Spring源码分析 (getBean过程详解) (十四)

Spring中有一个闭环:

getBean -> 创建依赖 -> getBean

过程:

1.createBeanInstance实例化 bean 2.populateBean属性注入 3.initializingBean初始化对象

createBeanInstance:getBean -> doGetBean -> createBean -> doCreateBean

initializingBean初始化对象: 1.激活Aware 2.后置处理器的应用 3.init方法

文章目录

• ​​1.过程一​​
• ​​2.过程二​​
• ​​3.过程三​​

1.过程一

InstantiationAwareBeanPostProcessor.postProcessBeforeInstantiation()

// 1, 初始化之前
    @Override
    public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
        System.out.println("MyInstantiationAwareBeanPostProcessor postProcessBeforeInstantiation");
        return null;
    }

判断是否创建了对象

SmartInstantiationAwareBeanPostProcessor.determineCandidateConstructors()

返回我们要使用的构造器候选列表, 默认使用无参构造器, 然后创建Bean实例, 使用BeanWrapper

@Override
    public Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName) throws BeansException {
        System.out.println("MySmartInstantiationAwareBeanPostProcessor determineCandidateConstructors");
        return null;
    }

2.过程二

BeanWrapper为装饰者模式。

MergedBeanDefinitionPostProcessor.postProcessMergedBeanDefinition()

合并bd信息, 再修改beanDefinition

// 合并bd信息, 再修改beanDefinition
    @Override
    public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
        System.out.println("MyMergedBeanDefinitionPostProcessor postProcessMergedBeanDefinition");
    }

InstantiationAwareBeanPostProcessor.postProcessAfterInstantiation()

初始化之后处理

@Override
    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
        System.out.println("MyInstantiationAwareBeanPostProcessor postProcessAfterInstantiation");
        return true;
    }

InstantiationAwareBeanPostProcessor.postProcessProperties()

处理属性值, 利用反射进行赋值

@Override
    public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) throws BeansException {
        System.out.println("MyInstantiationAwareBeanPostProcessor postProcessProperties");
        return null;
    }

这里的PropertyValues 为迭代器模式。去赋值

3.过程三

AbstractAutowireCapableBeanFactory.invokeAwareMethods()

激活Aware

BeanPostProcessor.postProcessBeforeInitialization()

进行初始化之前的增强处理, 改变之前创建Bean 的实例

@Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("MyBeanPostProcessor postProcessBeforeInitialization");
        return bean;
    }

InitializingBean.afterPropertiesSet()

@Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("MyInitializingBean afterPropertiesSet");
    }

BeanPostProcessor.postProcessAfterInitialization()

初始化之后的增强处理, 改变之前创建的Bean 实例

@Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("MyBeanPostProcessor postProcessAfterInitialization");
        return bean;
    }