Package org.springframework.web.servlet.view

Class AbstractCachingViewResolver

java.lang.Object
org.springframework.context.support.ApplicationObjectSupport
org.springframework.web.context.support.WebApplicationObjectSupport
org.springframework.web.servlet.view.AbstractCachingViewResolver
All Implemented Interfaces:
Aware, ApplicationContextAware, ServletContextAware, ViewResolver
Direct Known Subclasses:
ResourceBundleViewResolver, UrlBasedViewResolver, XmlViewResolver
public abstract class AbstractCachingViewResolver extends WebApplicationObjectSupport implements ViewResolver
Convenient base class for ViewResolver implementations. Caches 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(java.lang.String, java.util.Locale) template method, building the View object for a specific view name and locale.

Author:
Rod Johnson, Juergen Hoeller
See Also:

  • Field Details

    • DEFAULT_CACHE_LIMIT

      public static final int DEFAULT_CACHE_LIMIT
      Default maximum number of entries for the view cache: 1024.
      See Also:

  • Constructor Details

    • AbstractCachingViewResolver

      public AbstractCachingViewResolver()

  • Method Details

    • setCacheLimit

      public void setCacheLimit(int cacheLimit)
      Specify the maximum number of entries for the view cache. Default is 1024.

    • getCacheLimit

      public int getCacheLimit()
      Return the maximum number of entries for the view cache.

    • setCache

      public void setCache(boolean cache)
      Enable or disable caching.

      This is equivalent to setting the "cacheLimit" property to the default limit (1024) or to 0, respectively.

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

    • isCache

      public boolean isCache()
      Return if caching is enabled.

    • setCacheUnresolved

      public void setCacheUnresolved(boolean cacheUnresolved)
      Whether a view name once resolved to null should be cached and automatically resolved to null subsequently.

      Default is "true": unresolved view names are cached. Note that this flag only applies if the general "cache" flag is kept at its default of "true" as well.

      Of specific interest is the ability for some AbstractUrlBasedView implementations (e.g., FreeMarker) to check if an underlying resource exists via AbstractUrlBasedView.checkResource(Locale). With this flag set to "false", an underlying resource that re-appears is noticed and used. With the flag set to "true", only one check is made.

    • isCacheUnresolved

      public boolean isCacheUnresolved()
      Return if caching of unresolved views is enabled.

    • setCacheFilter

      public void setCacheFilter(AbstractCachingViewResolver.CacheFilter cacheFilter)
      Set the filter that determines if view should be cached.

      Default behaviour is to cache all views.

      Since:
      5.2

    • getCacheFilter

      public AbstractCachingViewResolver.CacheFilter getCacheFilter()
      Return filter function that determines if view should be cached.
      Since:
      5.2

    • resolveViewName

      @Nullable public View resolveViewName(String viewName, Locale locale) throws Exception
      Description copied from interface: ViewResolver
      Resolve the given view by name.

      Note: To allow for ViewResolver chaining, a ViewResolver should return null if a view with the given name is not defined in it. However, this is not required: Some ViewResolvers will always attempt to build View objects with the given name, unable to return null (rather throwing an exception when View creation failed).

      Specified by:
      resolveViewName in interface ViewResolver
      Parameters:
      viewName - name of the view to resolve
      locale - the Locale in which to resolve the view. ViewResolvers that support internationalization should respect this.
      Returns:
      the View object, or null if not found (optional, to allow for ViewResolver chaining)
      Throws:
      Exception - if the view cannot be resolved (typically in case of problems creating an actual View object)

    • getCacheKey

      protected Object getCacheKey(String viewName, Locale 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.

    • removeFromCache

      public void removeFromCache(String viewName, Locale locale)
      Provides functionality to clear the cache for a certain view.

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

      Parameters:
      viewName - the view name for which the cached view object (if any) needs to be removed
      locale - the locale for which the view object should be removed

    • clearCache

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

    • createView

      @Nullable protected View createView(String viewName, Locale locale) throws Exception
      Create the actual View object.

      The default implementation delegates to loadView(java.lang.String, java.util.Locale). This can be overridden to resolve certain view names in a special fashion, before delegating to the actual loadView implementation provided by the subclass.

      Parameters:
      viewName - the name of the view to retrieve
      locale - the Locale to retrieve the view for
      Returns:
      the View instance, or null if not found (optional, to allow for ViewResolver chaining)
      Throws:
      Exception - if the view couldn't be resolved
      See Also:

    • loadView

      @Nullable protected abstract 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.

      Parameters:
      viewName - the name of the view to retrieve
      locale - the Locale to retrieve the view for
      Returns:
      the View instance, or null if not found (optional, to allow for ViewResolver chaining)
      Throws:
      Exception - if the view couldn't be resolved
      See Also: