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AbstractCachingViewResolver allows for caching unresolved view names ("cacheUnresolved"=true; SPR-8524)

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This commit is contained in:
Juergen Hoeller
2011-11-28 22:35:48 +00:00
parent 8a43dd172c
commit d0032f43c7
1 changed files with 33 additions and 5 deletions
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38
org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/view/AbstractCachingViewResolver.java
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@@ -1,5 +1,5 @@
/* /*
* Copyright 2002-2009 the original author or authors. * Copyright 2002-2011 the original author or authors.
* *
* Licensed under the Apache License, Version 2.0 (the "License"); * Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License. * you may not use this file except in compliance with the License.
@@ -42,6 +42,9 @@ public abstract class AbstractCachingViewResolver extends WebApplicationObjectSu
/** Whether we should cache views, once resolved */ /** Whether we should cache views, once resolved */
private boolean cache = true; private boolean cache = true;
/** Whether we should refrain from resolving views again if unresolved once */
private boolean cacheUnresolved = false;
/** Map from view key to View instance */ /** Map from view key to View instance */
private final Map<Object, View> viewCache = new HashMap<Object, View>(); private final Map<Object, View> viewCache = new HashMap<Object, View>();
@@ -63,6 +66,29 @@ public abstract class AbstractCachingViewResolver extends WebApplicationObjectSu
return this.cache; return this.cache;
} }
/**
* Whether a view name once resolved to {@code null} should be cached and
* automatically resolved to {@code null} subsequently.
* <p>Default is "false": unresolved view names are NOT being cached.
* Note that this flag only applies if the general {@link #setCache "cache"}
* flag is kept at its default of "true" as well.
* <p>Of specific interest is the ability for some AbstractUrlBasedView
* implementations (FreeMarker, Velocity, Tiles) to check if an underlying
* resource exists via {@link 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", one check is made only.
*/
public void setCacheUnresolved(boolean cacheUnresolved) {
this.cacheUnresolved = cacheUnresolved;
}
/**
* Return if caching of unresolved views is enabled.
*/
public boolean isCacheUnresolved() {
return this.cacheUnresolved;
}
public View resolveViewName(String viewName, Locale locale) throws Exception { public View resolveViewName(String viewName, Locale locale) throws Exception {
if (!isCache()) { if (!isCache()) {
@@ -72,12 +98,14 @@ public abstract class AbstractCachingViewResolver extends WebApplicationObjectSu
Object cacheKey = getCacheKey(viewName, locale); Object cacheKey = getCacheKey(viewName, locale);
synchronized (this.viewCache) { synchronized (this.viewCache) {
View view = this.viewCache.get(cacheKey); View view = this.viewCache.get(cacheKey);
if (view == null) { if (view == null && (!this.cacheUnresolved || !this.viewCache.containsKey(cacheKey))) {
// Ask the subclass to create the View object. // Ask the subclass to create the View object.
view = createView(viewName, locale); view = createView(viewName, locale);
this.viewCache.put(cacheKey, view); if (view != null || this.cacheUnresolved) {
if (logger.isTraceEnabled()) { this.viewCache.put(cacheKey, view);
logger.trace("Cached view [" + cacheKey + "]"); if (logger.isTraceEnabled()) {
logger.trace("Cached view [" + cacheKey + "]");
}
} }
} }
return view; return view;