org.omnifaces.component.output

Class Cache

java.lang.Object

javax.faces.component.UIComponent

javax.faces.component.UIComponentBase

org.omnifaces.component.output.OutputFamily

org.omnifaces.component.output.Cache

All Implemented Interfaces:

EventListener, PartialStateHolder, StateHolder, TransientStateHolder, ComponentSystemEventListener, FacesListener, SystemEventListenerHolder

public class Cache
extends OutputFamily

The <o:cache> component allows to cache a fragment of rendered markup. The first request for a page that has this component on it will cause this markup to be put into the cache. Then for subsequent requests the cached content is used directly and none of the components, backing beans and services that were used to generate this content in the first place will be consulted.

Caching can take place in application scope, or in session scope. For individual fragments a time can be specified for which the cached content is valid. After this time is elapsed, the very first request to the page containing the cache component in question will cause new content to be rendered and put into the cache. A default time can be set per scope in web.xml.

For each scope a maximum capacity can be set. If the capacity for that scope is exceeded, an element will be removed following a least recently used policy (LRU).

Via a cache provider mechanism an alternative cache implementation can be configured in web.xml. The default cache is based on https://github.com/ben-manes/concurrentlinkedhashmap.

Setting a custom caching provider

A custom caching provider can be set by using the org.omnifaces.CACHE_PROVIDER context parameter in web.xml to point to an implementation of org.omnifaces.component.output.cache.CacheProvider. For example:

 <context-param>
     <param-name>org.omnifaces.CACHE_PROVIDER</param-name>
     <param-value>com.example.MyProvider</param-value>
 </context-param>
 

The default provider, org.omnifaces.component.output.cache.DefaultCacheProvider can be used as an example.

Global settings

For the default provider, the maximum capacity and the default time to live can be specified for the supported scopes "session" and "application". If the maximum capacity is reached, an entry will be evicted following a least recently used policy. The default time to live specifies for how long entries are considered to be valid. A value for the time attribute on this component will override this global default time to live. The following context parameters can be used in web.xml:

org.omnifaces.CACHE_SETTING_APPLICATION_MAX_CAPACITY	Sets the maximum number of elements that will be stored per web module (application scope). Default: no limit
org.omnifaces.CACHE_SETTING_SESSION_MAX_CAPACITY	Sets the maximum number of elements that will be stored per session. Default: no limit.
org.omnifaces.CACHE_SETTING_APPLICATION_TTL	Sets the maximum amount of time in seconds that cached content is valid for the application scope. Can be overriden by individal cache components. Default: no limit.
org.omnifaces.CACHE_SETTING_SESSION_TTL	Sets the maximum amount of time in seconds that cached content is valid for the session scope. Can be overriden by individal cache components. Default: no limit.
org.omnifaces.CACHE_INSTALL_BUFFER_FILTER	Boolean that when true installs a Servlet Filter (Servlet 3.0+ only) that works in conjunction with the useBuffer attribute of the Cache component to enable an alternative way to grab the content that needs to be cached. This is a convenience setting that is a short-cut for installing the org.omnifaces.servlet.BufferedHttpServletResponse filter manually. If more finegrained control is needed regarding which place in the filter chain the filter appears and which resources it exactly filters, this setting should not be used and the mentioned filter should be manually configured. Default: false.

Since:

1.1

Author:

Arjan Tijms

See Also:

Cache, CacheEntry, CacheFactory, CacheInitializer, CacheInstancePerScopeProvider, CacheProvider, DefaultCache, DefaultCacheProvider, TimeToLiveCache, CacheValue, CachingValueExpression, OnDemandResponseBufferFilter, BufferedHttpServletResponse, HttpServletResponseOutputWrapper, ResettableBuffer, ResettableBufferedOutputStream, ResettableBufferedWriter, OutputFamily

Field Summary

Fields

Modifier and Type	Field and Description
static String	COMPONENT_TYPE
static String	DEFAULT_SCOPE
static String	END_CONTENT_MARKER
static String	START_CONTENT_MARKER
static String	VALUE_SET

Fields inherited from class org.omnifaces.component.output.OutputFamily

COMPONENT_FAMILY

Fields inherited from class javax.faces.component.UIComponent

ATTRS_WITH_DECLARED_DEFAULT_VALUES, BEANINFO_KEY, bindings, COMPOSITE_COMPONENT_TYPE_KEY, COMPOSITE_FACET_NAME, CURRENT_COMPONENT, CURRENT_COMPOSITE_COMPONENT, FACETS_KEY, HONOR_CURRENT_COMPONENT_ATTRIBUTES_PARAM_NAME, VIEW_LOCATION_KEY

Constructor Summary

Constructors

Constructor and Description
Cache()

Method Summary

Modifier and Type	Method and Description
void	encodeChildren(FacesContext context)
Serializable	getCacheAttribute(FacesContext context, String name) Gets a named attribute associated with the main cache entry this component is using to store the rendering of its child components.
String	getKey()
String	getScope()
Integer	getTime()
boolean	isDisabled() Returns whether this cache is disabled.
boolean	isReset()
boolean	isUseBuffer()
protected boolean	isVisitable(VisitContext visitContext)
void	setCacheAttribute(FacesContext context, String name, Serializable value) Sets a named attribute associated with the main cache entry this component is using to store the rendering of its child components.
void	setDisabled(boolean disabledValue) Sets whether this cache is disabled.
void	setKey(String keyValue)
void	setReset(boolean resetValue)
void	setScope(String scopeValue)
void	setTime(Integer timeValue)
void	setUseBuffer(boolean useBufferValue)

Methods inherited from class org.omnifaces.component.output.OutputFamily

getFamily, getRendersChildren

Methods inherited from class javax.faces.component.UIComponentBase

addClientBehavior, addFacesListener, broadcast, clearInitialState, decode, encodeBegin, encodeEnd, findComponent, getAttributes, getChildCount, getChildren, getClientBehaviors, getClientId, getDefaultEventName, getEventNames, getFacesContext, getFacesListeners, getFacet, getFacetCount, getFacets, getFacetsAndChildren, getId, getListenersForEventClass, getParent, getPassThroughAttributes, getRenderer, getRendererType, getValueBinding, invokeOnComponent, isRendered, isTransient, markInitialState, processDecodes, processRestoreState, processSaveState, processUpdates, processValidators, queueEvent, removeFacesListener, restoreAttachedState, restoreState, saveAttachedState, saveState, setId, setParent, setRendered, setRendererType, setTransient, setValueBinding, subscribeToEvent, unsubscribeFromEvent

Methods inherited from class javax.faces.component.UIComponent

encodeAll, getClientId, getCompositeComponentParent, getContainerClientId, getCurrentComponent, getCurrentCompositeComponent, getNamingContainer, getPassThroughAttributes, getResourceBundleMap, getStateHelper, getStateHelper, getTransientStateHelper, getTransientStateHelper, getValueExpression, initialStateMarked, isCompositeComponent, isInView, popComponentFromEL, processEvent, pushComponentToEL, restoreTransientState, saveTransientState, setInView, setValueExpression, visitTree

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

COMPONENT_TYPE

public static final String COMPONENT_TYPE

See Also:

Constant Field Values

VALUE_SET

public static final String VALUE_SET

See Also:

Constant Field Values

DEFAULT_SCOPE

public static final String DEFAULT_SCOPE

See Also:

Constant Field Values

START_CONTENT_MARKER

public static final String START_CONTENT_MARKER

See Also:

Constant Field Values

END_CONTENT_MARKER

public static final String END_CONTENT_MARKER

See Also:

Constant Field Values

Constructor Detail

Cache

public Cache()

Method Detail

encodeChildren

public void encodeChildren(FacesContext context)
                    throws IOException

Overrides:

encodeChildren in class UIComponentBase

Throws:

IOException

getCacheAttribute

public Serializable getCacheAttribute(FacesContext context,
                                      String name)

Gets a named attribute associated with the main cache entry this component is using to store the rendering of its child components.

Parameters:

context - the current FacesContext

name - name of the attribute to retrieve a value for

Returns:

value associated with the named attribute

Since:

1.2

setCacheAttribute

public void setCacheAttribute(FacesContext context,
                              String name,
                              Serializable value)

Sets a named attribute associated with the main cache entry this component is using to store the rendering of its child components.

Parameters:

context - the current FacesContext

name - name of the attribute under which the value is stored

value - the value that is to be stored

Since:

1.2

isVisitable

protected boolean isVisitable(VisitContext visitContext)

Overrides:

isVisitable in class UIComponent

getKey

public String getKey()

setKey

public void setKey(String keyValue)

getScope

public String getScope()

setScope

public void setScope(String scopeValue)

getTime

public Integer getTime()

setTime

public void setTime(Integer timeValue)

isUseBuffer

public boolean isUseBuffer()

setUseBuffer

public void setUseBuffer(boolean useBufferValue)

isReset

public boolean isReset()

setReset

public void setReset(boolean resetValue)

isDisabled

public boolean isDisabled()

Returns whether this cache is disabled.

Returns:

Whether this cache is disabled.

Since:

1.8

setDisabled

public void setDisabled(boolean disabledValue)

Sets whether this cache is disabled.

Parameters:

disabledValue - Whether this cache is disabled.

Since:

1.8