Re: [dom4j-dev] generating a QName

[James Strachan]

Hi Mike   BTW I often find this HTML mail goes wonky ;-) ----- Original Message ----- From: Mike Skells (ebizz-consulting) To: [EMAIL PROTECTED] Sent: Saturday, April 20, 2002 11:03 PM Subject: [dom4j-dev] generating a QName Hi, I was tidying some code and came across a problem. I need to retrieve a attribute based on namespace and name, but via the Element.attribute(Qname) method. I note that there is a convenience method to generate a QName based on the prefix and the attribute name, but no such method for Namespace and name Taking a similar line to that in Element.getQName(String) I could use Element.getDocumentFactory().createQName( name, myNamespace ); but getDocument is protected, and part of AbstractElement, not Element.   I have 3 questions 1.       What is the preferred way to generate a QName given a namespace and name? There should be something better than appending the prefix and name!   There's either of the following...   QName qname = QName.get( "myURI", "foo:bar" );   Or   DocumentFactory factory = new DocumentFactory(); QName qname = factory.createQName( "myURI", "foo:bar" );   The former uses a singleton cache, the latter uses a cache per factory instance.   2.       Is here any reason why getDocumentFactory is not part of the Node interface?   I've been really really close to adding it. I think it might lots of make sense. Its part of the implementation interface; there's a protected getDocumentFactory() method. 3.       Looking at Qname there appears to be little documentation – I presume that this class is only intended to be constructed by a DocumentFactory, or by Nodes Its intended to represent a tuple of namespace URI, namespace prefix and local name. Creating your own via the static helpers on QName or via a DocumentFactory is fine too.   QName implements equals() based on normal namespace rules, that the local name and namespace URIs must match, the prefix is ignored.     It can often be useful to declare QNames as static constant enumerations in your code. e.g. here's a snippet of code from org.dom4j.datatype.SchemaParser...   private static final Namespace XSD_NAMESPACE     = Namespace.get( "xsd", "http://www.w3.org/2001/XMLSchema" );   private static final QName XSD_ELEMENT = QName.get( "element", XSD_NAMESPACE ); private static final QName XSD_ATTRIBUTE = QName.get( "attribute", XSD_NAMESPACE ); private static final QName XSD_SIMPLETYPE = QName.get( "simpleType", XSD_NAMESPACE ); James