SpringMVC容器初始化

核心DispatcherServlet的继承关系

HttpServlet?HttpServletBean?FramewokServlet?DispatcherServlet

当只使用DispatcherServlet创建spring容器时，步骤如下：

在FrameworkServlet的initWebApplicationContext()方法中创建spring容器。同时在该类中定义内部类ContextRefreshListener实现ApplicationListener接口

private class ContextRefreshListener implements ApplicationListener<ContextRefreshedEvent> {

     public void onApplicationEvent(ContextRefreshedEvent event) {

         FrameworkServlet.this.onApplicationEvent(event);

     }

}

onApplicationEvent()方法通过Spring容器的publishEvent()方法来触发，从而调用FrameworkServlet.this.onApplicationEvent(event)方法中定义的onRefresh(event.getApplicationContext())方法来初始化springmvc需要的组件

protected void initStrategies(ApplicationContext context) {

     initMultipartResolver(context);

     initLocaleResolver(context);

     initThemeResolver(context);

     initHandlerMappings(context);

     initHandlerAdapters(context);

     initHandlerExceptionResolvers(context);

     initRequestToViewNameTranslator(context);

     initViewResolvers(context);

}

        那么在什么地方调用publishEvent()方法的呢，从initWebApplicationContext()的部分代码中可以看到

protected WebApplicationContext initWebApplicationContext() {

     WebApplicationContext wac = findWebApplicationContext();

     if (wac == null) {

         // No fixed context defined for this servlet - create a local one.

         WebApplicationContext parent =

    //当wac为空时，创建上下文，跟踪createWebApplicationContext方法，可以看到该//方法调用refresh方法，refresh方法中又调用finishRefresh(),在finishRefresh方法中

//调用publishEvent()方法从而触发ContextRefreshListener监听的事件

WebApplicationContextUtils.getWebApplicationContext(getServletContext());

wac = createWebApplicationContext(parent);

     }

     if (!this.refreshEventReceived) {

     //当wac不为空时，手动调用onRefresh()方法初始化springmvc的组件

         onRefresh(wac);

     }

            下面演示一个ApplicationLIstener监听器的例子

MyListener(实现ApplicationListener接口)

import org.springframework.context.ApplicationListener;

import org.springframework.stereotype.Component;

import event.MyEvent;

@Component

public class MyListener implements ApplicationListener<MyEvent> {

     public MyListener(){

     System.out.println("myListener构造方法");

     }

@Override

public void onApplicationEvent(MyEvent event) {

     // TODO Auto-generated method stub

     System.err.println("myEvent事件触发了:"+event.getName());

}

}

MyEvent(继承ApplicationEvent类)

import org.springframework.context.ApplicationEvent;

public class MyEvent extends ApplicationEvent  {

/**

 * @param source

 */

public MyEvent(Object source) {

     super(source);

     // TODO Auto-generated constructor stub

}

private String name="Lee";

public String getName() {

     return name;

}

public void setName(String name) {

     this.name = name;

}

TestListener(实现InitializingBean和ApplicationContextAware接口，实现InitializingBean接口的Bean其afterPropertiesSet方法在其初始化时会被执行,实现ApplicationContextAware接口可以获得容器对象)

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.InitializingBean;

import org.springframework.context.ApplicationContext;

import org.springframework.context.ApplicationContextAware;

import org.springframework.stereotype.Component;

import event.MyEvent;

@Component

public class TestListener implements InitializingBean,ApplicationContextAware{

private ApplicationContext context;

@Override

public void afterPropertiesSet() throws Exception {

     // TODO Auto-generated method stub

     System.out.println("afterPropertiesSet方法");

     System.out.println(this.context);

     this.context.publishEvent(new MyEvent(new Object()));

}

@Override

public void setApplicationContext(ApplicationContext applicationContext)

         throws BeansException {

     // TODO Auto-generated method stub

     this.context = applicationContext;

}

}