Spring bean生命周期知识点讲解

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前言

任何一个事物都有自己的生命周期，生命的开始、生命中、生命结束。大家最熟悉的应该是servlet 的生命周期吧。和 servlet 一样 spring bean 也有自己的生命周期。

在开发中生命周期是一个很常见的名词，基本每种编程语言都能找到与它关联的。关于bean的生命周期我在网上也找了好多，基本都差不多。这里我主要是想通过代码来验证，毕竟学的知识都是一样的，都是学的Java，最重要的是动手练习，这样印象更深。

下面是它生命周期的描述，我们通过demo来进行验证。

下图是它执行的顺序。

一、创建LiftCycle类实现BeanFactoryAware,BeanNameAware,InitializingBean,DisposableBean,ApplicationContextAware5个接口方法

package Cuiyw.Spring.Service;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;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;public class LifeCycle implements BeanFactoryAware,BeanNameAware,InitializingBean,DisposableBean,ApplicationContextAware{  private String name; public String getName() { System.out.println("getName name="+name); return name; } public void setName(String name) {  System.out.println("setName name="+name); this.name = name; } public void afterPropertiesSet() throws Exception { // TODO Auto-generated method stub  System.out.println("InitializingBean.afterPropertiesSet()"); } public void setBeanName(String arg0) { // TODO Auto-generated method stub System.out.println("BeanNameAware.setBeanName"); } public void setBeanFactory(BeanFactory arg0) throws BeansException { // TODO Auto-generated method stub System.out.println("BeanFactoryAware.setBeanFactory"); } public void destroy() throws Exception { // TODO Auto-generated method stub System.out.println("DisposableBean.destroy"); } public void myInit() { System.out.println("【init-method】调用的init-method属性指定的初始化方法"); } public void myDestory() { System.out.println("【destroy-method】调用的destroy-method属性指定的初始化方法"); } public void setApplicationContext(ApplicationContext arg0) throws BeansException { // TODO Auto-generated method stub  System.out.println("ApplicationContextAware.setApplicationContext"); } }

二、注册InstantiationAwareBeanPostProcessor接口

package Cuiyw.Spring.Service;import java.beans.PropertyDescriptor;import org.springframework.beans.BeansException;import org.springframework.beans.PropertyValues;import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessor;public class MyInstantiationAwareBeanPostProcessor implements InstantiationAwareBeanPostProcessor{ public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { // TODO Auto-generated method stub System.out.println("InstantiationAwareBeanPostProcessor.postProcessAfterInitialization"); return bean; } public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { // TODO Auto-generated method stub System.out.println("InstantiationAwareBeanPostProcessor.postProcessBeforeInitialization"); return bean; } public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException { // TODO Auto-generated method stub System.out.println("InstantiationAwareBeanPostProcessor.postProcessAfterInstantiation"); return true; } public Object postProcessBeforeInstantiation(Class beanClass, String beanName) throws BeansException { // TODO Auto-generated method stub System.out.println("InstantiationAwareBeanPostProcessor.postProcessBeforeInstantiation"); return null; } public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean,  String beanName) throws BeansException { // TODO Auto-generated method stub System.out.println("InstantiationAwareBeanPostProcessor.postProcessPropertyValues"); return pvs; }}

三、注册BeanPostProcessor接口

其实InstantiationAwareBeanPostProcessor继承BeanPostProcessor，所以在上面我也实现了BeanPostProcessor接口的方法

package Cuiyw.Spring.Service;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.BeanPostProcessor;public class MyBeanPostProcessor implements BeanPostProcessor { public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { // TODO Auto-generated method stub System.out.println("BeanPostProcessor.postProcessAfterInitialization "); return bean; } public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { // TODO Auto-generated method stub System.out.println("BeanPostProcessor.postProcessBeforeInitialization"); return bean; }}

四、注册BeanFactoryPostProcessor接口

package Cuiyw.Spring.Service;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.BeanFactoryPostProcessor;import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor { public void postProcessBeanFactory(ConfigurableListableBeanFactory arg0) throws BeansException { // TODO Auto-generated method stub System.out.println("BeanFactoryPostProcessor.postProcessBeanFactory"); }}

五、在上下文中配置

这里还是在上一个博客demo的基础上进行修改，为了有其他干扰，我先把service去掉了。

六、在main中使用bean

package Cuiyw.SpringAop;import org.springframework.beans.factory.BeanFactory;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import Cuiyw.Spring.IService.IService;import Cuiyw.Spring.Service.LifeCycle;public class App { public static void main( String[] args ) { ApplicationContext context=new ClassPathXmlApplicationContext(new String[]{"ApplicationContext.xml"}); BeanFactory factory=context; LifeCycle lifeCycle=factory.getBean("lifeCycle",LifeCycle.class); lifeCycle.setName("cuiyw2");  System.out.println("lifeCycle.name="+lifeCycle.getName()); ((ClassPathXmlApplicationContext)factory).registerShutdownHook();  /*service=(IService)factory.getBean("ServiceA"); service.service("Cuiyw ServiceA");  service=(IService)factory.getBean("ServiceImpl"); service.service("Cuiyw ServiceImpl"); */ }}

七、输入打印结果

可以发现输出的顺序和上面图的顺序基本一致。

感谢各位的阅读，以上就是"Spring bean生命周期知识点讲解"的内容了，经过本文的学习后，相信大家对Spring bean生命周期知识点讲解这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是，小编将为大家推送更多相关知识点的文章，欢迎关注！