Bean在Spring容器中的生命周期

配置在Spring中的Bean在Spring容器中从加载到销毁会经历那些过程呢?如果实现一些特定的Spring接口,这些特定接口的方法会在什么时候被调用呢?本文简单介绍一下这些过程.

Bean在Spring容器中的生命周期如下图所示:

1,调用Bean的构造函数(或者工厂方法)实例化Bean.
2,对Bean的成员变量赋值.
3,如果Bean实现了BeanNameAware,调用Bean的setBeanName方法.
4,如果Bean实现了BeanFactoryAware,调用Bean的setBeanFactory方法.
5,如果Bean实现了ApplicationContextAware,调用Bean的setApplicationContext方法.
6,如果容器中配置了BeanPostProcessor,调用BeanPostProcessor的postProcessBeforeInitialization方法(如果有多个BeanPostProcessor,调用每一个BeanPostProcessor的postProcessBeforeInitialization方法).
6,如果Bean实现了InitializingBean,调用Bean的afterPropertiesSet方法.
7,如果Bean配置了init-method方法,调用init-method配置的Bean方法.
8,如果容器中配置了BeanPostProcessor,调用BeanPostProcessor的postProcessAfterInitialization方法.(如果有多个BeanPostProcessor,调用每一个BeanPostProcessor的postProcessAfterInitialization方法).
9,Bean处于可以使用的状态.
10,Spring容器关闭.
11,4,如果Bean实现了DisposableBean,调用Bean的destroy方法.
12,如果Bean配置了destroy-method方法,调用destroy-method配置的Bean的方法.

实例:LifeCycleBean implements InitializingBean, DisposableBean,BeanNameAware,BeanFactoryAware, ApplicationContextAware,配置了init-method="init" destroy-method="cleanup",容器中有两个BeanPostProcessor

public class LifeCycleBean implements InitializingBean, DisposableBean,  
        BeanNameAware,BeanFactoryAware, ApplicationContextAware {  
    private String str = "default";  
    public LifeCycleBean() {  
        System.out.println("construct LifecycleBean ***************");  
    }  
    public LifeCycleBean(String str) {  
        this.str = str;  
    }  
    public String getStr() {  
        return str;  
    }  
    public void setStr(String str) {  
        System.out.println("setStr ***************");  
        this.str = str;  
    }  
    public void init() {  
        System.out.println("init mtd ***************");  
    }  
    public void cleanup() {  
        System.out.println("cleanup mtd ***************");  
    }  
      
    public void afterPropertiesSet() throws Exception {  
        System.out.println("afterPropertiesSet ***************");  
    }  
    public void destroy() throws Exception {  
        System.out.println("destroy ***************");  
    }     
    public void setApplicationContext(ApplicationContext arg0)  
            throws BeansException {  
        System.out.println("setApplicationContext***************");  
    }  
    public void setBeanFactory(BeanFactory arg0) throws BeansException {  
        System.out.println("setBeanFactory***************");  
    }  
    public void setBeanName(String arg0) {  
        System.out.println("setBeanName***************" + arg0);              
    }  
}  
public class MyBeanPostProcessor implements BeanPostProcessor {  
    public Object postProcessBeforeInitialization(Object bean, String beanName)  
            throws BeansException {  
        System.out.println("************** MyBeanPostProcessor postProcessBeforeInitialization Bean '" + beanName);  
        return bean;  
    }  
    public Object postProcessAfterInitialization(Object bean, String beanName)  
            throws BeansException {  
        System.out.println("************** MyBeanPostProcessor postProcessAfterInitialization Bean '" + beanName);  
        return bean;  
    }  
}  

Spring配置

ApplicationContext ctx = new ClassPathXmlApplicationContext("classpath:conf/bfactoryCtx1.xml");  
((ClassPathXmlApplicationContext)ctx).registerShutdownHook();  
LifeCycleBean bean1 = ctx.getBean("lifeCycleBean",LifeCycleBean.class);  
System.out.println("***********" + bean1 +  "   " + bean1.getStr());  

输出结果如下:

construct LifecycleBean ***************  
setStr ***************       #1  
setBeanName***************lifeCycleBean  
setBeanFactory***************  
setApplicationContext***************  
************** MyBeanPostProcessor postProcessBeforeInitialization Bean 'lifeCycleBean  #2  
************** MyBeanPostProcessor1 postProcessBeforeInitialization Bean 'lifeCycleBean #2  
afterPropertiesSet ***************  
init mtd ***************  
************** MyBeanPostProcessor postProcessAfterInitialization Bean 'lifeCycleBean   #2  
************** MyBeanPostProcessor1 postProcessAfterInitialization Bean 'lifeCycleBean  #2  
***********com.test.spring.beanfactoryCtx.LifeCycleBean@157fb52   test4                 #3  
destroy ***************  
cleanup mtd ***************  

#1为成员变量赋值的步骤
#2如果有多个BeanPostProcessor的话,每一个BeanPostProcessor都会被调用一次.
#3Bean 被客户端代码使用