Spring學習筆記之bean生命週期

前言

上一篇文章主要學習了下bean的配置、注入、自定義屬性編輯器，今天來熟悉bean的生命週期。

任何一個事物都有自己的生命週期，生命的開始、生命中、生命結束。大家最熟悉的應該是servlet 的生命週期吧。和servlet 一樣spring bean 也有自己的生命週期。

在開發中生命週期是一個很常見的名詞，基本每種編程語言都能找到與它關聯的。關於bean的生命週期我在網上也找了好多，基本都差不多。這裡我主要是想通過代碼來驗證，畢竟學的知識都是一樣的，都是學的Java，最重要的是動手練習，這樣印象更深。

下面是它生命週期的描述，我們通過demo來進行驗證。

下圖是它執行的順序。

一、創建LiftCycle類實現BeanFactoryAware,BeanNameAware,InitializingBean,DisposableBean,ApplicationContextAware5個接口方法

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】調用<bean>的init-method屬性指定的初始化方法"); } public void myDestory() { System.out.println("【destroy-method】調用<bean>的destroy-method屬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、註冊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、註冊BeanPostProcessor接口

其實InstantiationAwareBeanPostProcessor繼承BeanPostProcessor，所以在上面我也實現了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、註冊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

這裡還是在上一個博客demo的基礎上進行修改，為了有其他干擾，我先把service去掉了。

 <?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsd"><bean id="beanPostProcessor"></bean><bean id="instantiationAwareBeanPostProcessor"></bean><bean id="beanFactoryPostProcessor"></bean><bean id="lifeCycle" init-method="myInit" destroy-method="myDestory"><property name="name" value="cuiyw1"></property></bean></beans>

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、輸入打印結果

可以發現輸出的順序和上面圖的順序基本一致。

總結

以上就是這篇文章的全部內容了，希望本文的內容對大家的學習或者工作具有一定的參考學習價值，如果有疑問大家可以留言交流，謝謝大家對武林網的支持。