Bean的后置处理器

@Component
public class User {
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

@Component
public class UserService {
 
}

public class Peroson {
}

@ComponentScan("com.luban")
public class config {

}

 再没有Bean的后置处理器实现类之前

public class Main {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(config.class);

        UserService userService = applicationContext.getBean("userService", UserService.class);
        System.out.println(userService);

    }
}

输出;

@Component
public class LubanBeanPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        return null;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        return new Peroson();
    }
}

测试输出：

意思是userservice实际的类型的people ，但我们强行转成Userservice失败，因此报错，那为什么是people类型呢？

原因在于：

 上面箭头所指，实现了将Uservice类型的bean被替换成people类型的！！！

总结：

 实现类中这两个方法就是用来操作传过来的对象的，参数bean代表传过来的对象，也就是Userservice，beanName代表对象名

修改代码：

 @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (beanName.equals("userService")){
            System.out.println(beanName);
            System.out.println(bean);
        }
        return new Peroson();
    }

 输出：

修改代码：

 @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
     
            System.out.println(beanName);
            System.out.println(bean);
        
        return new Peroson();
    }

 输出：