Webx3 初始化过程学习
这两天利用空余时间学习了webx3.0，基于spring mvc开发的一款mvc；由于对webx2.0以及spring mvc没有进行过深入的研究，在学习webx3.0的时候，肯定会出现理解上的偏差甚至错误，希望大家积极提出，有问题才是进步的动力；以前很少写文章，文笔不好，还请大家见谅，:)！无废话，开始：
Web.xml,tomcat加载war包开始：
<!-- 装载/WEB-INF/webx.xml, /WEB-INF/webx-*.xml --> <listener> <listener-class>com.alibaba.citrus.webx.context.WebxContextLoaderListener</listener-class></listener>?
其中WebxContextLoaderListener 信息如下：
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import org.springframework.web.context.ContextLoader;import org.springframework.web.context.ContextLoaderListener;public class WebxContextLoaderListener extends ContextLoaderListener {……?WebxContextLoaderListener继承了spring mvc的监听类：ContextLoaderListener；
可想而知，容器启动时，将调用： contextInitialized(ServletContextEvent event)? 该方法，如下：
public void contextInitialized(ServletContextEvent event) { //1.初始化加载类this.contextLoader = createContextLoader(); //2.出示话web上下文this.contextLoader.initWebApplicationContext(event.getServletContext());}?
由于WebxContextLoaderListener覆盖了createContextLoader()方法，
@Override protected final ContextLoader createContextLoader() { return new WebxComponentsLoader() { @Override protected Class<?> getDefaultContextClass() { Class<?> defaultContextClass = WebxContextLoaderListener.this.getDefaultContextClass(); if (defaultContextClass == null) { defaultContextClass = super.getDefaultContextClass(); } return defaultContextClass; } }; }?contextLoader已经是这个了：WebxComponentsLoader 重点关注这个类，
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public class WebxComponentsLoader extends ContextLoader
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将负责加载webx中的componet组件，还继承了spring mvc的加载类 ContextLoader，
?所以initWebApplicationContext 就在子类WebxComponentsLoader中执行了：
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@Override public WebApplicationContext initWebApplicationContext(ServletContext servletContext) throws IllegalStateException, BeansException { this.servletContext = servletContext; init(); //开始spring mvc加载… return super.initWebApplicationContext(servletContext); }?经过自己的init后
? super.initWebApplicationContext(servletContext);
? 又回到父类里面去了：
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public WebApplicationContext initWebApplicationContext(ServletContext servletContext)throws IllegalStateException, BeansException { //.....先忽略long startTime = System.currentTimeMillis();try {// Determine parent for root web application context, if any. //1.先找parent，一般是空的吧ApplicationContext parent = loadParentContext(servletContext);// Store context in local instance variable, to guarantee that// it is available on ServletContext shutdown. //2.创建this.context = createWebApplicationContext(servletContext, parent); //3.设为rootservletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);currentContextPerThread.put(Thread.currentThread().getContextClassLoader(), this.context);//再忽略...return this.context;}catch (RuntimeException ex) {logger.error("Context initialization failed", ex);servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, ex);throw ex;}catch (Error err) {logger.error("Context initialization failed", err);servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, err);throw err;}}?createWebApplicationContext方法主要包括下面4步：
?1.找到上下文类
Class contextClass = determineContextClass(servletContext);
?定位上下文class，这个class可配置；这个方法被WebxContextLoaderListener覆盖，最后返回的class：
return WebxComponentsContext.class;
第二个重要的类出现：WebxComponentsContext
WebxComponentsContext
继承
WebxApplicationContext（webx重写）
继承
XmlWebApplicationContext（spring原生）
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2.实例化上下文类
ConfigurableWebApplicationContext wac = (ConfigurableWebApplicationContext) BeanUtils.instantiateClass(contextClass);wac.setParent(parent);wac.setServletContext(servletContext);wac.setConfigLocation(servletContext.getInitParameter(CONFIG_LOCATION_PARAM));
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3.可以自定义操作上下文
customizeContext(servletContext, wac);//被子类覆盖
?此方法也被WebxContextLoaderListener覆盖：
protected void customizeContext(ServletContext servletContext, ConfigurableWebApplicationContext componentsContext) { this.componentsContext = componentsContext; if (componentsContext instanceof WebxComponentsContext) {// componentsContext就是上面实例化的上下文，铁定是WebxComponentsContext类 ((WebxComponentsContext) componentsContext).setLoader(this);//为load webx组件配置文件而准备 }}?4.初始化IOC容器
wac.refresh();
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看到熟悉的refush方法了，ConfigurableWebApplicationContext是没有refush方法，AbstractApplicationContext这个类有refush方法：
public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {// Prepare this context for refreshing.prepareRefresh();// Tell the subclass to refresh the internal bean factory.ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();// Prepare the bean factory for use in this context.prepareBeanFactory(beanFactory);try {// Allows post-processing of the bean factory in context subclasses.postProcessBeanFactory(beanFactory); //被覆盖，重点关注 ?// 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();// Initialize other special beans in specific context subclasses.onRefresh();// Check for listener beans and register them.registerListeners();// Instantiate all remaining (non-lazy-init) singletons.finishBeanFactoryInitialization(beanFactory);// Last step: publish corresponding event.finishRefresh(); //被覆盖，重点关注 }catch (BeansException ex) {// Destroy already created singletons to avoid dangling resources.beanFactory.destroySingletons();// Reset 'active' flag.cancelRefresh(ex);// Propagate exception to caller.throw ex;}}}?postProcessBeanFactory(beanFactory);有覆盖吗？有！
实例化前，webx覆盖了此方法来，进行把webx组件实例放入spring中，怎么放？哪里执行？
((WebxComponentsContext) componentsContext).setLoader(this);
?这里看出是WebxComponentsLoader来进行这个工作：
/** * 在创建beanFactory之初被调用。 * * @param webxComponentsContext */ public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { // 由于初始化components依赖于webxConfiguration，而webxConfiguration可能需要由PropertyPlaceholderConfigurer来处理， // 此外，其它有一些BeanFactoryPostProcessors会用到components， // 因此components必须在PropertyPlaceholderConfigurer之后初始化，并在其它BeanFactoryPostProcessors之前初始化。 // // 下面创建的WebxComponentsCreator辅助类就是用来确保这个初始化顺序： // 1. PriorityOrdered - PropertyPlaceholderConfigurer // 2. Ordered - WebxComponentsCreator // 3. 普通 - 其它BeanFactoryPostProcessors BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(WebxComponentsCreator.class); builder.addConstructorArgValue(this); BeanDefinition componentsCreator = builder.getBeanDefinition(); componentsCreator.setAutowireCandidate(false); BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; String name = SpringExtUtil.generateBeanName(WebxComponentsCreator.class.getName(), registry); registry.registerBeanDefinition(name, componentsCreator); }?一个内部类，WebxComponentsCreator辅助类就是用来确保初始化顺序，见上面：
public static class WebxComponentsCreator implements BeanFactoryPostProcessor, Ordered { private final WebxComponentsLoader loader; public WebxComponentsCreator(WebxComponentsLoader loader) { this.loader = assertNotNull(loader, "WebxComponentsLoader"); } public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { if (loader.components == null) { WebxComponentsImpl components = loader.createComponents(loader.getParentConfiguration(), beanFactory); AbstractApplicationContext wcc = (AbstractApplicationContext) components.getParentApplicationContext(); wcc.addApplicationListener(new SourceFilteringListener(wcc, components)); loader.components = components; } } public int getOrder() { return Ordered.LOWEST_PRECEDENCE; } }?初始化components：
/** * 初始化components。 */ private WebxComponentsImpl createComponents(WebxConfiguration parentConfiguration, ConfigurableListableBeanFactory beanFactory) { //1.取得一组关于components的配置，也就是component的配置文件，ComponentsConfigImpl中 ComponentsConfig componentsConfig = getComponentsConfig(parentConfiguration); // 2.假如isAutoDiscoverComponents==true，试图自动发现components Map<String, String> componentNamesAndLocations = findComponents(componentsConfig, getServletContext()); // 3.取得特别指定的components Map<String, ComponentConfig> specifiedComponents = componentsConfig.getComponents(); // 4.实际要初始化的comonents，为上述两种来源的并集 Set<String> componentNames = createTreeSet(); componentNames.addAll(componentNamesAndLocations.keySet()); componentNames.addAll(specifiedComponents.keySet()); // 5.创建root controller WebxRootController rootController = componentsConfig.getRootController(); if (rootController == null) { rootController = (WebxRootController) BeanUtils.instantiateClass(componentsConfig.getRootControllerClass()); } // 6.创建并将components对象置入resolvable dependencies，以便注入到需要的bean中 WebxComponentsImpl components = new WebxComponentsImpl(componentsContext, componentsConfig .getDefaultComponent(), rootController, parentConfiguration); beanFactory.registerResolvableDependency(WebxComponents.class, components); // 7.初始化每个component for (String componentName : componentNames) { ComponentConfig componentConfig = specifiedComponents.get(componentName); String componentPath = null; WebxController controller = null; if (componentConfig != null) { componentPath = componentConfig.getPath(); controller = componentConfig.getController(); } if (controller == null) { controller = (WebxController) BeanUtils.instantiateClass(componentsConfig.getDefaultControllerClass()); } WebxComponentImpl component = new WebxComponentImpl(components, componentName, componentPath, componentName .equals(componentsConfig.getDefaultComponent()), controller, getWebxConfigurationName()); components.addComponent(component); prepareComponent(component, componentNamesAndLocations.get(componentName)); } return components; }?怎么找到components，只要找到对应配置项即可
public String getComponentConfigurationLocationPattern() { return componentConfigurationLocationPattern == null ? "/WEB-INF/webx-*.xml" : componentConfigurationLocationPattern; }//找到了配置文件，接下去要解析了，里面实现比较啰嗦，@#￥#@￥@#￥一大堆，返回?未完待续......
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学习了webx3.0和spring mvc如何结果工作，对于定制web mvc有帮助！
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