spring源码阅读（五）之ApplicationContext

上一篇介绍了基本的IOC容器BeanFactory以及常用的继承类XmlBeanFactory，但那时基本的一个容器，Spring扩展一个程序员常用的的一个容器ApplicationContext

public interface ApplicationContext extends EnvironmentCapable, ListableBeanFactory, HierarchicalBeanFactory,MessageSource, ApplicationEventPublisher, ResourcePatternResolver {

是一个高级的IOC容器。

扩展MessageSource，支持国际化

扩展ApplicationEventPublisher提供bean的生命周期管理

类似于上一篇介绍BeanFactory的子类XmlBeanFactory一样，这一篇介绍FileSystemXmlApplicationContext

public class FileSystemXmlApplicationContext extends AbstractXmlApplicationContext 

它是AbstractXmlApplicationContext的子类。他有2个主要的功能，一个是

public FileSystemXmlApplicationContext(String[] configLocations, boolean refresh, ApplicationContext parent)throws BeansException {super(parent);setConfigLocations(configLocations);if (refresh) {refresh();}}

刷新IOC容器。这个AbstractApplicationContext类里面的refresh()方法异常的复杂。

public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {<span style="color: rgb(0, 130, 0); font-family: Monaco, 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', Consolas, 'Courier New', monospace; line-height: 18px; background-color: rgb(250, 250, 250);">//准备启动spring容器，设置容器的启动日期和活动标志</span>prepareRefresh();<span class="comment" style="color: rgb(0, 130, 0); padding: 0px; margin: 0px; width: auto; border: 0px; font-family: Monaco, 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', Consolas, 'Courier New', monospace; line-height: 18px; background-color: rgb(250, 250, 250);">//获得容器ApplicationContext的子类BeanFactory。步骤如下：如果已经有了BeanFactory就销毁它里面的单例Bean并关闭这个BeanFactory。2.创建一个新的BeanFactory。3.对这个BeanFactory进行定制（customize),如allowBeanDefinitionOverriding，allowCircularReferences。4.转载BeanDefinitions(读取配置文件，将xml转换成对应得BeanDefinition)。5.检查是否同时启动了两个BeanFactory。</span><span style="font-family: Monaco, 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', Consolas, 'Courier New', monospace; line-height: 18px; background-color: rgb(250, 250, 250);">  </span>ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();prepareBeanFactory(beanFactory);<pre name="code" class="html"><span class="comment" style="color: rgb(0, 130, 0); padding: 0px; margin: 0px; width: auto; border: 0px; font-family: Monaco, 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', Consolas, 'Courier New', monospace; line-height: 18px; background-color: rgb(250, 250, 250);">//配置BeanFactory（就是将ApplicationContext的一些属性配置到BeanFactory上吧）。这里做了很多事情，可以看看其源码，比较重要的如设置classLoader；将BeanPostProcess注册到BeanFactory里。</span><span style="font-family: Monaco, 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', Consolas, 'Courier New', monospace; line-height: 18px; background-color: rgb(250, 250, 250);">  </span>

try {// Allows post-processing of the bean factory in context subclasses.postProcessBeanFactory(beanFactory);// Invoke factory processors registered as beans in the context.invokeBeanFactoryPostProcessors(beanFactory);// Register bean processors that intercept bean creation.registerBeanPostProcessors(beanFactory);// Initialize message source for this context.initMessageSource();// Initialize event multicaster for this context.initApplicationEventMulticaster();/初始化单例的Bean，并将其保存起来。  onRefresh();// Check for listener beans and register them.registerListeners();// Instantiate all remaining (non-lazy-init) singletons.finishBeanFactoryInitialization(beanFactory);// Last step: publish corresponding event.finishRefresh();}catch (BeansException ex) {// Destroy already created singletons to avoid dangling resources.destroyBeans();// Reset 'active' flag.cancelRefresh(ex);// Propagate exception to caller.throw ex;}}}

这个方法先mark一下，以后再慢慢解析，因为还有一些东西没看懂。

另外一个功能是和XmlBeanFactory通过xml加载资源

@Overrideprotected Resource getResourceByPath(String path) {if (path != null && path.startsWith("/")) {path = path.substring(1);}return new FileSystemResource(path);}