ObjectIndexedPropertyDescriptor (Apache Commons OGNL - Object Graph Navigation Library 4.0-SNAPSHOT API)

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org.apache.commons.ognl
Class ObjectIndexedPropertyDescriptor

java.lang.Object
  java.beans.FeatureDescriptor
      java.beans.PropertyDescriptor
          org.apache.commons.ognl.ObjectIndexedPropertyDescriptor

public class ObjectIndexedPropertyDescriptor
extends PropertyDescriptor
extends PropertyDescriptor

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/get Attribute 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), Drew Davidson (drew@ognl.org)

Constructor Summary
`ObjectIndexedPropertyDescriptor(String propertyName, Class<?> propertyType, Method indexedReadMethod, Method indexedWriteMethod)`

Method Summary
`boolean`	`equals(Object o)`
`Method`	`getIndexedReadMethod()`
`Method`	`getIndexedWriteMethod()`
`Class<?>`	`getPropertyType()`
`int`	`hashCode()`

Methods inherited from class java.beans.PropertyDescriptor
`createPropertyEditor, getPropertyEditorClass, getReadMethod, getWriteMethod, isBound, isConstrained, setBound, setConstrained, setPropertyEditorClass, setReadMethod, setWriteMethod`

Methods inherited from class java.beans.FeatureDescriptor
`attributeNames, getDisplayName, getName, getShortDescription, getValue, isExpert, isHidden, isPreferred, setDisplayName, setExpert, setHidden, setName, setPreferred, setShortDescription, setValue`

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail