org.objectledge.context
Class Context

java.lang.Object
  org.objectledge.context.Context

public class Context
extends Object

Context gives the application an ability to reference arbitrary objects using String names.

The bindings are local to the calling thread. This is a convenient way of passing data associated with a stream of processing without putting them into method attributes. This is especialy convenient with data that are not needed at a specific stage of processing, but may be needed by the nested stages - for example security credentials.

Note!It is important to clear the context before the thread departs from within application boundaries - otherwise the references may prevent the objects (and as a result large graphs of objects including classes and classloaders) from being garbage collected, while being otherwise being eligible to collection.

Version:

$Id: Context.java,v 1.8 2005/11/18 11:39:33 rafal Exp $

Author:

rafal@caltha.pl

Field Summary

private static ThreadLocal

threadAttributes storage of the context attributes, specific to a thread.

Constructor Summary

Context()

Method Summary

void	clearAttributes() Removes all context attributes.
<T> T	getAttribute(Class<T> key) Return the value of a context attribute.
Object	getAttribute(String name) Return the value of a context attribute.
private Map	getAttributes()
Object	removeAttribute(Class key) Removes a context attribute.
Object	removeAttribute(String name) Removes a context attribute.
Object	setAttribute(Class key, Object value) Sets a new value of a context attribute.
Object	setAttribute(String name, Object value) Sets a new value of a context attribute.

Methods inherited from class java.lang.Object

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

Field Detail

threadAttributes

private static ThreadLocal threadAttributes

storage of the context attributes, specific to a thread.

Constructor Detail

Context

public Context()

Method Detail

getAttribute

public Object getAttribute(String name)

Return the value of a context attribute.

Parameters:

name - the attribute name.

Returns:

the value of the attribute.

getAttribute

public <T> T getAttribute(Class<T> key)

Return the value of a context attribute.

Class object and the class name String are considered to be equivalent keys.

Type Parameters:

T - the type reflected by key Class object, to avoid casting on the caller's side.

Parameters:

key - a Class key of the attribute.

Returns:

the value of the attribute.

setAttribute

public Object setAttribute(String name,
                           Object value)

Sets a new value of a context attribute.

Parameters:

name - the name of the attribute.

value - the new value of the attribute.

Returns:

the old value of the attribute.

setAttribute

public Object setAttribute(Class key,
                           Object value)

Sets a new value of a context attribute.

Class object and the class name String are considered to be equivalent keys.

Parameters:

key - Class key of the attribute.

value - the new value of the attribute.

Returns:

the old value of the attribute.

removeAttribute

public Object removeAttribute(String name)

Removes a context attribute.

Parameters:

name - the name of the attribute.

Returns:

the old value of the attribute.

removeAttribute

public Object removeAttribute(Class key)

Removes a context attribute.

Class object and the class name String are considered to be equivalent keys.

Parameters:

key - Class key of the attribute.

Returns:

the old value of the attribute.

clearAttributes

public void clearAttributes()

Removes all context attributes.

getAttributes

private Map getAttributes()