Inside-springframework-XmlWebApplicationContext

Inside-springframework-XmlWebApplicationContext

 

/*****************段落1********************/

☆ 起势

 

★      public class ContextLoaderListener implements ServletContextListener {

public void contextInitialized(ServletContextEvent event) {

     this.contextLoader = createContextLoader();

     this.contextLoader.initWebApplicationContext(event.getServletContext()); (1)

}

}

★      public class ContextLoader {

public WebApplicationContext initWebApplicationContext(ServletContext servletContext)

         throws IllegalStateException, BeansException {

 

         this.context = createWebApplicationContext(servletContext, parent);(2)

        

         //将生成的ApplicationContext对象存入servletContext

         servletContext.setAttribute(

             WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE,

this.context);

}

 

protected WebApplicationContext createWebApplicationContext(

         ServletContext servletContext, ApplicationContext parent) throws BeansException {

     //通过属性文件动态加载ApplicationContext类

// contextClass= XmlWebApplicationContext

Class contextClass = determineContextClass(servletContext);

 

//值得学习的地方：Class. isAssignableFrom(Class<?> cls)

//  判定此 Class 对象所表示的类或接口与指定的 Class 参数所表示的类或接

//口是否相同，或是否是其超类或超接口。

if (!ConfigurableWebApplicationContext.class.isAssignableFrom(contextClass)) {

    throw new ApplicationContextException("Custom context class [" +

contextClass.getName() +"] is not of type ConfigurableWebApplicationContext");

}

ConfigurableWebApplicationContext wac = (ConfigurableWebApplicationContext)

BeanUtils.instantiateClass(contextClass); (3)

        wac.setServletContext(servletContext);

        // configLocation =/WEB-INF/applicationContext-dudu.xml

        String configLocation = servletContext.getInitParameter(CONFIG_LOCATION_PARAM);

        wac.setConfigLocations(StringUtils.tokenizeToStringArray(configLocation,

                    ConfigurableWebApplicationContext.CONFIG_LOCATION_DELIMITERS));

        //简单中隐藏复杂

        wac.refresh();(4)

        return wac;

}

}

 

(3注)

return instantiateClass(clazz.getDeclaredConstructor((Class[]) null), null);

//值得学习的地方

★ public abstract class BeanUtils {

    public static Object instantiateClass(Constructor ctor, Object[] args) throws

BeanInstantiationException {

        if (!Modifier.isPublic(ctor.getModifiers()) ||

                    !Modifier.isPublic(ctor.getDeclaringClass().getModifiers())) {

                ctor.setAccessible(true);

            }

        return ctor.newInstance(args);

    }

}

/*****************段落2********************/

☆      起舞（处理beanDefinition和bean）

★      public abstract class AbstractRefreshableWebApplicationContext extends

AbstractRefreshableApplicationContext implements ConfigurableWebApplicationContext,

ThemeSource {

//模版模式 （4注）

        public void refresh() throws BeansException {

            super.refresh(); (5)

        }

     protected final void refreshBeanFactory() throws BeansException {(6注)

        DefaultListableBeanFactory beanFactory = createBeanFactory();

        loadBeanDefinitions(beanFactory);

       

        //ApplicationContext包装BeanFactory

this.beanFactory = beanFactory;

     }

    }

(5注)

★ public abstract class AbstractApplicationContext extends DefaultResourceLoader

        implements ConfigurableApplicationContext, DisposableBean {

    //真正的重头戏都在这里面了

    public void refresh() throws BeansException, IllegalStateException {

        //调用的是子类AbstractRefreshableWebApplicationContext中的同名方法

//建立DefaultListableBeanFactory对象

        //从配置文件中取得bean信息，转变未BeanDefinition对象，保存在beanFactory

        //的beanDefinition  Names和beanDefinitionMap中

        //具体过程参加“Inside-springframework-bean-definition”

        refreshBeanFactory();(6)

        //查找类型为org.springframework.beans.factory.

//config.BeanPostProcessor的bean，并创建之。

 

（7：参见Inside-springframework-Loader-registerBeanPostProcessors）

//将类型为BeanPostProcessor的bean实例化并保存在beanFactory的beanPocessors

//该类型的bean是Spring中的AopProxyFactory类型

registerBeanPostProcessors();  

 

// 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 singletons this late to allow them to access the message source.

beanFactory.preInstantiateSingletons();

 

// Last step: publish corresponding event.

publishEvent(new ContextRefreshedEvent(this));

    }