net.sourceforge.stripes.util
Class OgnlCustomNullHandler

java.lang.Object
  ognl.ObjectNullHandler
      net.sourceforge.stripes.util.OgnlCustomNullHandler

All Implemented Interfaces:

NullHandler

public class OgnlCustomNullHandler
extends ObjectNullHandler

NullHandler implementation used to replace the default one that ships with Ognl. During setValue operations it will ensure that the object graph is fully formed so that the target property can be set. During get operations it will create intermediary objects as necessary, but not add them to the object graph. This allows callers to discover information about the object graph during get operations without mutating the object graph.

Author:

Tim Fennell

Field Summary

protected static String	INSTANTIATE_LEAF_NODES
protected static Map<Class,Class>	interfaceImplementations

Constructor Summary

OgnlCustomNullHandler()

Method Summary

Object

nullPropertyValue(Map context, Object target, Object property) Figures out what to do when Ognl encounters a null value in one of the expressions that it is evaluating.

Methods inherited from class ognl.ObjectNullHandler

nullMethodResult

Methods inherited from class java.lang.Object

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

Field Detail

INSTANTIATE_LEAF_NODES

protected static final String INSTANTIATE_LEAF_NODES

See Also:

Constant Field Values

interfaceImplementations

protected static final Map<Class,Class> interfaceImplementations

Constructor Detail

OgnlCustomNullHandler

public OgnlCustomNullHandler()

Method Detail

nullPropertyValue

public Object nullPropertyValue(Map context,
                                Object target,
                                Object property)

Figures out what to do when Ognl encounters a null value in one of the expressions that it is evaluating. The rules followed are as follows:

• If the expression is being evaluated to set an value, the null intermediate object is instantiated and set on its parent object.
• If the expression is a get expression and the null value is an intermediary value then the intermediary is temporarily instantiated but the object is never set on it's parent object
• If the expression is a get expression and the null value is the result of the final node in the expression, null is returned.

Specified by:

nullPropertyValue in interface NullHandler

Overrides:

nullPropertyValue in class ObjectNullHandler

Parameters:

context - the OgnlContext, actually of type OgnlContext

target - the object on which the null property was found

property - really a String, the name of the property being retrieved

Returns:

the swapped in value if one was created otherwise null