessor(null);
    }
}

1. **BeanPostProcessor 比较重要
   前后9次用到
   通过该bean 扩展 完成aop，

**

public class MyBeanPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        return null;
    }
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        return null;
    }
}

getBean方法，比较重要

ApplicationContextAware

获取Context中的属性

IOC的大致流程