IOC初始化和互相引用解决

��羊 — Wed, 10 Nov 2010 08:27:00 GMT

摘要: 观察IOC中容器初始化某个Bean��序�Q�现先一个JAVABean�c�，看看控制台输出：package com.google.aop.exception.ioc; import org.springframework.beans.BeansException; import org.springframework.beans.factory.BeanFactory... 阅读全文

��羊 2010-11-10 16:27 发表评论

IOC监管Bean

��羊 — Wed, 03 Nov 2010 09:04:00 GMT

1.InitializingBean接口�Q�在初始化Bean时容器会调用前者的afterPropertiesSet()�Ҏ��

2.DisposableBean接口�Q�在析构Bean时容器会调用destroy()�Ҏ��

3.BeanFactoryAware接口�Q�当它被BeanFactory创徏后，它会拥有一个指向创建它的BeanFactory的引�?/font>

4.BeanPostProcessor接口�Q�这个接口两个方法，postProcessBeforeInitialization(Object bean, String beanName)和postProcessAfterInitialization(Object bean, String beanName) 在其他Bean构造前后执�?/p>

5.BeanFactoryPostProcessor接口�Q�Spring IoC容器允许BeanFactoryPostProcessor在容器实际实例化��M��其它的bean之前��d��配置元数据，�q�有可能修改�?/p>

package com.google.springioctest;

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.BeanFactory;

import org.springframework.beans.factory.BeanFactoryAware;

import org.springframework.beans.factory.DisposableBean;

import org.springframework.beans.factory.InitializingBean;

import org.springframework.beans.factory.config.BeanFactoryPostProcessor;

import org.springframework.beans.factory.config.BeanPostProcessor;

import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;

public class A implements BeanPostProcessor, InitializingBean,

BeanFactoryAware, BeanFactoryPostProcessor,DisposableBean {

public A() {

System.out.println("Class A");

}

private void init(){

System.out.println("Class A init");

}

@Override

public void afterPropertiesSet() throws Exception {

// TODO Auto-generated method stub

System.out.println("Class A afterPropertiesSet()");

}

@Override

public void destroy() throws Exception {

System.out.println("Class A destroy()");

}

@Override

public void setBeanFactory(BeanFactory beanFactory) throws BeansException {

// TODO Auto-generated method stub

System.out.println("Class A setBeanFactory()");

}

@Override

public Object postProcessAfterInitialization(Object bean, String beanName)

throws BeansException {

System.out.println("Class A postProcessAfterInitialization");

return null;

}

@Override

public Object postProcessBeforeInitialization(Object bean, String beanName)

throws BeansException {

// TODO Auto-generated method stub

System.out.println("Class A postProcessBeforeInitialization");

return null;

}

@Override

public void postProcessBeanFactory(

ConfigurableListableBeanFactory beanFactory) throws BeansException {

// TODO Auto-generated method stub

System.out.println("Class A postProcessBeanFactory");

}

执行�l�果�Q?/div>

Class A

Class A setBeanFactory()

Class A afterPropertiesSet()

Class A init

Class A postProcessBeanFactory

创徏一个B�c�，由A来监��B�c�，B实现 InitializingBean,BeanFactoryAware,BeanFactoryPostProcessor

package com.google.springioctest;

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.BeanFactory;

import org.springframework.beans.factory.BeanFactoryAware;

import org.springframework.beans.factory.DisposableBean;

import org.springframework.beans.factory.InitializingBean;

import org.springframework.beans.factory.config.BeanFactoryPostProcessor;

import org.springframework.beans.factory.config.BeanPostProcessor;

import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;

public class B implements InitializingBean, BeanFactoryAware,

BeanFactoryPostProcessor {

public B() {

System.out.println("Class B");

}

public void init() {

System.out.println("Class B init");

}

@Override

public void afterPropertiesSet() throws Exception {

System.out.println("Class B afterPropertiesSet");

}

@Override

public void setBeanFactory(BeanFactory beanFactory) throws BeansException {

System.out.println("Class B beanFactory");

}

@Override

public void postProcessBeanFactory(

ConfigurableListableBeanFactory beanFactory) throws BeansException {

// TODO Auto-generated method stub

System.out.println("Class B postProcessBeanFactory");

}

执行�l�果�Q?/div>

Class A

Class A setBeanFactory()

Class A afterPropertiesSet()

Class A init

Class B

Class B beanFactory

Class B afterPropertiesSet

Class B init

Class A postProcessBeanFactory

Class B postProcessBeanFactory

可以看出A�q�没有监��B�c�，也就是没调用BeanPostProcessor�q�个接口�?个方�?/div>

再来��L��B上的BeanFactoryPostProcessor接口

package com.google.springioctest;

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.BeanFactory;

import org.springframework.beans.factory.BeanFactoryAware;

import org.springframework.beans.factory.DisposableBean;

import org.springframework.beans.factory.InitializingBean;

import org.springframework.beans.factory.config.BeanFactoryPostProcessor;

import org.springframework.beans.factory.config.BeanPostProcessor;

import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;

public class B implements InitializingBean,

BeanFactoryAware{

public B() {

System.out.println("Class B");

}

public void init() {

System.out.println("Class B init");

}

@Override

public void afterPropertiesSet() throws Exception {

System.out.println("Class B afterPropertiesSet");

}

@Override

public void setBeanFactory(BeanFactory beanFactory) throws BeansException {

System.out.println("Class B beanFactory");

}

public void postProcessBeanFactory(

ConfigurableListableBeanFactory beanFactory) throws BeansException {

// TODO Auto-generated method stub

System.out.println("Class B postProcessBeanFactory");

}

执行输出�Q�Class A

Class A setBeanFactory()

Class A afterPropertiesSet()

Class A init

Class A postProcessBeanFactory

2010-11-3 21:33:31 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons

信息: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@8916a2: defining beans [A,B]; root of factory hierarchy

Class B

Class B beanFactory

Class A postProcessBeforeInitialization

2010-11-3 21:33:31 org.springframework.beans.factory.support.DefaultSingletonBeanRegistry destroySingletons

信息: Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@8916a2: defining beans [A,B]; root of factory hierarchy

Class A destroy()

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'B' defined in class path resource [icoContext.xml]: Invocation of init method failed; nested exception is java.lang.NullPointerException

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1338)

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:473)

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)

at java.security.AccessController.doPrivileged(Native Method)

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)

at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)

at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:429)

at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:728)

at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:380)

at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139)

at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:83)

at com.google.springioctest.Test.main(Test.java:8)

Caused by: java.lang.NullPointerException

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeCustomInitMethod(AbstractAutowireCapableBeanFactory.java:1393)

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1375)

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1335)

... 15 more

抛异�怺�。。。。�?/div>

原因是A�c�里的postProcessBeforeInitialization�Q�postProcessAfterInitialization2个方法没有返回bean,修改�?/div>

执行输出�Q?/div>

Class A

Class A setBeanFactory()

Class A afterPropertiesSet()

Class A init

Class A postProcessBeanFactory

2010-11-3 21:37:10 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons

信息: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1193779: defining beans [A,B]; root of factory hierarchy

Class B

Class B beanFactory

Class A postProcessBeforeInitialization

Class B afterPropertiesSet

Class B init

Class A postProcessAfterInitialization

在B�c�被初始化之后，也就是调用afterPropertiesSet之前那段旉��Q�属性初始化完成后，�q�行了回调，控制B�c?/div>

注意:在写被监控的Bean的时候，不能实现BeanFactoryPostProcessor�q�个接口,没看源码�Q�其实也不知道是什么原因，哈哈�Q�只能硬��C��

��羊 2010-11-03 17:04 发表评论

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IOC初始化和互相引用解决

IOC监管Bean