Spring应用上下文中Bean的生命周期

Posted 2020-07-31 吥够魅力

Bean装载到Spring应用上下文的生命周期，如图：

 

Bean在Spring容器中从创建到销毁经历了若干个阶段，每一阶段都可以对Spring如何管理Bean进行个性化定制，以下我们通过代码去验证生命周期以及个性化定制方法；

BeanLife实现Aware接口、InitializingBean、DisposableBean接口,自定义生命周期中的方法。

/**
 * @name Bean生命周期
 */
public class BeanLife implements BeanNameAware,BeanFactoryAware,ApplicationContextAware,InitializingBean,DisposableBean{
    
    private String beanProperty;//私有属性
    
    private String beanName; //接收BeanNameAware的beanName传入
    private BeanFactory beanFactory;//接收BeanFactoryAware的beanFactory传入
    private ApplicationContext applicationContext;//接收ApplicationContextAware的applicationContext传入
    
    /**
     * 构造函数
     */
    public BeanLife(String beanProperty){
        System.out.println("BeanLife constructed with "+beanProperty+"......");
    }
    
    /**
     * bean属性get
     */
    public String getBeanProperty() {
        return beanProperty;
    }

    /**
     * bean填充属性
     */
    public void setBeanProperty(String beanProperty) {
        System.out.println("BeanLife setBeanProperty:"+beanProperty);
        this.beanProperty = beanProperty;
    }

    /**
     * init-method关联方法
     */
    public void begin(){
        System.out.println("init-method:begin()");
    }
    /**
     * destroy-method关联方法
     */
    public void end(){
        System.out.println("destroy-method:end()");
    }
    
    /**
     * 准备就绪的bean,使用Bean做些事情
     */
    public void doSomething(){
        System.out.println("BeanLife can be used: do something.");
    }
    
    /**
     * Spring将BeanFactory容器实例传入
     */
    public void setBeanFactory(BeanFactory arg0) throws BeansException {
        this.beanFactory=arg0;
        System.out.println("BeanFactoryAware---BeanLife setBeanFactory:"+this.beanFactory.toString());
    }
    
    /**
     * Spring将Bean的ID传入
     */
    public void setBeanName(String arg0) {
        this.beanName = arg0;
        System.out.println("BeanNameAware---BeanLife setBeanName:"+this.beanName);
    }
    
    /**
     * Spring将应用上下文的引用传入
     */
    public void setApplicationContext(ApplicationContext arg0)
            throws BeansException {
        this.applicationContext = arg0;
        System.out.println("ApplicationContextAware---BeanLife setApplicationContext:"+this.applicationContext.getApplicationName());
    }

    /**
     * 属性设置完毕后
     */
    public void afterPropertiesSet() throws Exception {
        System.out.println("InitializingBean---After SetProperties");
    }
    /**
     * Bean销毁
     */
    public void destroy() throws Exception {
        System.out.println("DisposableBean---BeanLife Bean destroy.");
    }
}

自定义一个BeanPostProcessor进行监控Spring容器Bean实例化注入时的回调方法定制

/**
 * @name BeanPostProcessor实现
 */
public class BeanLifePostProcessor implements BeanPostProcessor{

    /**
     * 实例化、依赖注入完毕，在调用显示的初始化之前完成一些定制的初始化任务
     * @param arg0 Bean对象
     * @param arg1 Bean的ID
     */
    public Object postProcessBeforeInitialization(Object arg0, String arg1)
            throws BeansException {
        System.out.println("BeanPostProcessor---Before "+arg1+"\'s Initialization ");
        return arg0;
    }
    
    /**
     * 实例化、依赖注入、初始化完毕时执行
     * @param arg0 Bean对象
     * @param arg1 Bean的ID
     */
    public Object postProcessAfterInitialization(Object arg0, String arg1)
            throws BeansException {

        System.out.println("BeanPostProcessor---After "+arg1+"\'s Initialization");
        return arg0;
    }
    
}

applicationContext.xml配置

<!-- BeanLife -->
<bean id="beanlife" class="com.wjx.betalot.BeanLife" init-method="begin" destroy-method="end">
    <constructor-arg value="beanlife construct param"></constructor-arg>
    <property name="beanProperty" value="beanlife cycle"></property>
</bean>
<!-- beanPostProcessor -->
<bean id="beanPostProcessor" class="com.wjx.betalot.BeanLifePostProcessor"></bean>

验证测试：

public static void main( String[] args ) throws Exception{

        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
        BeanLife beanlife = (BeanLife) context.getBean("beanlife");
        beanlife.doSomething();
        //销毁bean
        ((ClassPathXmlApplicationContext)context).registerShutdownHook();
}

测试结果：

BeanLife constructed with beanlife construct param......
BeanLife setBeanProperty:beanlife cycle
BeanNameAware---BeanLife setBeanName:beanlife
BeanFactoryAware---BeanLife setBeanFactory:org.springframework.beans.factory.support.DefaultListableBeanFactory@5eed2fce: defining beans [beanlife,beanPostProcessor]; root of factory hierarchy
ApplicationContextAware---BeanLife setApplicationContext:
BeanPostProcessor---Before beanlife\'s Initialization 
InitializingBean---After SetProperties
init-method:begin()
BeanPostProcessor---After beanlife\'s Initialization
BeanLife can be used: do something.
DisposableBean---BeanLife Bean destroy.
destroy-method:end()

可对照Bean的生命周期图，进行验证。