【Spring】- Bean生命周期

ゝ一世哀愁。 2022-10-02 09:51 240阅读 0赞

[2019独角兽企业重金招聘Python工程师标准>>> ][2019_Python_] ![hot3.png][]

## Spring Bean的生命周期： ##

1.  bean对象实例化
2.  属性注入
3.  beanfactory
4.  ApplicationContext
5.  postProcessBeforeInitialization
6.  InitializingBean
7.  postProcessAfterInitialization
8.  DisposableBean(销毁Bean)

Bean生命周期相关接口介绍：

*  BeanNameAware: Bean可获取在BeanFactory中的名称
 *  BeanFactoryAware：Bean可获取所在的BeanFactory对象
 *  ApplicationContextAware：可获取Bean所在的ApplicationContext
 *  InitializingBean:Bean属性设置完成后的自定义操作接口：例如设置自定义的初始化方法init-method
 *  DisposableBean：销毁Bean的相关资源

--------------------

**Spring配置文件**： 配置简单的Bean和1个Bean后置处理器，并且设置自定义的初始化方法：init-method="defineInitMethod"

**Bean对象**,实现相关生命周期接口：

package com.zhiwei.lifecycle;
    
    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 ConcreteBean implements BeanNameAware,BeanFactoryAware,
    ApplicationContextAware,InitializingBean,DisposableBean{
    
    	private String name;
    	
    	public ConcreteBean() {
    		System.err.println("ConcreteBean实例对象被创建.......");
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		System.err.println("ConcreteBean实例对象默认name属性注入.........");
    		this.name = name;
    	}
    
    	/**
    	 * BeanNameAware:获取Bean在BeanFactory的名称：id
    	 */
    	@Override
    	public void setBeanName(String name) {
    		System.err.println("BeanNameAware:ConcreteBean实例对象在BeanFactory的名称:"+name);
    	}
    
    	/**
    	 * BeanFactoryAware:获取Bean所在的Beanfactory
    	 */
    	@Override
    	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
    		boolean flag = beanFactory.containsBean("concreteBean");  //使用BeanFactory的方法判断Bean是否存在
    		System.err.println("BeanfactoryAware:BeanFactory是否存在concreteBean定义："+flag);
    	}
    
    	/**
    	 * ApplicationContextAware:获取Bean实例所在的高级BeanFactory容器：ApplicationContext
    	 */
    	@Override
    	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    		boolean flag = applicationContext.containsBean("concreteBean");
    		System.err.println("ApplicationContextAware:ApplicationContext是否存在concreteBean定义："+flag);
    	}
    
    	/**
    	 * InitializingBean:Bean属性设置完成之后的自定义初始化工作
    	 */
    	@Override
    	public void afterPropertiesSet() throws Exception {
    		System.err.println("ConcreteBean完成属性设置，正在进行初始化........");
    	}
    
    	/**
    	 * DisposableBean:销毁Bean相关的资源:destroy-method属性
    	 */
    	@Override
    	public void destroy() throws Exception {
    		 System.err.println("IOC容器正在销毁Bean资源........");
    	}
    	
    	/**
    	 * 自定义初始化方法：init-method属性
    	 */
    	public void defineInitMethod(){
    		System.err.println("Bean正在自定义初始化......");
    	}
    }

**Bean后置处理器**：

package com.zhiwei.lifecycle;
    import java.util.Date;
    import org.springframework.beans.BeansException;
    import org.springframework.beans.factory.config.BeanPostProcessor;
    /**
     * BeanPostProcessor:后置处理器(针对所有的Bean实例) 作用：Bean完全实例化之前可以修改Bean的属性
     */
    public class BeanPostProcessorCase implements BeanPostProcessor {
    
    	/**
    	 * Bean初始化之前被调用
    	 */
    	public Object postProcessBeforeInitialization(Object object, String id) throws BeansException {
    
    		System.err.println("正在进行" + object + "实例初始化:,id =" + id + ",时间:" + new Date());
    		return object;
    	};
    
    	/**
    	 * Bean初始化之后被调用
    	 */
    	@Override
    	public Object postProcessAfterInitialization(Object object, String id) throws BeansException {
    		System.err.println("已经完成" + object + "实例初始化:,id =" + id + ",时间:" + new Date());
    		return object;
    	}
    }

测试类：

package com.zhiwei.lifecycle;
    import org.springframework.context.*;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    public class MainTest {
    
    	public static void main(String[] args) {
    		
    		ApplicationContext applicationContext=new ClassPathXmlApplicationContext("com/zhiwei/lifecycle/applicationContext.xml");
    		ConcreteBean concreteBean=(ConcreteBean) applicationContext.getBean("concreteBean");
    		System.out.println(concreteBean.getName());
    		
    		ConfigurableApplicationContext cac = (ConfigurableApplicationContext) applicationContext;
    		cac.close();  //关闭IOC容器
    	}
    }

控制台打印日志：

ConcreteBean实例对象被创建.......
    ConcreteBean实例对象默认name属性注入.........
    BeanNameAware:ConcreteBean实例对象在BeanFactory的名称:concreteBean
    BeanfactoryAware:BeanFactory是否存在concreteBean定义：true
    ApplicationContextAware:ApplicationContext是否存在concreteBean定义：true
    正在进行com.zhiwei.lifecycle.ConcreteBean@6ebc05a6实例初始化:,id =concreteBean,时间:Tue Feb 14 14:50:47 CST 2017
    ConcreteBean完成属性设置，正在进行初始化........
    Bean正在自定义初始化......
    已经完成com.zhiwei.lifecycle.ConcreteBean@6ebc05a6实例初始化:,id =concreteBean,时间:Tue Feb 14 14:50:47 CST 2017
    squirrel
    IOC容器正在销毁Bean资源........

转载于:https://my.oschina.net/yangzhiwei256/blog/3017084

[2019_Python_]: https://my.oschina.net/u/2663968/blog/3061697
[hot3.png]: /images/20220113/2c11c4920a0942b6bf4b86e0edb90063.png