org.apache.avalon.framework.context
Class DefaultContext

java.lang.Object
  |
  +--org.apache.avalon.framework.context.DefaultContext

All Implemented Interfaces:

Context

public class DefaultContext

extends Object

implements Context

Default implementation of Context. This implementation is a static hierarchial store.

Version:

CVS $Revision: 1.25 $ $Date: 2003/02/11 15:58:40 $

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.

Methods inherited from class java.lang.Object

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

Constructor Detail

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)

DefaultContext

public DefaultContext(Map contextData)

Create a Context with specified data.

Parameters:

contextData - the context data

DefaultContext

public DefaultContext(Context parent)

Create a Context with specified parent.

Parameters:

parent - the parent Context (may be null)

DefaultContext

public DefaultContext()

Create a Context with no parent.

Method Detail

get

public Object get(Object key)
           throws ContextException

Retrieve an item from the Context.

Specified by:

get in interface Context

Parameters:

key - the key of item

Returns:

the item stored in context

Throws:

ContextException - if item not present

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

Throws:

IllegalStateException - if context is read only

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

Throws:

IllegalStateException - if context is read only

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)

makeReadOnly

public void makeReadOnly()

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

checkWriteable

protected final void checkWriteable()
                             throws IllegalStateException

Utility method to check if context is writeable and if not throw exception.

Throws:

IllegalStateException - if context is read only