org.apache.velocity.context
Class AbstractContext

java.lang.Object
  extended by org.apache.velocity.context.AbstractContext
All Implemented Interfaces:
Context, InternalEventContext
Direct Known Subclasses:
VelocityContext

public abstract class AbstractContext
extends Object
implements Context

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 :

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 732250 2009-01-07 07:37:10Z byron $
Author:
Geir Magnusson Jr., Fedor Karpelevitch, Jason van Zyl

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.
 Context getChainedContext()
          returns innerContext if one is chained
 int getCurrentMacroCallDepth()
          get the current macro call depth
 String getCurrentMacroName()
          get the current macro name
 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
 List getMacroLibraries()
          Get the macro library list for the current template.
 Object[] getMacroNameStack()
          get the current macro name stack
 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 popCurrentMacroName()
          remove the current macro name from stack
 void popCurrentTemplateName()
          remove the current template name from stack
 void pushCurrentMacroName(String s)
          set the current macro name on top of 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 setCurrentResource(Resource r)
           
 void setMacroLibraries(List macroLibraries)
          Set the macro library list for the current template.
 
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 engine.

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 engine.

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 engine.

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.

pushCurrentMacroName

public void pushCurrentMacroName(String s)
set the current macro name on top of stack

Parameters:
s - current macro name

popCurrentMacroName

public void popCurrentMacroName()
remove the current macro name from stack


getCurrentMacroName

public String getCurrentMacroName()
get the current macro name

Returns:
String current macro name

getCurrentMacroCallDepth

public int getCurrentMacroCallDepth()
get the current macro call depth

Returns:
int current macro call depth

getMacroNameStack

public Object[] getMacroNameStack()
get the current macro name stack

Returns:
Object[] with the macro 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)
See Also:
InternalHousekeepingContext.setCurrentResource(org.apache.velocity.runtime.resource.Resource)

getCurrentResource

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

Returns:
The current resource.
See Also:
InternalHousekeepingContext.getCurrentResource()

setMacroLibraries

public void setMacroLibraries(List macroLibraries)
Set the macro library list for the current template.

Parameters:
macroLibraries - list of macro libraries to set
See Also:
InternalHousekeepingContext.setMacroLibraries(List)

getMacroLibraries

public List getMacroLibraries()
Get the macro library list for the current template.

Returns:
List of macro library names
See Also:
InternalHousekeepingContext.getMacroLibraries()

attachEventCartridge

public EventCartridge attachEventCartridge(EventCartridge ec)
Specified by:
attachEventCartridge in interface InternalEventContext
Returns:
The old EventCartridge.
See Also:
InternalEventContext.attachEventCartridge(org.apache.velocity.app.event.EventCartridge)

getEventCartridge

public EventCartridge getEventCartridge()
Specified by:
getEventCartridge in interface InternalEventContext
Returns:
The current EventCartridge.
See Also:
InternalEventContext.getEventCartridge()


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