spring bean初始化和销毁

spring bean的创建与消亡由spring容器进行管理，除了使用<bean><property/></bean>进行简单的属性配置之外，spring支持更人性化的方法

• @PostConstruct @PreDestroy
• xml的init-method和destroy-method
• 实现InitializingBean和DisposableBean接口 

public class BeanInitMethod implements InitializingBean, DisposableBean {

    private int step;

    public int getStep() {
        return step;
    }

    public void setStep(int step) {
        this.step = step;
    }

    @PostConstruct
    public void postConstruct() {
        System.out.println("initialized by annotation");
        step = 1;
    }

    @PreDestroy
    public void predestroy() {
        System.out.println("destroyed by annotation");
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("initialized by interface");
        step = 2;
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("destroyed by interface");
    }

    public void initFunc() {
        System.out.println("initialized by xml");
        step = 3;
    }

    public void destroyFunc() {
        System.out.println("destroyed by xml");
    }

    public static void main(String[] argv) {
        BeanInitMethod beanInitMethod;
        BeanFactory beanFactory = new ClassPathXmlApplicationContext("applicationContext.xml");
        beanInitMethod = (BeanInitMethod) beanFactory.getBean("initTestBean");

        System.out.println("step=" + beanInitMethod.getStep());

        System.out.println("program is done");
    }

}

对于“注解方式”还需要开启注解的支持，在上下文xml配置文件加入

<context:annotation-config/>

对于xml配置方式，则需要加入

<bean id="initTestBean" class="edu.xhyzjiji.cn.spring.BeanInitMethod" init-method="initFunc" destroy-method="destroyFunc"/>

当bean实例被创建时，会依据以下顺序执行初始化

initialized by annotation
initialized by interface
initialized by xml
step=3
program is done