org.apache.velocity.context
Class AbstractContext

java.lang.Object
  org.apache.velocity.context.AbstractContext

All Implemented Interfaces:

Serializable, Context, InternalEventContext

Direct Known Subclasses:

VelocityContext

public abstract class AbstractContext
extends Object
implements Context, Serializable

This class is the abstract base class for all conventional Velocity Context implementations. Simply extend this class and implement the abstract routines that access your preferred storage method. Takes care of context chaining. Also handles / enforces policy on null keys and values :

• Null keys and values are accepted and basically dropped.
• If you place an object into the context with a null key, it will be ignored and logged.
• If you try to place a null into the context with any key, it will be dropped and logged.

The default implementation of this for application use is org.apache.velocity.VelocityContext. All thanks to Fedor for the chaining idea.

Version:

$Id: AbstractContext.java 151591 2005-02-06 15:42:19Z wglass $

Author:

Geir Magnusson Jr., Fedor Karpelevitch, Jason van Zyl

See Also:

Serialized Form

Constructor Summary

AbstractContext()
default CTOR

AbstractContext(Context inner)
Chaining constructor accepts a Context argument.

Method Summary

EventCartridge	attachEventCartridge(EventCartridge ec)
boolean	containsKey(Object key) Indicates whether the specified key is in the context.
Object	get(String key) Gets the value corresponding to the provided key from the context.
boolean	getAllowRendering() Checks to see if rendering should be allowed.
Context	getChainedContext() returns innerContext if one is chained
Resource	getCurrentResource() temporary fix to enable #include() to figure out current encoding.
String	getCurrentTemplateName() get the current template name
EventCartridge	getEventCartridge()
Object[]	getKeys() Get all the keys for the values in the context
Object[]	getTemplateNameStack() get the current template name stack
IntrospectionCacheData	icacheGet(Object key) returns an IntrospectionCache Data (@see IntrospectionCacheData) object if exists for the key
void	icachePut(Object key, IntrospectionCacheData o) places an IntrospectionCache Data (@see IntrospectionCacheData) element in the cache for specified key
abstract boolean	internalContainsKey(Object key) Implement to determine if a key is in the storage.
abstract Object	internalGet(String key) Implement to return a value from the context storage.
abstract Object[]	internalGetKeys() Implement to return an object array of key strings from your storage.
abstract Object	internalPut(String key, Object value) Implement to put a value into the context storage.
abstract Object	internalRemove(Object key) I mplement to remove an item from your storage.
void	popCurrentTemplateName() remove the current template name from stack
void	pushCurrentTemplateName(String s) set the current template name on top of stack
Object	put(String key, Object value) Adds a name/value pair to the context.
Object	remove(Object key) Removes the value associated with the specified key from the context.
void	setAllowRendering(boolean v) Set whether rendering is allowed.
void	setCurrentResource(Resource r)

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractContext

public AbstractContext()

default CTOR

AbstractContext

public AbstractContext(Context inner)

Chaining constructor accepts a Context argument. It will relay get() operations into this Context in the even the 'local' get() returns null.

Parameters:

inner - context to be chained

Method Detail

internalGet

public abstract Object internalGet(String key)

Implement to return a value from the context storage.

The implementation of this method is required for proper operation of a Context implementation in general Velocity use.

Parameters:

key - key whose associated value is to be returned

Returns:

object stored in the context

internalPut

public abstract Object internalPut(String key,
                                   Object value)

Implement to put a value into the context storage.

The implementation of this method is required for proper operation of a Context implementation in general Velocity use.

Parameters:

key - key with which to associate the value

value - value to be associated with the key

Returns:

previously stored value if exists, or null

internalContainsKey

public abstract boolean internalContainsKey(Object key)

Implement to determine if a key is in the storage.

Currently, this method is not used internally by the Velocity core.

Parameters:

key - key to test for existance

Returns:

true if found, false if not

internalGetKeys

public abstract Object[] internalGetKeys()

Implement to return an object array of key strings from your storage.

Currently, this method is not used internally by the Velocity core.

Returns:

array of keys

internalRemove

public abstract Object internalRemove(Object key)

I mplement to remove an item from your storage.

Currently, this method is not used internally by the Velocity core.

Parameters:

key - key to remove

Returns:

object removed if exists, else null

put

public Object put(String key,
                  Object value)

Adds a name/value pair to the context.

Specified by:

put in interface Context

Parameters:

key - The name to key the provided value with.

value - The corresponding value.

Returns:

Object that was replaced in the the Context if applicable or null if not.

get

public Object get(String key)

Gets the value corresponding to the provided key from the context. Supports the chaining context mechanism. If the 'local' context doesn't have the value, we try to get it from the chained context.

Specified by:

get in interface Context

Parameters:

key - The name of the desired value.

Returns:

The value corresponding to the provided key or null if the key param is null.

containsKey

public boolean containsKey(Object key)

Indicates whether the specified key is in the context. Provided for debugging purposes.

Specified by:

containsKey in interface Context

Parameters:

key - The key to look for.

Returns:

true if the key is in the context, false if not.

getKeys

public Object[] getKeys()

Get all the keys for the values in the context

Specified by:

getKeys in interface Context

Returns:

Object[] of keys in the Context. Does not return keys in chained context.

remove

public Object remove(Object key)

Removes the value associated with the specified key from the context.

Specified by:

remove in interface Context

Parameters:

key - The name of the value to remove.

Returns:

The value that the key was mapped to, or null if unmapped.

getChainedContext

public Context getChainedContext()

returns innerContext if one is chained

Returns:

Context if chained, null if not

pushCurrentTemplateName

public void pushCurrentTemplateName(String s)

set the current template name on top of stack

Parameters:

s - current template name

popCurrentTemplateName

public void popCurrentTemplateName()

remove the current template name from stack

getCurrentTemplateName

public String getCurrentTemplateName()

get the current template name

Returns:

String current template name

getTemplateNameStack

public Object[] getTemplateNameStack()

get the current template name stack

Returns:

Object[] with the template name stack contents.

icacheGet

public IntrospectionCacheData icacheGet(Object key)

returns an IntrospectionCache Data (@see IntrospectionCacheData) object if exists for the key

Parameters:

key - key to find in cache

Returns:

cache object

icachePut

public void icachePut(Object key,
                      IntrospectionCacheData o)

places an IntrospectionCache Data (@see IntrospectionCacheData) element in the cache for specified key

Parameters:

key - key

o - IntrospectionCacheData object to place in cache

setCurrentResource

public void setCurrentResource(Resource r)

getCurrentResource

public Resource getCurrentResource()

temporary fix to enable #include() to figure out current encoding.

getAllowRendering

public boolean getAllowRendering()

Checks to see if rendering should be allowed. Defaults to true but will return false after a #stop directive.

Returns:

true if rendering is allowed, false if no rendering should occur

setAllowRendering

public void setAllowRendering(boolean v)

Set whether rendering is allowed. Defaults to true but is set to false after a #stop directive.

attachEventCartridge

public EventCartridge attachEventCartridge(EventCartridge ec)

Specified by:

attachEventCartridge in interface InternalEventContext

getEventCartridge

public EventCartridge getEventCartridge()

Specified by:

getEventCartridge in interface InternalEventContext