/**
* The contents of this file are subject to the license and copyright
* detailed in the LICENSE and NOTICE files at the root of the source
* tree and available online at
*
* http://www.dspace.org/license/
*/
package org.dspace.app.xmlui.wing.element;
import org.dspace.app.xmlui.wing.AttributeMap;
import org.dspace.app.xmlui.wing.WingContext;
import org.dspace.app.xmlui.wing.WingException;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.ext.LexicalHandler;
import org.xml.sax.helpers.NamespaceSupport;
/**
* This is a class representing an individual metadata field in pseudo-dublin core
* format. The metadata elements carries generic metadata information in the
* form of an attribute-value pair.
*
* @author Scott Phillips
*/
public class Metadata extends TextContainer implements MetadataElement
{
/** The name of the metadata element */
public static final String E_METADATA = "metadata";
/** The name of the element attribute */
public static final String A_ELEMENT = "element";
/** The name of the qualifier attribute */
public static final String A_QUALIFIER = "qualifier";
/** The name of the language attribute */
public static final String A_LANGUAGE = "lang";
/** The metadata's element */
private String element;
/** The metadata's qualifier */
private String qualifier;
/** The metadata's language */
private String language;
/**
* Determine the additive model for the metadata, should
* the metadata always be added to the document or only if
* it does not already exist?
*/
private boolean allowMultiple;
/**
* Construct a new metadata.
*
* @param element
* (Required) The element of this metadata
* @param qualifier
* (May be null) The qualifier of this metadata
* @param language
* (May be null) The language of this metadata
* @param allowMultiple
* (Required) Are multiple metadata elements with the same element,
* qualifier, and language allowed?
*/
protected Metadata(WingContext context, String element, String qualifier,
String language, boolean allowMultiple) throws WingException
{
super(context);
this.element = element;
this.qualifier = qualifier;
this.language = language;
this.allowMultiple = allowMultiple;
}
/**
* If an metadata with the same element, qualifier, and language exist
* within the document should this metadata element be added into the
* document or should only one metadata be allowed.
*/
protected boolean allowMultiple()
{
return this.allowMultiple;
}
/**
* Determine if the given element, qualifier, and lang are equal to this
* metadata.
*
* @param element
* (Required) The element of this metadata
* @param qualifier
* (May be null) The qualifier of this metadata
* @param language
* (May be null) The language of this metadata
* @return True if the given parameters are equal to this metadata.
*/
protected boolean equals(String element, String qualifier, String language)
{
// Element should never be null.
if (this.element == null || element == null)
{
return false;
}
if (!stringEqualsWithNulls(this.element, element))
{
return false;
}
if (!stringEqualsWithNulls(this.qualifier, qualifier))
{
return false;
}
if (!stringEqualsWithNulls(this.language, language))
{
return false;
}
// Element, qualifier, and language are equal.
return true;
}
/**
* This is just a silly private method to make the method above easier to
* read. Compare the two parameters to see if they are equal while taking
* into account nulls. So if both values are null that is considered an
* equals.
*
* The method is meant to replace the syntax current.equals(test) so that it
* works when current is null.
*
* @param current
* (May be null) The current value.
* @param test
* (May be null) The value to be compared to current
* @return If the strings are equal.
*/
private boolean stringEqualsWithNulls(String current, String test)
{
if (current == null)
{
return (test == null);
}
else
{
return current.equals(test);
}
}
/**
* Translate into SAX events.
*
* @param contentHandler
* (Required) The registered contentHandler where SAX events
* should be routed too.
* @param lexicalHandler
* (Required) The registered lexicalHandler where lexical
* events (such as CDATA, DTD, etc) should be routed too.
* @param namespaces
* (Required) SAX Helper class to keep track of namespaces able
* to determine the correct prefix for a given namespace URI.
*/
public void toSAX(ContentHandler contentHandler, LexicalHandler lexicalHandler,
NamespaceSupport namespaces) throws SAXException
{
AttributeMap attributes = new AttributeMap();
attributes.put(A_ELEMENT, element);
if (this.qualifier != null)
{
attributes.put(A_QUALIFIER, qualifier);
}
if (this.language != null)
{
attributes.put(A_LANGUAGE, language);
}
startElement(contentHandler, namespaces, E_METADATA, attributes);
super.toSAX(contentHandler, lexicalHandler, namespaces);
endElement(contentHandler, namespaces, E_METADATA);
}
}