浅谈Spring bean 生命周期验证

2019-11-26 11:05:11

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一、从源码注释看bean生命周期

从JDK源码上看，BeanFactory实现类需要支持Bean的完整生命周期，完整的初始化方法及其标准顺序（格式：接口方法）为:

1.BeanNameAware setBeanName 设置bean名称
2.BeanClassLoaderAware setBeanClassLoader 设置bean类加载器
3.BeanFactoryAware setBeanFactory 设置bean工厂
4.EnvironmentAware setEnvironment 设置环境：profiles+properties
5.EmbeddedValueResolverAware setEmbeddedValueResolver 设置嵌入式值解析器
6.ResourceLoaderAware setResourceLoader 设置资源载入器，只适用于在应用程序上下文中运行
7.ApplicationEventPublisherAware setApplicationEventPublisher注入应用事件发布器ApplicationEventPublisher
8.MessageSourceAware setMessageSource 设置国际化支持
9.ApplicationContextAware setApplicationContext 设置应用上下文
10.ServletContextAware setServletContext 设置servlet上下文
11.BeanPostProcessors postProcessBeforeInitialization 执行bean处理器前置方法
12.InitializingBean afterPropertiesSet 执行初始化Bean设置完属性后置方法
13.a custom init-method definition 执行自定义初始化方法
14.BeanPostProcessors postProcessAfterInitialization 执行bean处理器后置方法

销毁顺序：

1.DestructionAwareBeanPostProcessors postProcessBeforeDestruction 销毁处理器的前置方法
2.DisposableBean destroy Bean销毁回调方法
3.a custom destroy-method definition 用户自定义销毁方法

核心方法流程图：

二、测试验证

2.1分析原理

前面说的17个步骤都可以测试，我们选取其中的8个步骤进行测试如下：

初始化流程：

1.BeanNameAware setBeanName 设置bean名称
3.BeanFactoryAware setBeanFactory 设置bean工厂
11.BeanPostProcessors postProcessBeforeInitialization 执行bean处理器前置方法
12.InitializingBean afterPropertiesSet 执行初始化Bean设置完属性后置方法
13.a custom init-method definition 执行自定义初始化方法
14.BeanPostProcessors postProcessAfterInitialization 执行bean处理器后置方法

销毁流程：

2.DisposableBean destroy Bean销毁回调方法
3.a custom destroy-method definition 用户自定义销毁方法

2.2 代码清单

1.构建一个Person类，实现BeanFactoryAware, BeanNameAware, InitializingBean, DisposableBean接口。

package spring.ioc;import org.springframework.beans.BeansException;import org.springframework.beans.factory.BeanFactory;import org.springframework.beans.factory.BeanFactoryAware;import org.springframework.beans.factory.BeanNameAware;import org.springframework.beans.factory.DisposableBean;import org.springframework.beans.factory.InitializingBean;public class Person implements BeanFactoryAware, BeanNameAware, InitializingBean, DisposableBean {    private String name;    private String mobile;     public Person() {    super();    System.out.println("[构造器] 调用Person的构造器实例化");  }  public String getName() {    return name;  }  public void setName(String name) {    System.out.println("[属性注入] name="+name);    this.name = name;  }  public String getMobile() {    return mobile;  }  public void setMobile(String mobile) {    System.out.println("[属性注入] mobile="+mobile);    this.mobile = mobile;  }  @Override  public void destroy() throws Exception {    System.out.println("[接口DisposableBean.destroy() ]");  }  @Override  public void afterPropertiesSet() throws Exception {    System.out.println("[接口InitializingBean.afterPropertiesSet() ]");  }  @Override  public void setBeanName(String name) {    System.out.println("[接口BeanNameAware.setBeanName() ]");  }  @Override  public void setBeanFactory(BeanFactory beanFactory) throws BeansException {    System.out.println("[接口BeanFactoryAware.setBeanFactory() ]");  }  public void myInit(){    System.out.println("[init-method]调用<bean>的init-method属性指定的初始化方法");  }    public void myDestory() {    System.out.println("[destroy-method]调用<bean>的destroy-method属性指定的销毁方法");  }}

2.自定义工厂后处理器，复写postProcessBeanFactory方法，获取bean定义后添加属性mobile=110

package spring.ioc;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.BeanDefinition;import org.springframework.beans.factory.config.BeanFactoryPostProcessor;import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;/** *  * @ClassName:MyBeanFactoryPostProcessor * @Description:自定义工厂后处理器 * @author diandian.zhang * @date 2017年10月25日下午7:14:09 */public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {  public MyBeanFactoryPostProcessor() {    super();    System.out.println("[MyBeanFactoryPostProcessor工厂后处理器]BeanFactoryPostProcessor实现类构造器！！");  }  @Override  public void postProcessBeanFactory(ConfigurableListableBeanFactory arg0)      throws BeansException {    System.out.println("[MyBeanFactoryPostProcessor工厂后处理器]BeanFactoryPostProcessor.postProcessBeanFactory()获取bean定义后添加属性mobile=110");    BeanDefinition bd = arg0.getBeanDefinition("person");    bd.getPropertyValues().addPropertyValue("mobile", "110");  }}

3.自定义Bean后处理器，复写postProcessBeforeInitialization和postProcessAfterInitialization2个方法，分别对应初始化前后时的操作。

package spring.ioc;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.BeanPostProcessor;/** *  * @ClassName:MyBeanPostProcessor * @Description:自定义Bean后处理器 * @author diandian.zhang * @date 2017年10月25日下午7:03:53 */public class MyBeanPostProcessor implements BeanPostProcessor {  public MyBeanPostProcessor() {    super();    System.out.println("这是BeanPostProcessor实现类构造器！！");  }  /**   *    * @Description 初始化前，处理器   * @param bean   * @param beanName   * @return   * @throws BeansException   * @author diandian.zhang   * @date 2017年10月25日下午7:07:02   * @see org.springframework.beans.factory.config.BeanPostProcessor#postProcessBeforeInitialization(java.lang.Object, java.lang.String)   */  @Override  public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {    System.out.println("BeanPostProcessor接口方法postProcessBeforeInitialization对属性进行更改！beanName="+beanName);    return bean;  }    /**   *    * @Description 初始化后，处理器   * @param bean   * @param beanName   * @return   * @throws BeansException   * @author diandian.zhang   * @date 2017年10月25日下午7:07:07   * @see org.springframework.beans.factory.config.BeanPostProcessor#postProcessAfterInitialization(java.lang.Object, java.lang.String)   */  @Override  public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {    System.out.println("BeanPostProcessor接口方法postProcessAfterInitialization对属性进行更改！beanName="+beanName);    return bean;//注意，如果返回null,后续BeanPostProcessor不会再执行  }  }

4.自定义实例化bean后处理器适配器，复写postProcessBeforeInstantiation、postProcessBeforeInstantiation、postProcessPropertyValues分别对应实例化Bean前调用、实例化Bean后调用、设置某个属性时调用

注意：InstantiationAwareBeanPostProcessorAdapter ，这里是实例化Instantiation，不是初始化Initialization！！！

package spring.ioc;import java.beans.PropertyDescriptor;import org.springframework.beans.BeansException;import org.springframework.beans.PropertyValues;import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;/** *  * @ClassName:MyInstantiationAwareBeanPostProcessor * @Description:BeanPostProcessor的子类，增加了更多自定方法 * @author diandian.zhang * @date 2017年10月25日下午7:09:15 */public class MyInstantiationAwareBeanPostProcessor extends    InstantiationAwareBeanPostProcessorAdapter {  public MyInstantiationAwareBeanPostProcessor() {    super();    System.out.println("这是InstantiationAwareBeanPostProcessorAdapter实现类构造器！！");  }  // 接口方法、实例化Bean之前调用  @Override  public Object postProcessBeforeInstantiation(Class<?> beanClass,String beanName) throws BeansException {    System.out.println("InstantiationAwareBeanPostProcessor调用postProcessBeforeInstantiation方法[实例化Bean之前调用 ]beanname="+beanName);    return null;  }  // 接口方法、实例化Bean之后调用  @Override  public Object postProcessAfterInitialization(Object bean, String beanName)      throws BeansException {    System.out .println("InstantiationAwareBeanPostProcessor调用postProcessAfterInitialization方法[实例化Bean之后调用]beanname="+beanName);    return bean;  }  // 接口方法、设置某个属性时调用  @Override  public PropertyValues postProcessPropertyValues(PropertyValues pvs,      PropertyDescriptor[] pds, Object bean, String beanName)      throws BeansException {    System.out.println("InstantiationAwareBeanPostProcessor调用postProcessPropertyValues方法 pvs="+pvs+",beanName="+beanName);    return pvs;  }}

5.测试类，使用ClassPathXmlApplicationContext从xml中读取bean配置文件生成applicationContext容器应用上下文，这一步对应容器初始化。第二部从应用上下文中获取bean。最后一步注册一个关闭钩子，在容器关闭时触发。

package spring.ioc;import org.junit.Test; 6 import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;10 import spring.aop.xml.dao.Dao;/** *  * @ClassName:IOCTest * @Description:测试类 * @author diandian.zhang * @date 2017年10月25日下午4:42:01 */public class IOCTest {    @Test  public void iocPersonTest(){    System.out.println("=============容器初始化======start=========");    @SuppressWarnings("resource")    ApplicationContext applicationContext = new ClassPathXmlApplicationContext("simple_spring_bean.xml");//源码入口    System.out.println("=============容器初始化=======end========");    System.out.println("=============获取person bean====start=======");    Person person = applicationContext.getBean("person",Person.class);//获取Bean    System.out.println("=============获取person bean====end=======,person类名="+person.getClass().getName());    System.out.println("=============注册关闭钩子，关闭容器（JVM shutdown）时触发钩子！================");    ((ClassPathXmlApplicationContext)applicationContext).registerShutdownHook();  }}

直接运行，结果如下：

=============容器初始化======start=========log4j:WARN No appenders could be found for logger (org.springframework.core.env.StandardEnvironment).log4j:WARN Please initialize the log4j system properly.[MyBeanFactoryPostProcessor工厂后处理器]BeanFactoryPostProcessor实现类构造器！！[MyBeanFactoryPostProcessor工厂后处理器]BeanFactoryPostProcessor.postProcessBeanFactory()获取bean定义后添加属性mobile=110这是BeanPostProcessor实现类构造器！！这是InstantiationAwareBeanPostProcessorAdapter实现类构造器！！InstantiationAwareBeanPostProcessor调用postProcessBeforeInstantiation方法[实例化Bean之前调用 ]beanname=person[构造器] 调用Person的构造器实例化InstantiationAwareBeanPostProcessor调用postProcessPropertyValues方法 pvs=PropertyValues: length=2; bean property 'mobile'; bean property 'name',beanName=person[属性注入] mobile=110[属性注入] name=张三[接口BeanNameAware.setBeanName() ][接口BeanFactoryAware.setBeanFactory() ]BeanPostProcessor接口方法postProcessBeforeInitialization对属性进行更改！beanName=person[接口InitializingBean.afterPropertiesSet() ][init-method]调用<bean>的init-method属性指定的初始化方法BeanPostProcessor接口方法postProcessAfterInitialization对属性进行更改！beanName=personInstantiationAwareBeanPostProcessor调用postProcessAfterInitialization方法[实例化Bean之后调用]beanname=person=============容器初始化=======end=====================获取person bean====start====================获取person bean====end=======,person类名=spring.ioc.Person=============注册关闭钩子，关闭容器（JVM shutdown）时触发钩子！================[接口DisposableBean.destroy() ][destroy-method]调用<bean>的destroy-method属性指定的销毁方法

总结流程：