调用了3次Spring BeanPostProcessor

Question

我的代码和配置文件如下

BeanPostProcesssor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.......");
  }
}

@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

---在初始化之前-----在初始化之后----在初始化之前----在初始化之前----在初始化之前----在初始化之前----...bean通过init方法----在初始化之后----...setname.......GetName.....名称为..测试用户

Answer 1

普通bean工厂允许对后处理器进行编程注册，应用于通过该工厂创建的所有bean。

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 post处理器将在每次bean创建后执行。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();
    }
}