protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) 扩展案例
时间: 2023-12-18 14:53:11 浏览: 34
假设我们有一个自定义注解 `@MyComponent`,我们想要在 Spring 加载 Bean 的时候自动扫描带有该注解的类,并将它们注册为 Bean。
首先,我们需要编写一个 BeanPostProcessor 实现类,用于扫描带有 `@MyComponent` 注解的类,然后将它们注册为 Bean。
```java
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;
@Component
public class MyComponentBeanPostProcessor implements BeanPostProcessor {
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if (bean.getClass().isAnnotationPresent(MyComponent.class)) {
((DefaultListableBeanFactory) beanFactory).registerSingleton(beanName, bean);
}
return bean;
}
}
```
然后,我们需要编写一个 BeanFactoryPostProcessor 实现类,用于在 BeanFactory 加载 Bean 定义之后调用 BeanPostProcessor,以实现自动注册 Bean 的逻辑。
```java
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.stereotype.Component;
@Component
public class MyComponentBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(false);
scanner.addIncludeFilter(new AnnotationTypeFilter(MyComponent.class));
for (BeanDefinition beanDefinition : scanner.findCandidateComponents("com.example")) {
((DefaultListableBeanFactory) beanFactory).registerBeanDefinition(beanDefinition.getBeanClassName(),
BeanDefinitionBuilder.genericBeanDefinition(beanDefinition.getBeanClassName()).getBeanDefinition());
}
}
}
```
最后,我们需要在配置类中将这两个类注册为 Bean。
```java
@Configuration
@ComponentScan(basePackages = "com.example")
public class AppConfig {
@Bean
public MyComponentBeanPostProcessor myComponentBeanPostProcessor() {
return new MyComponentBeanPostProcessor();
}
@Bean
public MyComponentBeanFactoryPostProcessor myComponentBeanFactoryPostProcessor() {
return new MyComponentBeanFactoryPostProcessor();
}
}
```
这样,在 Spring 加载 Bean 的时候,就会自动扫描带有 `@MyComponent` 注解的类,并将它们注册为 Bean。