tomcat启动DispatcherServlet默认加载的ViewResolver只有org.springframework.web.servlet.view.InternalResourceViewResolver和自定义HandlerExceptionResolver。
ViewResolver里面只有一个方法resolveViewName(String viewName, Locale locale),按名称解析给定的视图。
DispatcherServlet在doDispatch(HttpServletRequest request, HttpServletResponse response)方法中调用processDispatchResult(HttpServletRequest request, HttpServletResponse response, @Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv, @Nullable Exception exception)方法处理程序调用结果,
当ModelAndView存在且没有被清除时,调用read(ModelAndView mv, HttpServletRequest request, HttpServletResponse response)方法,
如果ModelAndView的视图名称不为空时,调用resolveViewName(String viewName, @Nullable Map<String, Object> model, Locale locale, HttpServletRequest request)方法解析视图名称。
resolveViewName方法先去判断是否有缓存如果有缓存,那就取缓存里面的View,如果没有,则创建一个新的View。
创建View流程如下:
protected View createView(String viewName, Locale locale) throws Exception {
return loadView(viewName, locale);
}
protected View loadView(String viewName, Locale locale) throws Exception {
AbstractUrlBasedView view = buildView(viewName);
View result = applyLifecycleMethods(viewName, view);
return (view.checkResource(locale) ? result : null);
}
protected AbstractUrlBasedView buildView(String viewName) throws Exception {
Class<?> viewClass = getViewClass();
Assert.state(viewClass != null, "No view class");
AbstractUrlBasedView view = (AbstractUrlBasedView) BeanUtils.instantiateClass(viewClass);
view.setUrl(getPrefix() + viewName + getSuffix());
String contentType = getContentType();
if (contentType != null) {
view.setContentType(contentType);
}
view.setRequestContextAttribute(getRequestContextAttribute());
view.setAttributesMap(getAttributesMap());
Boolean exposePathVariables = getExposePathVariables();
if (exposePathVariables != null) {
view.setExposePathVariables(exposePathVariables);
}
Boolean exposeContextBeansAsAttributes = getExposeContextBeansAsAttributes();
if (exposeContextBeansAsAttributes != null) {
view.setExposeContextBeansAsAttributes(exposeContextBeansAsAttributes);
}
String[] exposedContextBeanNames = getExposedContextBeanNames();
if (exposedContextBeanNames != null) {
view.setExposedContextBeanNames(exposedContextBeanNames);
}
return view;
}