java - 使用派生的 AbstractSingleBeanDefinitionParser 或其他方法在 BeanPostProcessor 中配置类

Question

我有一个实现 springs BeanPostProcessor 的类 A

public class A implements BeanPostProcessor {


   private B b;

   public A() {
      b = new B();
      b.set(...);          
   }


   public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
    return bean;
   }

   // Intercept all bean initialisations and return a proxy'd bean equipped with code
   // measurement capabilities
   public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
    return b.enhance(bean);
   }


}

我想配置我的类 b，它位于派生的 BeanPostProcessor 类 A 中。我如何使用 spring 配置(依赖注入(inject))这个类，这可能是因为它在 BeanPostProcessor 中......？

Answer 1

使用@Configuration 类

public static class Child {}

public static class Processor implements BeanPostProcessor {        
    @Autowired
    public Child child;             
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        return null; // Spring would complain if this was executed
    }
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        return null; // Spring would complain if this was executed
    }       
}

@Configuration
public static class Config {
    @Bean
    public static Processor processor() {
        return new Processor();
    }
    @Bean
    public Child child() {
        return new Child();
    }
}

public static void main(String[] args) throws IOException, ParseException, JAXBException, URISyntaxException, NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException, SQLException {     
    AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
    Processor processor = context.getBean(Processor.class);
    System.out.println(processor.child);
}

BeanPostProcessor 还不“存在”，因此它无法处理正在创建的其他 bean(这是 @Autowired 完成此 bean 所必需的)。 javadoc州

ApplicationContexts can autodetect BeanPostProcessor beans in their bean definitions and apply them to any beans subsequently created.

大胆的我。

使用 XML

<context:component-scan base-package="test"></context:component-scan>
<bean id="processor" class="test.Main.Processor"></bean>
<bean id="child" class="test.Main.Child"></bean>

ClassPathXmlApplicationContext xmlContext = new ClassPathXmlApplicationContext("context.xml");
processor = xmlContext.getBean(Processor.class);
System.out.println(processor.child);