org.springframework.web.servlet.view: abstract public class: AbstractCachingViewResolver

org.springframework.web.servlet.view
abstract public class: AbstractCachingViewResolver [javadoc | source]

java.lang.Object
   org.springframework.context.support.ApplicationObjectSupport
      org.springframework.web.context.support.WebApplicationObjectSupport
         org.springframework.web.servlet.view.AbstractCachingViewResolver

All Implemented Interfaces:
ViewResolver, ServletContextAware, ApplicationContextAware

Direct Known Subclasses:
JasperReportsViewResolver, VelocityLayoutViewResolver, InternalResourceViewResolver, UrlBasedViewResolver, ResourceBundleViewResolver, AbstractTemplateViewResolver, VelocityViewResolver, XsltViewResolver, XmlViewResolver, FreeMarkerViewResolver

Convenient base class for org.springframework.web.servlet.ViewResolver implementations. Caches org.springframework.web.servlet.View objects once resolved: This means that view resolution won't be a performance problem, no matter how costly initial view retrieval is.

Subclasses need to implement the #loadView template method, building the View object for a specific view name and locale.

Also see:

loadView

author: Rod - Johnson

author: Juergen - Hoeller

Fields inherited from org.springframework.context.support.ApplicationObjectSupport:
logger

Method from org.springframework.web.servlet.view.AbstractCachingViewResolver Summary:
clearCache, createView, getCacheKey, isCache, loadView, removeFromCache, resolveViewName, setCache

Methods from org.springframework.web.context.support.WebApplicationObjectSupport:
getServletContext, getTempDir, getWebApplicationContext, initApplicationContext, initServletContext, isContextRequired, setServletContext

Methods from org.springframework.context.support.ApplicationObjectSupport:
getApplicationContext, getMessageSourceAccessor, initApplicationContext, initApplicationContext, isContextRequired, requiredContextClass, setApplicationContext

Methods from java.lang.Object:
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from org.springframework.web.servlet.view.AbstractCachingViewResolver Detail:
public void clearCache() { logger.debug("Clearing entire view cache"); synchronized (this.viewCache) { this.viewCache.clear(); } } Clear the entire view cache, removing all cached view objects. Subsequent resolve calls will lead to recreation of demanded view objects.
protected View createView(String viewName, Locale locale) throws Exception { return loadView(viewName, locale); } Create the actual View object. The default implementation delegates to #loadView . This can be overridden to resolve certain view names in a special fashion, before delegating to the actual `loadView` implementation provided by the subclass.
protected Object getCacheKey(String viewName, Locale locale) { return viewName + "_" + locale; } Return the cache key for the given view name and the given locale. Default is a String consisting of view name and locale suffix. Can be overridden in subclasses. Needs to respect the locale in general, as a different locale can lead to a different view resource.
public boolean isCache() { return this.cache; } Return if caching is enabled.
abstract protected View loadView(String viewName, Locale locale) throws Exception Subclasses must implement this method, building a View object for the specified view. The returned View objects will be cached by this ViewResolver base class. Subclasses are not forced to support internationalization: A subclass that does not may simply ignore the locale parameter.
public void removeFromCache(String viewName, Locale locale) { if (!this.cache) { logger.warn("View caching is SWITCHED OFF -- removal not necessary"); } else { Object cacheKey = getCacheKey(viewName, locale); Object cachedView = null; synchronized (this.viewCache) { cachedView = this.viewCache.remove(cacheKey); } if (cachedView == null) { // Some debug output might be useful... if (logger.isDebugEnabled()) { logger.debug("No cached instance for view '" + cacheKey + "' was found"); } } else { if (logger.isDebugEnabled()) { logger.debug("Cache for view " + cacheKey + " has been cleared"); } } } } Provides functionality to clear the cache for a certain view. This can be handy in case developer are able to modify views (e.g. Velocity templates) at runtime after which you'd need to clear the cache for the specified view.
public View resolveViewName(String viewName, Locale locale) throws Exception { if (!isCache()) { logger.warn("View caching is SWITCHED OFF -- DEVELOPMENT SETTING ONLY: This can severely impair performance"); return createView(viewName, locale); } else { Object cacheKey = getCacheKey(viewName, locale); synchronized (this.viewCache) { View view = (View) this.viewCache.get(cacheKey); if (view == null) { // Ask the subclass to create the View object. view = createView(viewName, locale); this.viewCache.put(cacheKey, view); if (logger.isDebugEnabled()) { logger.debug("Cached view [" + cacheKey + "]"); } } return view; } } }
public void setCache(boolean cache) { this.cache = cache; } Enable or disable caching. Default is "true": caching is enabled. Disable this only for debugging and development. Warning: Disabling caching can severely impact performance.

Method from org.springframework.web.servlet.view.AbstractCachingViewResolver Detail:

 public  void clearCache() {
		logger.debug("Clearing entire view cache");
		synchronized (this.viewCache) {
			this.viewCache.clear();
		}
}

Clear the entire view cache, removing all cached view objects. Subsequent resolve calls will lead to recreation of demanded view objects.

 protected View createView(String viewName,
    Locale locale) throws Exception {
		return loadView(viewName, locale);
}

The default implementation delegates to #loadView . This can be overridden to resolve certain view names in a special fashion, before delegating to the actual loadView implementation provided by the subclass.

 protected Object getCacheKey(String viewName,
    Locale locale) {
		return viewName + "_" + locale;
}

Default is a String consisting of view name and locale suffix. Can be overridden in subclasses.

Needs to respect the locale in general, as a different locale can lead to a different view resource.

 public boolean isCache() {
		return this.cache;
}

Return if caching is enabled.

 abstract protected View loadView(String viewName,
    Locale locale) throws ExceptionSubclasses must implement this method, building a View object
for the specified view. The returned View objects will be
cached by this ViewResolver base class.
Subclasses are not forced to support internationalization:
A subclass that does not may simply ignore the locale parameter.

 public  void removeFromCache(String viewName,
    Locale locale) {
		if (!this.cache) {
			logger.warn("View caching is SWITCHED OFF -- removal not necessary");			
		}
		else {
			Object cacheKey = getCacheKey(viewName, locale);
			Object cachedView = null;
			synchronized (this.viewCache) {
				cachedView = this.viewCache.remove(cacheKey);
			}
			if (cachedView == null) {
				// Some debug output might be useful...
				if (logger.isDebugEnabled()) {
					logger.debug("No cached instance for view '" + cacheKey + "' was found");
				}
			} 
			else {
				if (logger.isDebugEnabled()) {
					logger.debug("Cache for view " + cacheKey + " has been cleared");
				}
			}
		}
}

This can be handy in case developer are able to modify views (e.g. Velocity templates) at runtime after which you'd need to clear the cache for the specified view.

 public View resolveViewName(String viewName,
    Locale locale) throws Exception {
		if (!isCache()) {
			logger.warn("View caching is SWITCHED OFF -- DEVELOPMENT SETTING ONLY: This can severely impair performance");
			return createView(viewName, locale);
		}
		else {
			Object cacheKey = getCacheKey(viewName, locale);
			synchronized (this.viewCache) {
				View view = (View) this.viewCache.get(cacheKey);
				if (view == null) {
					// Ask the subclass to create the View object.
					view = createView(viewName, locale);
					this.viewCache.put(cacheKey, view);
					if (logger.isDebugEnabled()) {
						logger.debug("Cached view [" + cacheKey + "]");
					}
				}
				return view;
			}
		}
}

 public  void setCache(boolean cache) {
	                        	 
		this.cache = cache;
}

Default is "true": caching is enabled. Disable this only for debugging and development.

Warning: Disabling caching can severely impact performance.