Issue1537

I'm using jython2.5.1 in MATLAB's JVM. Upon trying to parse an XML file with ElementTree, XMLParser.__init__ tries to get XMLReaderFactory to find "org.python.apache.xerces.parsers.SAXParser". Probably due to limitations in MATLAB's stupid classloader, this does not work (throws a SAXException/ClassNotFoundException)

The only relevant comment on why this weird name is used is expat.py line 51: "Name mangled by jarjar?". 

Manually setting expat._xerces_parser to "org.apache.xerces.parsers.SAXParser" resolves the issue.

Perhaps a try block around the XMLReaderFactory call?

Hmm, that's odd.

If the classorg.python.apache.xerces.parsers.SAXParser is not found, then it should throw an ImportError.

Please can you try these statements on a jython command line and report the results?

>>> import org.python.apache.xerces.parsers.SAXParser
>>> import org.apache.xerces.parsers.SAXParser

Thanks.

Due to the way MATLAB manhandles its filehandles I can't use a real Jython prompt, but I can push to an InteractiveConsole just fine. Here are the results, plus the results with my workaround:

>> ic = org.python.util.InteractiveConsole();
>> ic.push('import org.python.apache.xerces.parsers.SAXParser');
>> ic.push('import org.apache.xerces.parsers.SAXParser');
>> ic.push('import xml.etree.ElementTree as etree');
>> ic.push('x = etree.parse("test.xml")');
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/amd/ss01/export/homes16/kwatford/TUF/jlib/jython-2.5.1.jar/Lib/xml/etree/ElementTree.py", line 862, in parse
  File "/amd/ss01/export/homes16/kwatford/TUF/jlib/jython-2.5.1.jar/Lib/xml/etree/ElementTree.py", line 581, in parse
  File "/amd/ss01/export/homes16/kwatford/TUF/jlib/jython-2.5.1.jar/Lib/xml/etree/ElementTree.py", line 1120, in __init__
  File "/amd/ss01/export/homes16/kwatford/TUF/jlib/jython-2.5.1.jar/Lib/xml/parsers/expat.py", line 63, in ParserCreate
  File "/amd/ss01/export/homes16/kwatford/TUF/jlib/jython-2.5.1.jar/Lib/xml/parsers/expat.py", line 91, in __init__
	at org.xml.sax.helpers.XMLReaderFactory.loadClass(Unknown Source)
	at org.xml.sax.helpers.XMLReaderFactory.createXMLReader(Unknown Source)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)

org.xml.sax.SAXException: java.lang.ClassNotFoundException: org.python.apache.xerces.parsers.SAXParser
>> ic.push('import xml.parsers.expat');
>> ic.push('xml.parsers.expat._xerces_parser = "org.apache.xerces.parsers.SAXParser"');
>> ic.push('x = etree.parse("test.xml")');
>> ic.push('print x');
<xml.etree.ElementTree.ElementTree instance at 0x2>

Please can you do just this bit?

>> ic.push('import org.python.apache.xerces.parsers.SAXParser');

I want to see what it generates. It should generate an ImportError.

As you can see, that's the first thing I did, and no exception was thrown. I just tried it again in a fresh session, and still no exception. They both import just fine.

I'm not sure what to do about this problem.

If 

>>> import org.python.apache.xerces.parsers.SAXParser

succeeds, then the class should be loadable.

But an attempt to instantiate the class later fails with a java.lang.ClassNotFoundException: org.python.apache.xerces.parsers.SAXParser

I can only recommend that you make use of the fix you have already identified, i.e. explicitly set the value of _xerces_parser.

I don't see what benefit a try block around the XMLReaderFactory would bring?

I'm not sure what to do about this problem.

If 

>>> import org.python.apache.xerces.parsers.SAXParser

succeeds, then the class should be loadable.

But an attempt to instantiate the class later fails with a java.lang.ClassNotFoundException: org.python.apache.xerces.parsers.SAXParser

I can only recommend that you make use of the fix you have already identified, i.e. explicitly set the value of _xerces_parser.

I don't see what benefit a try block around the XMLReaderFactory would bring?