Re: jdom2 runtime

Thanks Rolf.

I am able to run new SAXBuilder(new XMLReaderSAX2Factory(false,
"org.apache.xerces.parsers.SAXParser")); OK.

I do have xercesImpl and xml-apis in my classpath.  But I cannot yet get the
no arg constructor (new SAXBuilder()) to run.

Is there some advantage to using the no arg constructor?  

Thanks, Craig

 

From: Rolf Lear [mailto:[email protected]] 
Sent: Tuesday, August 21, 2012 12:39 PM
To: Craig Christophersen
Cc: [email protected]
Subject: Re: [jdom-interest] jdom2 runtime

 

In JDOM 2.x the new SAXBuilder()   (no arguments) will use regular JAXP
API's to get the right SAX Parser for your system.

The JAXP process is described here:
http://docs.oracle.com/javase/7/docs/api/javax/xml/parsers/SAXParserFactory.
html#newInstance%28%29

In most cases, if you want to use a particular parser (xerces, for example),
all you need to do is add the jar to the classpath. As a fallback mechanism,
the standard JRE has an XML Parser built in already (an older version of
xerces with some customizations - one of which is that it is not in the
regular apache package.... so you cannot call it
org.apache.xerces.parsers.SAXParser). So, you do not need to have any
third-party jar unless you want one. I would still recommend adding xerces
to your classpath though (and with it, you will want the xml-apis.jar).

So, in your 'old' code, if you used to do:

... = new SAXBuilder("org.apache.xerces.parsers.SAXParser");

then I suggest you either:
   -  add (only) xerces (with xmlapis.jar) to the classpath, and use the
plain ... = new SAXBuilder(); constructor....
   -  add xerces to the classpath, use ... = new SAXBuilder(new
XMLReaderSAX2Factory(false, "org.apache.xerces.parsers.SAXParser"));

Note though, that the deprecated/'old' constructor new
SAXBuilder("org.apache.xerces.parsers.SAXParser"); will still work (with a
deprecated warning) if you have the xerces.jar in your classpath.

I recommend that you use the (newer) JAXP API for constructing SAXBuilders.
You can still customize it with a particular library.

I note that there is a lack of functionality in JDOM for using JAXP with a
custom factory.... I will add that.... I think.... see issue #89

For what it's worth, the documentation on the org.jdom.input.sax is fairly
comprehensive:
http://www.jdom.org/docs/apidocs/org/jdom2/input/sax/package-summary.html
even though it does not have an example of what you want (although it has
other examples).

Also, the source code for the deprecated constructor is educational... :
https://github.com/hunterhacker/jdom/blob/master/core/src/java/org/jdom2/inp
ut/SAXBuilder.java#L266
and
https://github.com/hunterhacker/jdom/blob/master/core/src/java/org/jdom2/inp
ut/SAXBuilder.java#L288

I will consider the usage of a JAXP custom factory using the 'other' JAXP
constructor:
http://docs.oracle.com/javase/6/docs/api/javax/xml/parsers/SAXParserFactory.
html#newInstance%28java.lang.String,%20java.lang.ClassLoader%29

Issue #89: https://github.com/hunterhacker/jdom/issues/89

Rolf

On 21/08/2012 1:23 PM, Craig Christophersen wrote:

Hello;

While I now have jdom2 compiling OK in an application, I am running into
runtime problems with SAXBuilder.

 

With previous jdom both SAXBuilder builder = new SAXBuilder();  and
SAXBuilder builder = new SAXBuilder("org.apache.xerces.parsers.SAXParser");
worked for constructing a SAXBuilder.

 

Question:

So now to use new SAXBuilder() (which uses JAXP) do I need something
additional in my classpath??  

Or is there somewhere I can see an example of what is mentioned in the
migration guide ---   Deprecated. use
<http://www.jdom.org/docs/apidocs/org/jdom2/input/SAXBuilder.html#SAXBuilder
%28org.jdom2.input.sax.XMLReaderJDOMFactory%29>
SAXBuilder(XMLReaderJDOMFactory) with
<http://www.jdom.org/docs/apidocs/org/jdom2/input/sax/XMLReaderSAX2Factory.h
tml#XMLReaderSAX2Factory%28boolean,%20java.lang.String%29>
XMLReaderSAX2Factory.XMLReaderSAX2Factory(boolean, String)?

 

Thanks,            

 

 

Craig Christophersen

Software Developer

Synesis7

[email protected]

 






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