spring bean初始化和銷燬

spring bean的建立與消亡由spring容器進行管理，除了使用<bean><property/></bean>進行簡單的屬性配置以外，spring支持更人性化的方法

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

 1 public class BeanInitMethod implements InitializingBean, DisposableBean {
 2 
 3     private int step;
 4 
 5     public int getStep() {
 6         return step;
 7     }
 8 
 9     public void setStep(int step) {
10         this.step = step;
11     }
12 
13     @PostConstruct
14     public void postConstruct() {
15         System.out.println("initialized by annotation");
16         step = 1;
17     }
18 
19     @PreDestroy
20     public void predestroy() {
21         System.out.println("destroyed by annotation");
22     }
23 
24     @Override
25     public void afterPropertiesSet() throws Exception {
26         System.out.println("initialized by interface");
27         step = 2;
28     }
29 
30     @Override
31     public void destroy() throws Exception {
32         System.out.println("destroyed by interface");
33     }
34 
35     public void initFunc() {
36         System.out.println("initialized by xml");
37         step = 3;
38     }
39 
40     public void destroyFunc() {
41         System.out.println("destroyed by xml");
42     }
43 
44     public static void main(String[] argv) {
45         BeanInitMethod beanInitMethod;
46         BeanFactory beanFactory = new ClassPathXmlApplicationContext("applicationContext.xml");
47         beanInitMethod = (BeanInitMethod) beanFactory.getBean("initTestBean");
48 
49         System.out.println("step=" + beanInitMethod.getStep());
50 
51         System.out.println("program is done");
52     }
53 
54 }

對於「註解方式」還須要開啓註解的支持，在上下文xml配置文件加入

<context:annotation-config/>

對於xml配置方式，則須要加入

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

當bean實例被建立時，會依據如下順序執行初始化

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