[jdom-interest] StAXBuilder, v3

[Tatu Saloranta]

Based on Bradley's suggestions, I modifed stax-based
builder a bit. It now uses UncheckecJDOMFactory (and
as diffs show, trivial change can and should be done
to sax builder as well).

I also changed Namespace to use efficient key object,
instead of rather slow StringBuffer-built Strings.
Result is about 10-15% improvement for document
building
when using StAX parsers (and most likely ditto for
sax-based ones), for namespace-heavy documents (tested
with OpenOffice xml, should be similar for Soap).
Due to this improvement, it didn't seem worth it
trying
to add additional caching like I did with previous
version (I tested it, and speed improvement wasn't
very impressive; if applied to Namespace object, would
mandata synchronized access as well).

I also attached 'cvs diff' output: in addition to one
new file, and changes to Namespace.java, there are
2 smaller changes: one-line change to SAXBuilder,
and couple of lines to build.xml to include StAX API
jar for compilation (note: that's only needed when
running, if StAX builder is actually used).

Let me know if there are other concerns about the
builder, or suggestions, or questions regarding
change(s) to Namespace class.

-+ Tatu +-

ps. I added standard license disclaimer in
StAXBuilder; not sure if that's the way to do it or
not.



		
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? lib/stax1.0.jar
? src/java/org/jdom/input/StAXBuilder.java
Index: build.xml
===================================================================
RCS file: /home/cvspublic/jdom/build.xml,v
retrieving revision 1.52
diff -r1.52 build.xml
70a71
>     <property name="stax.jar"           value="${lib.dir}/stax1.0.jar"/>
75a77
>       <pathelement location="${stax.jar}"/>
92a95
>       <pathelement location="${stax.jar}"/>
Index: src/java/org/jdom/Namespace.java
===================================================================
RCS file: /home/cvspublic/jdom/src/java/org/jdom/Namespace.java,v
retrieving revision 1.41
diff -r1.41 Namespace.java
104c104
<     private String prefix;
---
>     private final String prefix;
107c107
<     private String uri;
---
>     private final String uri;
117,119c117,120
<         namespaces.put("&", NO_NAMESPACE);
<         namespaces.put("xml&http://www.w3.org/XML/1998/namespace",
<                        XML_NAMESPACE);
---
>         //namespaces.put("&", NO_NAMESPACE);
>         namespaces.put(NO_NAMESPACE.createKey(), NO_NAMESPACE);
>         //namespaces.put("xml&http://www.w3.org/XML/1998/namespace", XML_NAMESPACE);
>         namespaces.put(XML_NAMESPACE.createKey(), XML_NAMESPACE);
146,147c147,148
<         String lookup = new StringBuffer(64)
<             .append(prefix).append('&').append(uri).toString();
---
> 
>         NSKey lookup = new NSKey(prefix, uri);
148a150
> 
273a276,323
>     }
> 
>     protected NSKey createKey() {
>         return new NSKey(prefix, uri);
>     }
> 
>     private static class NSKey
>     {
>         final String prefix;
>         final String uri;
> 
>         int hash = 0;
> 
>         public NSKey(String p, String u) {
>             prefix = p;
>             uri = u;
>         }
> 
>         public boolean equals(Object o) {
>             if (!(o instanceof NSKey)) {
>                 return false;
>             }
>             NSKey other = (NSKey) o;
>             String otherPrefix = other.prefix;
>             String otherURI = other.uri;
> 
>             return ((otherPrefix == prefix) || (otherPrefix.equals(prefix)))
>                 && ((otherURI == uri) || (otherURI.equals(uri)));
>         }
> 
>         /**
>          * Hash code should be cached, since key is only used as the
>          * hash map key. Further, it should be based on both prefix
>          * and URI -- it's quite possible to map same URI to different
>          * prefixes (at least default [empty] prefix and explicit one).
>          * Especially since prefix is probably much shorter, and costly
>          * part is URI String's hash code.
>          */
>         public int hashCode() {
>             if (hash == 0) {
>                 hash = prefix.hashCode() ^ uri.hashCode();
>             }
>             return hash;
>         }
>         
>         public String toString() { // only for debugging purposes...
>             return prefix + ":{" + uri +"}";
>         }
Index: src/java/org/jdom/input/SAXBuilder.java
===================================================================
RCS file: /home/cvspublic/jdom/src/java/org/jdom/input/SAXBuilder.java,v
retrieving revision 1.89
diff -r1.89 SAXBuilder.java
123c123
<     private JDOMFactory factory = new DefaultJDOMFactory();
---
>     private JDOMFactory factory = new UncheckedJDOMFactory();