[jdom-interest] Problem with DOCTYPE and SAXBuilder

[Jason Hunter]

Here's what's going on.  The following in the DTD...

<!ATTLIST taglib id ID #IMPLIED
          xmlns CDATA #FIXED
               
"http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"
>

sets the default namespace to http://java.sun.com/.....  This requires
that when you access an element by name in JDOM you pass in the proper
Namespace for the element like this:

Namespace ns = Namespace.getNamespace("", "http://.....");
List tags = taglib.getChildren("tag", ns);

You were asking for children outside a namespace, of which there were
none.  When you removed the xmlns in the DTD, then things worked as
expected.  The reason DOMBuilder "worked" for you without you needing to
pass in a namespace is because DOMBuilder namespaces in beta5 were
broken and those elements weren't being put in the proper namespace. 
DOMBuilder is fixed in the latest snapshot, so you'll need to do the
right thing now always, as shown above.

-jh-

Ewan Harrow wrote:
> 
> I am new to JDOM but I am having a spot of difficulty getting any
> children of the root element using a document created with SAXBuilder
> and a particular DTD.  The xml below is from a JSP Taglib TLD.
> 
> <?xml version="1.0" encoding="ISO-8859-1" ?>
> 
> <!DOCTYPE JSPTAGLIB.1_1
>         PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
>         "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd">
> 
> <taglib>
>     <tlibversion>1.0</tlibversion>
>     <jspversion>1.1</jspversion>
>     <shortname>sample</shortname>
>     <info>
> 
> Sample tag library template.
> Contains one sample tag with an attribute and a variable.
> 
> 
>     </info>
> 
>     <tag>
>         <name>sample</name>
>         <tagclass>pkg.SampleTag</tagclass>
>         <bodycontent>JSP</bodycontent>
>         <info>
> A sample tag.
> 
> 
>         </info>
> 
>         <attribute>
>             <name>sampleAttribute</name>
>             <type>String</type>
>             <rtexprvalue>true</rtexprvalue>
>             <required>false</required>
>         </attribute>
> 
>     </tag>
> 
> </taglib>
> 
> My code is as follows:
> 
>     ...
>     SAXBuilder builder = new SAXBuilder();
>     //DOMBuilder builder = new DOMBuilder();
> 
>     try {
>       // Build the JDOM Document
>       Document doc = builder.build(new File("taglib.tld"));
>       //Document doc = builder.build(file);
> 
>       Element taglib = doc.getRootElement();
>       System.out.println(taglib.getName());
> 
>       List tags = taglib.getChildren("tag");
>       System.out.println("This TLD has "+ tags.size() +" tags:");
>       Iterator i = tags.iterator();
>       while (i.hasNext()) {
>         Element tag = (Element) i.next();
>         System.out.print("\t" + tag.getChild("name").getTextTrim() +
>                           " for " +
> tag.getChild("info").getTextTrim());
>         List attributesList = tag.getChildren("attribute");
>         System.out.println(" (it has " + attributes.size() + "
> attributes)");
>       }
>     } catch (JDOMException ex) {
>       System.out.println(ex);
>     }
> 
> The expected output should be:
> 
> taglib
> This TLD has 1 tags:
>         sample for A sample tag. (it has 0 attributes)
> 
> Instead I get:
> 
> taglib
> This TLD has 0 tags:
> 
> I switched the builder to be of type DOMBuilder and it works as
> expected.
> 
> Is this a bug or expected behaviour?  I am using JDOM-B5, jdk1.3,
> win2000.  If it helps I had the same problem using Xalan XPath support
> - and narrowed the problem down to the DTD and a namespace issue.  The
> DTD for tld files has a taglib element defined as
> 
> <!ELEMENT taglib (tlibversion, jspversion?, shortname, uri?, info?,
> tag+) >
> <!ATTLIST taglib id ID #IMPLIED
>           xmlns CDATA #FIXED
>                 "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"
> >
> 
> removing the
>    xmlns CDATA #FIXED
> "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"
> 
> and running again with XPath/Xalan and SAXBuilder did the trick.
> 
> While I am at it when setting the DOCTYPE to SYSTEM the URI of the DTD
> (same directory as tld) needed a path from the working directory with
> DOMBuilder but not SAXBuilder - got a JDOMException file not found.
> 
> Ewan
> 
> =====
> Ewan Harrow                ewan at harrow.org
>  mb: 07092 108950           http://www.harrow.org
>  http://www.ewanharrow.com  http://travel.ewanharrow.com
> 
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