编辑“︁Spring容器扩展点”︁（章节）

== 主要扩展点 ==

=== 1. BeanPostProcessor ===
`BeanPostProcessor`接口允许在Spring容器实例化bean之后、初始化前后执行自定义逻辑。它是Spring容器中最常用的扩展点之一。

<syntaxhighlight lang="java">
public interface BeanPostProcessor {
    // 初始化前调用
    Object postProcessBeforeInitialization(Object bean, String beanName);
    
    // 初始化后调用
    Object postProcessAfterInitialization(Object bean, String beanName);
}
</syntaxhighlight>

'''示例：'''
<syntaxhighlight lang="java">
public class CustomBeanPostProcessor implements BeanPostProcessor {
    
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) {
        System.out.println("Before initialization: " + beanName);
        return bean; // 可以返回原始bean或包装后的bean
    }
    
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) {
        System.out.println("After initialization: " + beanName);
        return bean;
    }
}
</syntaxhighlight>

'''注册方式：'''
<syntaxhighlight lang="xml">
<bean class="com.example.CustomBeanPostProcessor"/>
</syntaxhighlight>

=== 2. BeanFactoryPostProcessor ===
`BeanFactoryPostProcessor`允许在容器加载完bean定义后、实例化bean前修改bean的定义（如修改属性值）。

<syntaxhighlight lang="java">
public interface BeanFactoryPostProcessor {
    void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory);
}
</syntaxhighlight>

'''示例：'''
<syntaxhighlight lang="java">
public class CustomBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
    
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
        BeanDefinition beanDef = beanFactory.getBeanDefinition("someBean");
        beanDef.getPropertyValues().add("propertyName", "newValue");
    }
}
</syntaxhighlight>

=== 3. ApplicationContextAware ===
通过实现`ApplicationContextAware`接口，bean可以获取对`ApplicationContext`的引用。

<syntaxhighlight lang="java">
public class AwareBean implements ApplicationContextAware {
    
    private ApplicationContext context;
    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
        this.context = applicationContext;
    }
    
    // 可以使用context获取其他bean等
}
</syntaxhighlight>

=== 4. 生命周期接口 ===
Spring提供了多个生命周期接口：
* `InitializingBean` - 定义初始化方法
* `DisposableBean` - 定义销毁方法

'''示例：'''
<syntaxhighlight lang="java">
public class LifecycleBean implements InitializingBean, DisposableBean {
    
    @Override
    public void afterPropertiesSet() {
        // 初始化逻辑
    }
    
    @Override
    public void destroy() {
        // 销毁逻辑
    }
}
</syntaxhighlight>