【spring mvc】application context中【bean】的生命周期
生命周期过程
主要分为四部分:
一、实例化
二、初始化
8.如果有Bean实现了BeanPostProcessor接口,则会回调该接口的postProcessBeforeInitialzation()方法对 bean进行加工操作,这个非常重要, spring 的 AOP 就是用它实现的。
9.如果Bean实现了InitializingBean接口,则会回调该接口的afterPropertiesSet()方法,实现 InitializingBean接口必须实现afterPropertiesSet方法。(这个方法的作用是啥,还不太清楚)
10.如果Bean配置了init-method方法,则会执行init-method配置的方法。
11.如果有Bean实现了BeanPostProcessor接口,则会回调该接口的postProcessAfterInitialization()方法。
三、执行具体的操作
12.经过流程9之后,就可以正式使用该Bean了,对于scope为singleton的Bean,Spring的ioc容器中会缓存一份该bean的实例,而对于scope为prototype的Bean,每次被调用都会new一个新的对象,期生命周期就交给调用方管理了,不再是Spring容器进行管理了。
然后就可以用这个Bean想干啥干啥了。。。
四、销毁
13.容器关闭后,如果Bean实现了DisposableBean接口,则会回调该接口的destroy()方法。
14.如果Bean配置了destroy-method方法,则会执行destroy-method配置的方法,至此,整个Bean的生命周期结束。
代码解析
示例代码地址:https://github.com/handv/SpringMVCDemo/tree/master/SpringMVC_000
代码执行结果:
开始初始化容器
九月 25, 2016 10:44:50 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@b4aa453: startup date [Sun Sep 25 22:44:50 CST 2016]; root of context hierarchy
九月 25, 2016 10:44:50 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [com/test/spring/life/applicationContext.xml]
Person类构造方法
set方法被调用
setBeanName被调用,beanName:person1
setBeanFactory被调用,beanFactory
setApplicationContext被调用
postProcessBeforeInitialization被调用
afterPropertiesSet被调用
myInit被调用
postProcessAfterInitialization被调用
xml加载完毕
name is :jack
关闭容器
九月 25, 2016 10:44:51 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@b4aa453: startup date [Sun Sep 25 22:44:50 CST 2016]; root of context hierarchy
destory被调用
myDestroy被调用
1、AbstractAutowireCapableBeanFactory.populateBean
protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) {
...
if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
//这里用到了InstantiationAwareBeanPostProcessor
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
//这里用到了postProcessAfterInstantiation方法
if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
continueWithPropertyPopulation = false;
break;
}
}
}
}
...
boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
if (hasInstAwareBpps || needsDepCheck) {
PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
if (hasInstAwareBpps) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
//注册InstantiationAwareBeanPostProcessor接口
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
//调用InstantiationAwareBeanPostProcessor的postProcessPropertyValues方法
pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
if (pvs == null) {
return;
}
}
}
}
if (needsDepCheck) {
checkDependencies(beanName, mbd, filteredPds, pvs);
}
}
//该处反射执行Bean的setxxx方法
applyPropertyValues(beanName, mbd, bw, pvs);
}
2、AbstractAutowireCapableBeanFactory.invokeAwareMethods()
private void invokeAwareMethods(final String beanName, final Object bean) {
if (bean instanceof Aware) {
if (bean instanceof BeanNameAware) {
//设置BeanName
((BeanNameAware) bean).setBeanName(beanName);
}
if (bean instanceof BeanClassLoaderAware) {
((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader());
}
if (bean instanceof BeanFactoryAware) {
//设置BeanFactory
((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);
}
}
}
3、AbstractAutowireCapableBeanFactory.initializeBean
/**
* Initialize the given bean instance, applying factory callbacks
* as well as init methods and bean post processors.
* <p>Called from {@link #createBean} for traditionally defined beans,
* and from {@link #initializeBean} for existing bean instances.
* @param beanName the bean name in the factory (for debugging purposes)
* @param bean the new bean instance we may need to initialize
* @param mbd the bean definition that the bean was created with
* (can also be {@code null}, if given an existing bean instance)
* @return the initialized bean instance (potentially wrapped)
* @see BeanNameAware
* @see BeanClassLoaderAware
* @see BeanFactoryAware
* @see #applyBeanPostProcessorsBeforeInitialization
* @see #invokeInitMethods
* @see #applyBeanPostProcessorsAfterInitialization
*/
protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
invokeAwareMethods(beanName, bean);
return null;
}
}, getAccessControlContext());
}
else {
invokeAwareMethods(beanName, bean);
}
Object wrappedBean = bean;
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
}
try {
invokeInitMethods(beanName, wrappedBean, mbd);
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null),
beanName, "Invocation of init method failed", ex);
}
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}
后续代码可以看源码的注释,先不看了,太多了
参考:http://www.jianshu.com/p/3944792a5fff
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