1.SpringMvc 中核心Servlet的继承结构图

  

2.HttpServletBean   

public abstract class HttpServletBean extends HttpServlet		implements EnvironmentCapable, EnvironmentAware {   public final void init() throws ServletException {		if (logger.isDebugEnabled()) {			logger.debug("Initializing servlet '" + getServletName() + "'");		}		// Set bean properties from init parameters.		try {			PropertyValues pvs = new ServletConfigPropertyValues(getServletConfig(), this.requiredProperties);			BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);			ResourceLoader resourceLoader = new ServletContextResourceLoader(getServletContext());			bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, getEnvironment()));			initBeanWrapper(bw);			bw.setPropertyValues(pvs, true);		}		catch (BeansException ex) {			logger.error("Failed to set bean properties on servlet '" + getServletName() + "'", ex);			throw ex;		}		// Let subclasses do whatever initialization they like.		initServletBean();		if (logger.isDebugEnabled()) {			logger.debug("Servlet '" + getServletName() + "' configured successfully");		}	}}

3. FrameworkServlet

   

public abstract class FrameworkServlet extends HttpServletBean implements ApplicationContextAware {    protected final void initServletBean() throws ServletException {		getServletContext().log("Initializing Spring FrameworkServlet '" + getServletName() + "'");		if (this.logger.isInfoEnabled()) {			this.logger.info("FrameworkServlet '" + getServletName() + "': initialization started");		}		long startTime = System.currentTimeMillis();		try {
     　　　　　　　　　　　　　　//初始化webApplication			this.webApplicationContext = initWebApplicationContext();  　　　　　　　　　　　　　　//初始化 frameworkServlet			initFrameworkServlet();		}		catch (ServletException ex) {			this.logger.error("Context initialization failed", ex);			throw ex;		}		catch (RuntimeException ex) {			this.logger.error("Context initialization failed", ex);			throw ex;		}		if (this.logger.isInfoEnabled()) {			long elapsedTime = System.currentTimeMillis() - startTime;			this.logger.info("FrameworkServlet '" + getServletName() + "': initialization completed in " +					elapsedTime + " ms");		}	}     }

　初始化 webApplication

protected WebApplicationContext initWebApplicationContext() {		WebApplicationContext rootContext =				WebApplicationContextUtils.getWebApplicationContext(getServletContext());		WebApplicationContext wac = null;		if (this.webApplicationContext != null) {			// A context instance was injected at construction time -> use it			wac = this.webApplicationContext;			if (wac instanceof ConfigurableWebApplicationContext) {				ConfigurableWebApplicationContext cwac = (ConfigurableWebApplicationContext) wac;				if (!cwac.isActive()) {					// The context has not yet been refreshed -> provide services such as					// setting the parent context, setting the application context id, etc					if (cwac.getParent() == null) {						// The context instance was injected without an explicit parent -> set						// the root application context (if any; may be null) as the parent						cwac.setParent(rootContext);					}					configureAndRefreshWebApplicationContext(cwac);				}			}		}		if (wac == null) {			// No context instance was injected at construction time -> see if one			// has been registered in the servlet context. If one exists, it is assumed			// that the parent context (if any) has already been set and that the			// user has performed any initialization such as setting the context id			wac = findWebApplicationContext();		}		if (wac == null) {			// No context instance is defined for this servlet -> create a local one			wac = createWebApplicationContext(rootContext);		}		if (!this.refreshEventReceived) {			// Either the context is not a ConfigurableApplicationContext with refresh			// support or the context injected at construction time had already been			// refreshed -> trigger initial onRefresh manually here.			onRefresh(wac);		}		if (this.publishContext) {			// Publish the context as a servlet context attribute.			String attrName = getServletContextAttributeName();			getServletContext().setAttribute(attrName, wac);			if (this.logger.isDebugEnabled()) {				this.logger.debug("Published WebApplicationContext of servlet '" + getServletName() +						"' as ServletContext attribute with name [" + attrName + "]");			}		}		return wac;	}

　主要做了三件事

     1.获取spring的根容器rootContext

　　2.设置webapplicationContext 并根据情况调用onRefresh

　　3.将webApplicationContext 设置到 ServletContext

4.DispatcherServlet

public class DispatcherServlet extends FrameworkServlet {    protected void onRefresh(ApplicationContext context) {		initStrategies(context);	}       	protected void initStrategies(ApplicationContext context) {		initMultipartResolver(context);		initLocaleResolver(context);		initThemeResolver(context);		initHandlerMappings(context);		initHandlerAdapters(context);		initHandlerExceptionResolvers(context);		initRequestToViewNameTranslator(context);		initViewResolvers(context);		initFlashMapManager(context);	}}