springmvc中的resolveView（视图解析器）

视图解析器接口只有一个方法，就是根据名称解析出视图信息（一个视图对象View）

采用的是模板模式  抽象模板类 AbstractCachingViewResolver  主要处理缓存，如果视图对象在缓存中有，则从缓存中取，如果没有则创建

public View resolveViewName(String viewName, Locale locale) throws Exception {

if (!isCache()) {

return createView(viewName, locale);

}

else {

Object cacheKey = getCacheKey(viewName, locale);

View view = this.viewAccessCache.get(cacheKey);

if (view == null) {

synchronized (this.viewCreationCache) {

view = this.viewCreationCache.get(cacheKey);

if (view == null) {

// Ask the subclass to create the View object.

view = createView(viewName, locale);

if (view == null && this.cacheUnresolved) {

view = UNRESOLVED_VIEW;

}

if (view != null) {

this.viewAccessCache.put(cacheKey, view);

this.viewCreationCache.put(cacheKey, view);

if (logger.isTraceEnabled()) {

logger.trace("Cached view [" + cacheKey + "]");

}

}

}

}

}

return (view != UNRESOLVED_VIEW ? view : null);

}

}

其中 createView 是抽象方法，在各个子类中去分别实现