/**
* Resource bundle backed message interpolator.
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
* @author Gunnar Morling
*/
public class ResourceBundleMessageInterpolator implements MessageInterpolator {
   // ...

   /**
    * Step 1-3 of message interpolation can be cached. We do this in this map.
    */
   private final Map<LocalisedMessage, String> resolvedMessages = new WeakHashMap<LocalisedMessage, String>();

   /**
    * Flag indicating whether this interpolator should chance some of the interpolation steps.
    */
   private final boolean cacheMessages;

   public ResourceBundleMessageInterpolator() {
      this( null );
   }

   public ResourceBundleMessageInterpolator(ResourceBundleLocator userResourceBundleLocator) {
      this( userResourceBundleLocator, true );
   }

   public ResourceBundleMessageInterpolator(ResourceBundleLocator userResourceBundleLocator, boolean cacheMessages) {

      defaultLocale = Locale.getDefault();

      if ( userResourceBundleLocator == null ) {
         this.userResourceBundleLocator = new PlatformResourceBundleLocator( USER_VALIDATION_MESSAGES );
      }
      else {
         this.userResourceBundleLocator = userResourceBundleLocator;
      }

      this.defaultResourceBundleLocator = new PlatformResourceBundleLocator( DEFAULT_VALIDATION_MESSAGES );
      this.cacheMessages = cacheMessages;
   }

   // ...

   private String interpolateMessage(String message, Map<String, Object> annotationParameters, Locale locale) {
      LocalisedMessage localisedMessage = new LocalisedMessage( message, locale );
      String resolvedMessage = null;

      if ( cacheMessages ) {
         resolvedMessage = resolvedMessages.get( localisedMessage );
      }

                  // ...

      if ( cacheMessages ) {
         resolvedMessages.put( localisedMessage, resolvedMessage );
      }

                  // ...
   }

   // ...
}