org.apache.avalon.framework.context

Class DefaultContext

Implemented Interfaces:
Context

public class DefaultContext
extends java.lang.Object
implements Context

Default implementation of Context. This implementation is a static hierarchial store.
Version:
CVS $Revision: 1.27 $ $Date: 2004/02/11 14:34:26 $
Author:
Avalon Development Team

Constructor Summary

DefaultContext()
Create a Context with no parent.
DefaultContext(Context parent)
Create a Context with specified parent.
DefaultContext(Map contextData)
Create a Context with specified data.
DefaultContext(Map contextData, Context parent)
Create a Context with specified data and parent.

Method Summary

protected void
checkWriteable()
Utility method to check if context is writeable and if not throw exception.
Object
get(Object key)
Retrieve an item from the Context.
protected Map
getContextData()
Utility method to retrieve context data.
protected Context
getParent()
Get parent context if any.
void
hide(Object key)
Hides the item in the context.
void
makeReadOnly()
Make the context read-only.
void
put(Object key, Object value)
Helper method fo adding items to Context.

Constructor Details

DefaultContext

public DefaultContext()
Create a Context with no parent.

DefaultContext

public DefaultContext(Context parent)
Create a Context with specified parent.
Parameters:
parent - the parent Context (may be null)

DefaultContext

public DefaultContext(Map contextData)
Create a Context with specified data.
Parameters:
contextData - the context data

DefaultContext

public DefaultContext(Map contextData,
                      Context parent)
Create a Context with specified data and parent.
Parameters:
contextData - the context data
parent - the parent Context (may be null)

Method Details

checkWriteable

protected final void checkWriteable()
            throws IllegalStateException
Utility method to check if context is writeable and if not throw exception.

get

public Object get(Object key)
            throws ContextException
Retrieve an item from the Context.
Parameters:
key - the key of item
Returns:
the item stored in context

getContextData

protected final Map getContextData()
Utility method to retrieve context data.
Returns:
the context data

getParent

protected final Context getParent()
Get parent context if any.
Returns:
the parent Context (may be null)

hide

public void hide(Object key)
            throws IllegalStateException
Hides the item in the context. After remove(key) has been called, a get(key) will always fail, even if the parent context has such a mapping.
Parameters:
key - the items key

makeReadOnly

public void makeReadOnly()
Make the context read-only. Any attempt to write to the context via put() will result in an IllegalStateException.

put

public void put(Object key,
                Object value)
            throws IllegalStateException
Helper method fo adding items to Context.
Parameters:
key - the items key
value - the item