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;
}
}