java - Spring BeanPostProcessor 被调用了 3 次

Question

我正在执行 BeanPostProcessor 实现。我的 Bean 后处理器执行了 3 次。我在 init 方法之前额外调用了 2 次后处理器。我无法找到它发生的原因。请帮助我。

我的代码和配置文件如下

BeanPostProcessor 实现

public class BeanPP implements BeanPostProcessor{

    @Override
    public Object postProcessBeforeInitialization(Object o, String string) throws BeansException {
        System.out.println("---before initialization ------");
        return o;
        //throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public Object postProcessAfterInitialization(Object o, String string) throws BeansException {
        System.out.println("----After initializaion ---- ");
        return o;
        //To change body of generated methods, choose Tools | Templates.
    }        
}

客户 Bean

public class Customer {        
  private String name;

  public String getName() {
      System.out.println("..getName.....");
      return name;
  }

  public void setName(String name) {
      System.out.println("..setName.....");
      this.name = name;
  }

  @PostConstruct
  public void init(){
      System.out.println("....Bean is going though init method");
  }

  @PreDestroy
  public void destory(){
      System.out.println("....Bean is going to destroy.......");
  }
}

配置类

@Configuration
public class AppConfig {
    @Bean(name="customer")
    public Customer getCustomer(){
        return new Customer();
    }
    @Bean
    public BeanPP getPP(){
        return new BeanPP();
    }

}

主类

public class MainApp {

    public static void main(String[] args) {
        ApplicationContext appContext = new AnnotationConfigApplicationContext(AppConfig.class);
        Customer customer = (Customer)appContext.getBean("customer");
        customer.setName("test user ");
        System.out.println(".Name is .."+customer.getName());
    }
}

输出

---初始化之前----------初始化后-------初始化之前----------初始化后-------初始化之前------....Bean 正在通过 init 方法----初始化后----..设置名称.......getName......名字是..测试用户

Answer 1

Plain bean factories allow for programmatic registration of post-processors, applying to all beans created through this factory.

http://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/beans/factory/config/BeanPostProcessor.html

您已经定义了 3 个 bean，AppConfig、customer 和 PP。 bean 后处理器将在每次创建 bean 后执行。如果你有 3 个 bean，它将被执行 3 次。

@Configuration
public class AppConfig {
    @Bean(name="customer")
    public Customer getCustomer(){
        return new Customer();
    }
    @Bean
    public BeanPP getPP(){
        return new BeanPP();
    }
}

@Configuration也定义了一个bean，因为它继承自@Component。

http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/context/annotation/Configuration.html