# Spring IoC依赖来源

## 1. 依赖查找的来源

查找来源

![img](assets/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NvbmdoYW8wMDc=,size_16,color_FFFFFF,t_70#pic_center.png)

Spring 內建 BeanDefintion

![img](assets/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NvbmdoYW8wMDc=,size_16,color_FFFFFF,t_70#pic_center-16652818457652.png)

Spring 內建单例对象

![img](assets/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NvbmdoYW8wMDc=,size_16,color_FFFFFF,t_70#pic_center-16652818587724.png)

## 2. [依赖注入](https://so.csdn.net/so/search?q=依赖注入&spm=1001.2101.3001.7020)的来源

注入来源

![img](assets/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NvbmdoYW8wMDc=,size_16,color_FFFFFF,t_70#pic_center-16652818823628.png)

* 单例对象由 `org.springframework.beans.factory.config.SingletonBeanRegistry` 注册，`org.springframework.beans.factory.support.AbstractBeanFactory` 实现了这个接口，从容器中获取 Bean 的方法 `org.springframework.beans.factory.support.AbstractBeanFactory#doGetBean` 中，会先从单例对象中查找，如果查找到，直接返回；查找不到，则从 Spring BeanDefinition 中获取，并**执行生命周期函数**

## 3. Spring 容器管理和游离对象

* 依赖对象

![img](assets/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NvbmdoYW8wMDc=,size_16,color_FFFFFF,t_70#pic_center-166528190061910.png)

## 4. Spring BeanDefinition 作为依赖来源

  要素

* 元数据：BeanDefinition
* 注册：BeanDefinitionRegistry#registerBeanDefinition
* 类型：延迟和非延迟
* 顺序：Bean 生命周期顺序按照注册顺序

## 5、外部化配置作为依赖来源

![image-20221009171247256](assets/image-20221009171247256.png)

# 面试题

1、注入和查找的来源是否相同？

![image-20221009172428729](assets/image-20221009172428729.png)

2、单例对象能在IOC容器启动后注册码？

![image-20221009172505792](assets/image-20221009172505792.png)

3、spring依赖注入的来源有哪些？

![image-20221009172913945](assets/image-20221009172913945.png)