org.apache.commons.betwixt.digester
Class XMLIntrospectorHelper

java.lang.Object
  |
  +--org.apache.commons.betwixt.digester.XMLIntrospectorHelper

public class XMLIntrospectorHelper

extends java.lang.Object

XMLIntrospectorHelper a helper class for common code shared between the digestor and introspector.

Version:

$Id: XMLIntrospectorHelper.java,v 1.16 2003/01/08 22:07:21 rdonkin Exp $

Author:

James Strachan, Martin van den Bemt

Field Summary

protected static org.apache.commons.logging.Log

log Log used for logging (Doh!)

Constructor Summary

XMLIntrospectorHelper()
Base constructor

Method Summary

static void	configureProperty(AttributeDescriptor attributeDescriptor, java.beans.PropertyDescriptor propertyDescriptor) Configure an AttributeDescriptor from a PropertyDescriptor
static void	configureProperty(ElementDescriptor elementDescriptor, java.beans.PropertyDescriptor propertyDescriptor) Configure an ElementDescriptor from a PropertyDescriptor
static NodeDescriptor	createDescriptor(java.beans.PropertyDescriptor propertyDescriptor, boolean useAttributesForPrimitives, XMLIntrospector introspector) Process a property.
static void	defaultAddMethods(XMLIntrospector introspector, ElementDescriptor rootDescriptor, java.lang.Class beanClass) Add any addPropety(PropertyType) methods as Updaters which are often used for 1-N relationships in beans.
protected static ElementDescriptor	findGetCollectionDescriptor(XMLIntrospector introspector, ElementDescriptor rootDescriptor, java.lang.String propertyName) Attempts to find the element descriptor for the getter property that typically matches a collection or array.
static org.apache.commons.logging.Log	getLog() Gets the current logging implementation.
static boolean	isLoopType(java.lang.Class type) Is this a loop type class?
static boolean	isPrimitiveType(java.lang.Class type) Is this a primitive type?
protected static void	makeElementDescriptorMap(ElementDescriptor rootDescriptor, java.util.Map map) Creates a map where the keys are the property names and the values are the ElementDescriptors
static void	setLog(org.apache.commons.logging.Log aLog) Sets the current logging implementation.
protected static void	swapDescriptor(ElementDescriptor rootDescriptor, ElementDescriptor oldValue, ElementDescriptor newValue) Traverse the tree of element descriptors and find the oldValue and swap it with the newValue.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static org.apache.commons.logging.Log log

Log used for logging (Doh!)

Constructor Detail

XMLIntrospectorHelper

public XMLIntrospectorHelper()

Base constructor

Method Detail

getLog

public static org.apache.commons.logging.Log getLog()

Gets the current logging implementation.

Returns:

current log

setLog

public static void setLog(org.apache.commons.logging.Log aLog)

Sets the current logging implementation.

Parameters:

aLog - use this Log

createDescriptor

public static NodeDescriptor createDescriptor(java.beans.PropertyDescriptor propertyDescriptor,
                                              boolean useAttributesForPrimitives,
                                              XMLIntrospector introspector)
                                       throws java.beans.IntrospectionException

Process a property. Go through and work out whether it's a loop property, a primitive or a standard. The class property is ignored.

Parameters:

propertyDescriptor - create a NodeDescriptor for this property

useAttributesForPrimitives - write primitives as attributes (rather than elements)

introspector - use this XMLIntrospector

Returns:

a correctly configured NodeDescriptor for the property

Throws:

java.beans.IntrospectionException - when bean introspection fails

configureProperty

public static void configureProperty(ElementDescriptor elementDescriptor,
                                     java.beans.PropertyDescriptor propertyDescriptor)

Configure an ElementDescriptor from a PropertyDescriptor

Parameters:

elementDescriptor - configure this ElementDescriptor

propertyDescriptor - configure from this PropertyDescriptor

configureProperty

public static void configureProperty(AttributeDescriptor attributeDescriptor,
                                     java.beans.PropertyDescriptor propertyDescriptor)

Configure an AttributeDescriptor from a PropertyDescriptor

Parameters:

attributeDescriptor - configure this AttributeDescriptor

propertyDescriptor - configure from this PropertyDescriptor

defaultAddMethods

public static void defaultAddMethods(XMLIntrospector introspector,
                                     ElementDescriptor rootDescriptor,
                                     java.lang.Class beanClass)

Add any addPropety(PropertyType) methods as Updaters which are often used for 1-N relationships in beans.
The tricky part here is finding which ElementDescriptor corresponds to the method. e.g. a property 'items' might have an Element descriptor which the method addItem() should match to.
So the algorithm we'll use by default is to take the decapitalized name of the property being added and find the first ElementDescriptor that matches the property starting with the string. This should work for most use cases. e.g. addChild() would match the children property.

Parameters:

introspector - use this XMLIntrospector for introspection

rootDescriptor - add defaults to this descriptor

beanClass - the Class to which descriptor corresponds

isLoopType

public static boolean isLoopType(java.lang.Class type)

Is this a loop type class?

Parameters:

type - is this Class a loop type?

Returns:

true if the type is a loop type

isPrimitiveType

public static boolean isPrimitiveType(java.lang.Class type)

Is this a primitive type?

Parameters:

type - is this Class a primitive type?

Returns:

true for primitive types

findGetCollectionDescriptor

protected static ElementDescriptor findGetCollectionDescriptor(XMLIntrospector introspector,
                                                               ElementDescriptor rootDescriptor,
                                                               java.lang.String propertyName)

Attempts to find the element descriptor for the getter property that typically matches a collection or array. The property name is used to match. e.g. if an addChild() method is detected the descriptor for the 'children' getter property should be returned.

Parameters:

introspector - use this XMLIntrospector

rootDescriptor - the ElementDescriptor whose child element will be searched for a match

propertyName - the name of the 'adder' method to match

Returns:

ElementDescriptor for the matching getter

makeElementDescriptorMap

protected static void makeElementDescriptorMap(ElementDescriptor rootDescriptor,
                                               java.util.Map map)

Creates a map where the keys are the property names and the values are the ElementDescriptors

Parameters:

rootDescriptor - the values of the maps are the children of this ElementDescriptor index by their property names

map - the map to which the elements will be added

swapDescriptor

protected static void swapDescriptor(ElementDescriptor rootDescriptor,
                                     ElementDescriptor oldValue,
                                     ElementDescriptor newValue)

Traverse the tree of element descriptors and find the oldValue and swap it with the newValue. This would be much easier to do if ElementDescriptor supported a parent relationship.

Parameters:

rootDescriptor - traverse child graph for this ElementDescriptor

oldValue - replace this ElementDescriptor

newValue - replace with this ElementDescriptor