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158
src/content/posts/Java/Spring/SpringBean生命周期.md
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158
src/content/posts/Java/Spring/SpringBean生命周期.md
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---
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title: SpringBean生命周期
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published: 2025-07-28
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description: ''
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image: ''
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tags: ["Spring","Java"]
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category: 'Java > Spring'
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draft: false
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lang: ''
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---
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# Bean 的生命周期
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Bean生命周期可以粗略的划分为五大步：
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第一步：实例化Bean
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第二步：Bean属性赋值
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第三步：初始化Bean
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第四步：使用Bean
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第五步：销毁Bean
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```java
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package com.powercode.spring6.beans;
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public class User {
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private String name;
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public User() {
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System.out.println("1.实例化Bean");
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}
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public void setName(String name) {
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this.name = name;
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System.out.println("2.Bean属性赋值");
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}
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public void initBean(){
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System.out.println("3.初始化Bean");
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}
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public void destroyBean(){
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System.out.println("5.销毁Bean");
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}
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}
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```
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```
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2024-01-11 12:21:23 618 [main] DEBUG org.springframework.context.support.ClassPathXmlApplicationContext - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@183e8023
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2024-01-11 12:21:23 715 [main] DEBUG org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loaded 1 bean definitions from class path resource [spring12.xml]
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2024-01-11 12:21:23 732 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'userBean'
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1.实例化Bean
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2.Bean属性赋值
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3.初始化Bean
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4.使用Bean
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2024-01-11 12:21:23 774 [main] DEBUG org.springframework.context.support.ClassPathXmlApplicationContext - Closing org.springframework.context.support.ClassPathXmlApplicationContext@183e8023, started on Thu Jan 11 12:21:23 CST 2024
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5.销毁Bean
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2024-01-11 12:21:23 774 [main] DEBUG org.springframework.beans.factory.support.DisposableBeanAdapter - Custom destroy method 'destroyBean' on bean with name 'userBean' completed
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进程已结束，退出代码为 0
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```
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## Bean后处理器
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加上后处理器就变成七步了：
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### BeanPostProcessor 的核心作用
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BeanPostProcessor 本身并不属于某个特定 Bean 的生命周期，而是作用于容器中所有 Bean 的 “全局处理器”。它的核心功能是：在 Bean 完成实例化和属性赋值后、初始化方法（如 afterPropertiesSet() 或 init-method）执行前后，对 Bean 进行加工或增强。
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上图中检查Bean是否实现了Aware的相关接口是什么意思？
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## Aware相关接口
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Aware相关的接口包括：BeanNameAware、BeanClassLoaderAware、BeanFactoryAware
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当Bean实现了BeanNameAware，Spring会将Bean的名字传递给Bean。
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当Bean实现了BeanClassLoaderAware，Spring会将加载该Bean的类加载器传递给Bean。
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当Bean实现了BeanFactoryAware，Spring会将Bean工厂对象传递给Bean。
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测试以上10步，可以让User类实现5个接口，并实现所有方法：
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- BeanNameAware
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- BeanClassLoaderAware
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- BeanFactoryAware
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- InitializingBean
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- DisposableBean
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## InitializingBean 的核心作用
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当一个 Bean 实现了 InitializingBean 接口后，Spring 容器会在该 Bean 的所有属性都被成功设置（即完成属性注入）之后，自动调用其 afterPropertiesSet() 方法。这一特性使得开发者可以在 Bean 正式投入使用前，进行一些必要的初始化操作，例如数据校验、资源加载、状态初始化等。
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## DisposableBean核心作用
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DisposableBean 是 Spring 提供的销毁回调接口，其核心作用是在 Bean 即将被容器销毁前，触发自定义的清理操作。
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```java
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package com.powercode.spring6.beans;
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import org.springframework.beans.BeansException;
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import org.springframework.beans.factory.*;
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/**
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* @author 动力节点
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* @version 1.0
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* @className User
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* @since 1.0
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**/
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public class User implements BeanNameAware, BeanClassLoaderAware, BeanFactoryAware, InitializingBean, DisposableBean {
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private String name;
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public User() {
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System.out.println("1.实例化Bean");
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}
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public void setName(String name) {
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this.name = name;
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System.out.println("2.Bean属性赋值");
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}
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public void initBean(){
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System.out.println("6.初始化Bean");
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}
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public void destroyBean(){
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System.out.println("10.销毁Bean");
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}
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@Override
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public void setBeanClassLoader(ClassLoader classLoader) {
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System.out.println("3.类加载器：" + classLoader);
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}
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@Override
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public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
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System.out.println("3.Bean工厂：" + beanFactory);
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}
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@Override
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public void setBeanName(String name) {
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System.out.println("3.bean名字：" + name);
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}
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@Override
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public void destroy() throws Exception {
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System.out.println("9.DisposableBean destroy");
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}
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@Override
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public void afterPropertiesSet() throws Exception {
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System.out.println("5.afterPropertiesSet执行");
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}
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}
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```
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172
src/content/posts/Java/Spring/Spring常见面试题.md
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172
src/content/posts/Java/Spring/Spring常见面试题.md
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@@ -0,0 +1,172 @@
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---
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title: Spring常见面试题
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published: 2025-07-28
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description: ''
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image: ''
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tags: ["Spring","Java"]
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category: 'Java > Spring'
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draft: false
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lang: ''
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---
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# @Autowired 和 @Resource 的区别是什么？
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@Autowired属于Spring内置的注解，默认的注入方式是byType，也就是根据类型匹配，当有多个实现时
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byType就没办法正确注入了，这个时候可以结合@Qualifier注解一起使用，指定注入的名称。当然也可以使用byName，也就是根据名称注入，但是需要结合@Qualifier注解一起使用。
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@Resource 是Java自带注解，属于J2EE的，默认注入方式是byName，也就是根据名称注入，当找不到与名称匹配的bean时，根据类型注入。当然也可以结合@Qualifier注解一起使用，指定注入的名称。
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@Resource 有两个比较重要且日常开发常用的属性：name（名称）、type（类型）。
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如果仅指定 name 属性则注入方式为byName，如果仅指定type属性则注入方式为byType，如果同时指定name 和type属性（不建议这么做）则注入方式为byType+byName。
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@Autowired 支持在构造函数、方法、字段和参数上使用。
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@Resource 主要用于字段和方法上的注入，不支持在构造函数或参数上使用。
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# Bean 的生命周期
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Bean生命周期可以粗略的划分为五大步：
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第一步：实例化Bean
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第二步：Bean属性赋值
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第三步：初始化Bean
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第四步：使用Bean
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第五步：销毁Bean
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```java
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package com.powercode.spring6.beans;
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public class User {
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private String name;
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public User() {
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System.out.println("1.实例化Bean");
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}
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public void setName(String name) {
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this.name = name;
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System.out.println("2.Bean属性赋值");
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}
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public void initBean(){
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System.out.println("3.初始化Bean");
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}
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public void destroyBean(){
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System.out.println("5.销毁Bean");
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}
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}
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```
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```
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2024-01-11 12:21:23 618 [main] DEBUG org.springframework.context.support.ClassPathXmlApplicationContext - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@183e8023
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2024-01-11 12:21:23 715 [main] DEBUG org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loaded 1 bean definitions from class path resource [spring12.xml]
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2024-01-11 12:21:23 732 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'userBean'
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1.实例化Bean
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2.Bean属性赋值
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3.初始化Bean
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4.使用Bean
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2024-01-11 12:21:23 774 [main] DEBUG org.springframework.context.support.ClassPathXmlApplicationContext - Closing org.springframework.context.support.ClassPathXmlApplicationContext@183e8023, started on Thu Jan 11 12:21:23 CST 2024
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5.销毁Bean
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2024-01-11 12:21:23 774 [main] DEBUG org.springframework.beans.factory.support.DisposableBeanAdapter - Custom destroy method 'destroyBean' on bean with name 'userBean' completed
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进程已结束，退出代码为 0
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```
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## Bean后处理器
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加上后处理器就变成七步了：
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### BeanPostProcessor 的核心作用
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BeanPostProcessor 本身并不属于某个特定 Bean 的生命周期，而是作用于容器中所有 Bean 的 “全局处理器”。它的核心功能是：在 Bean 完成实例化和属性赋值后、初始化方法（如 afterPropertiesSet() 或 init-method）执行前后，对 Bean 进行加工或增强。
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上图中检查Bean是否实现了Aware的相关接口是什么意思？
|
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|
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## Aware相关接口
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Aware相关的接口包括：BeanNameAware、BeanClassLoaderAware、BeanFactoryAware
|
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|
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当Bean实现了BeanNameAware，Spring会将Bean的名字传递给Bean。
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当Bean实现了BeanClassLoaderAware，Spring会将加载该Bean的类加载器传递给Bean。
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当Bean实现了BeanFactoryAware，Spring会将Bean工厂对象传递给Bean。
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测试以上10步，可以让User类实现5个接口，并实现所有方法：
|
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- BeanNameAware
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- BeanClassLoaderAware
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- BeanFactoryAware
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- InitializingBean
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- DisposableBean
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## InitializingBean 的核心作用
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当一个 Bean 实现了 InitializingBean 接口后，Spring 容器会在该 Bean 的所有属性都被成功设置（即完成属性注入）之后，自动调用其 afterPropertiesSet() 方法。这一特性使得开发者可以在 Bean 正式投入使用前，进行一些必要的初始化操作，例如数据校验、资源加载、状态初始化等。
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## DisposableBean核心作用
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DisposableBean 是 Spring 提供的销毁回调接口，其核心作用是在 Bean 即将被容器销毁前，触发自定义的清理操作。
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|
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```java
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package com.powercode.spring6.beans;
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import org.springframework.beans.BeansException;
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import org.springframework.beans.factory.*;
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/**
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* @author 动力节点
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* @version 1.0
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* @className User
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* @since 1.0
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**/
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public class User implements BeanNameAware, BeanClassLoaderAware, BeanFactoryAware, InitializingBean, DisposableBean {
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private String name;
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public User() {
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System.out.println("1.实例化Bean");
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}
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public void setName(String name) {
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this.name = name;
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System.out.println("2.Bean属性赋值");
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}
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public void initBean(){
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System.out.println("6.初始化Bean");
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}
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public void destroyBean(){
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System.out.println("10.销毁Bean");
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}
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@Override
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public void setBeanClassLoader(ClassLoader classLoader) {
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System.out.println("3.类加载器：" + classLoader);
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}
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@Override
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public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
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System.out.println("3.Bean工厂：" + beanFactory);
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}
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@Override
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public void setBeanName(String name) {
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System.out.println("3.bean名字：" + name);
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}
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@Override
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public void destroy() throws Exception {
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System.out.println("9.DisposableBean destroy");
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}
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@Override
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public void afterPropertiesSet() throws Exception {
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System.out.println("5.afterPropertiesSet执行");
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}
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}
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```
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Reference in New Issue
Block a user