Webx启动流程

1 WebxContextLoaderListener

      Webx Framework 通过配置在web.xml中的WebxContextLoaderListener来初始化Spring
    
     <!-- 装载/WEB-INF/webx.xml, /WEB-INF/webx-*.xml -->
    <listener>
        <listener-class><strong>com.alibaba.citrus.webx.context.WebxContextLoaderListener</strong></listener-class>
    </listener>
  WebxContextLoaderListener 是ContextLoaderListener的派生类。它定制了自己的ContextLoader——WebxComponentsLoader}       
       
        
<span style="background-color: rgb(240, 240, 240);">  <pre name="code" class="html"> public class WebxContextLoaderListener extends ContextLoaderListener {</span>    
     @Override
    protected final ContextLoader createContextLoader() {
       <strong> return new WebxComponentsLoader()</strong> {

            @Override
            protected Class<? extends WebxComponentsContext> getDefaultContextClass() {
                Class<? extends WebxComponentsContext> defaultContextClass = WebxContextLoaderListener.this
                        .getDefaultContextClass();

                if (defaultContextClass == null) {
                    defaultContextClass = super.getDefaultContextClass();
                }

                return defaultContextClass;
            }
        };
    }

    protected Class<? extends WebxComponentsContext> getDefaultContextClass() {
        return null;
    }
}

WebxComponentsLoader

其与基类ContextLoader相比,定义了一些自己的字段:

     <pre name="code" class="html">public class WebxComponentsLoader extends ContextLoader {
    private final static Logger log = LoggerFactory.getLogger(WebxComponentsLoader.class);
    private String webxConfigurationName;
    private ServletContext servletContext;
    private WebApplicationContext componentsContext;
    private WebxComponentsImpl components;
    ...
}


之后,使用代理模式由WebxComponentsLoader调用initWebApplicationContext继续初始化过程。实际上,initWebApplicationContext是其基类ContextLoader的方法,而WebxComponentsLoader重写了此方法
  
public WebApplicationContext initWebApplicationContext(ServletContext servletContext) throws IllegalStateException,
            BeansException {
        this.servletContext = servletContext;
        init();

        return super.initWebApplicationContext(servletContext);
    }

        这里,WebxComponentsLoader获取了servletContext, 通过init方法设置context中WebxConfiguration的名称。然后继续调用基类的同名方法,root application开始初始化。
    
public WebApplicationContext initWebApplicationContext(ServletContext servletContext) {
		if (servletContext.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE) != null) {
			throw new IllegalStateException(
					"Cannot initialize context because there is already a root application context present - " +
					"check whether you have multiple ContextLoader* definitions in your web.xml!");
		}

		Log logger = LogFactory.getLog(ContextLoader.class);
		servletContext.log(<strong>"Initializing Spring root WebApplicationContext"</strong>);
		if (logger.isInfoEnabled()) {
			logger.info(<strong>"Root WebApplicationContext: initialization started"</strong>);
		}
		long startTime = System.currentTimeMillis();

		try {
			// Determine parent for root web application context, if any.
			ApplicationContext parent = loadParentContext(servletContext);

			// Store context in local instance variable, to guarantee that
			// it is available on ServletContext shutdown.
			<strong>this.context = createWebApplicationContext(servletContext, parent);</strong>
			servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);

			ClassLoader ccl = Thread.currentThread().getContextClassLoader();
			if (ccl == ContextLoader.class.getClassLoader()) {
				currentContext = this.context;
			}
			else if (ccl != null) {
				currentContextPerThread.put(ccl, this.context);
			}

			if (logger.isDebugEnabled()) {
				logger.debug("Published root WebApplicationContext as ServletContext attribute with name [" +
						WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE + "]");
			}
			if (logger.isInfoEnabled()) {
				long elapsedTime = System.currentTimeMillis() - startTime;
				logger.info("Root WebApplicationContext: initialization completed in " + elapsedTime + " ms");
			}

			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;
		}
	}
此方法中最重要的部分是对应用上下文WebApplicationContext的创建

WebApplicationContext

       在createWebApplicationContext方法中,定义了ConfigurableWebApplicationContext 对象wac.
       wac在返回给ContextLoader前,主要完成以下几个过程:
      
                wac.setParent(parent);
		wac.setServletContext(sc);
		wac.setConfigLocation(sc.getInitParameter(CONFIG_LOCATION_PARAM));
		customizeContext(sc, wac);
		wac.refresh();
 
       经过前几个步骤的准备工作后,由refresh方法初始化所有bean。
      而refresh方法使用工厂模式刷新beans。
  
public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			prepareRefresh();

			// Tell the subclass to refresh the internal bean factory.
			<strong>ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();</strong>

			// Prepare the bean factory for use in this context.
			prepareBeanFactory(beanFactory);

			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();

				// Initialize other special beans in specific context subclasses.
				onRefresh();

				// Check for listener beans and register them.
				registerListeners();

				// Instantiate all remaining (non-lazy-init) singletons.
				<strong>finishBeanFactoryInitialization(beanFactory);</strong>

				// 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;
			}
		}
	}

ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); 这一步骤获取了/WEB-INF/ 目录下所有配置文件。
finishBeanFactoryInitialization(beanFactory);   完成整个beanfactory的初始化过程。
另外,此方法通过递归方式初始化了所有子应用。


初始化流程草图如下:

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