| PropertyDescriptor subclass that describes an indexed set of read/write
methods to get a property. Unlike IndexedPropertyDescriptor this allows
the "key" to be an arbitrary object rather than just an int. Consequently
it does not have a "readMethod" or "writeMethod" because it only expects
a pattern like:
public void setProperty(KeyType, ValueType);
public ValueType getProperty(KeyType);
and does not require the methods that access it as an array. OGNL can
get away with this without losing functionality because if the object
does expose the properties they are most probably in a Map and that case
is handled by the normal OGNL property accessors.
For example, if an object were to have methods that accessed and "attributes"
property it would be natural to index them by String rather than by integer
and expose the attributes as a map with a different property name:
public void setAttribute(String name, Object value);
public Object getAttribute(String name);
public Map getAttributes();
Note that the index get/set is called get/set Attribute
whereas the collection getter is called Attributes. This
case is handled unambiguously by the OGNL property accessors because the
set/getAttribute methods are detected by this object and the
"attributes" case is handled by the MapPropertyAccessor.
Therefore OGNL expressions calling this code would be handled in the
following way:
| OGNL Expression |
Handling |
|---|
attribute["name"] |
Handled by an index getter, like getAttribute(String). |
attribute["name"] = value |
Handled by an index setter, like setAttribute(String, Object). |
attributes["name"] |
Handled by MapPropertyAccessor via a Map.get(). This
will not go through the index get accessor.
|
attributes["name"] = value |
Handled by MapPropertyAccessor via a Map.put(). This
will not go through the index set accessor.
|
author:
Luke Blanshard (blanshlu@netscape.net)
author:
Drew Davidson (drew@ognl.org) | 