Spring初始化Bean和销毁Bean时做处理

在配置bean实例时，xml中设置init和destroy方法：

<bean class="com.test.Demo" init-method="init" destroy-method="destroy"/>

public class Demo{
    public void init() {
        System.out.println("Demo.class init method ...");
    }
    public void destroy() {
        System.out.println("Demo.class destroy method ...");
    }
}

bean实现BeanPostProcessor接口，实现接口中的postProcessBeforeInitialization(初始化之前执行)，postProcessAfterInitialization(bean初始化之后执行）

public class Demo implements BeanPostProcessor {  
   @Override  
   public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {  
       System.out.println("对象" + beanName + "开始初始化");  
       return bean;  
   }  

   @Override  
   public Object postProcessAfterInitialization(Object bean, String beanName)  throws BeansException {  
       System.out.println("对象" + beanName + "初试化完成");  
       return bean;  
   }  
}

<bean id="demo" class="com.test.Demo" />

bean实现InitializingBean和DisposableBean接口

public class Demo implements InitializingBean, DisposableBean {
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("Demo.class init method ...");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("Demo.class destroy method ...");
    }
}

<bean id="demo" class="com.test.Demo" />

使用@PostConstruct和@PreDestroy注解

@Component
public class Demo {
    @PostConstruct
    public void init() {
        System.out.println("Demo .class init method ...");
    }

    @PreDestroy
    public void destroy() {
        System.out.println("Demo .class destroymethod ...");
    }
}