Bugs item #1618750, was opened at 2006-12-19 14:46
Message generated for change (Comment added) made by petehak
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Andre Nurzenski (nurzensa)
Assigned to: Nobody/Anonymous (nobody)
Summary: ClassCastException while creating org.dom4j.DocumentFactory
Initial Comment:
I am using dom4j 1.6.1 within an OSGi-Bundle in a rich client application. When
running the application, the following call causes a DocumentException:
SAXReader saxReader = new SAXReader();
Document document = saxReader.read(InputStream);
The DocumentException contains a nested ClassCastException:
java.lang.ClassCastException: org.dom4j.DocumentFactory
at org.dom4j.DocumentFactory.getInstance(DocumentFactory.java:97)
at org.dom4j.io.SAXReader.getDocumentFactory(SAXReader.java:645)
at org.dom4j.io.SAXReader.createContentHandler(SAXReader.java:969)
at org.dom4j.io.SAXReader.read(SAXReader.java:449)
at org.dom4j.io.SAXReader.read(SAXReader.java:343)
The cause of this exception seems to be the way the DocumentFactory class is
loaded in org.dom4j.util.SimpleSingleton, line 38, using the context class
loader.
When using Class.forName() to load the class (same way as in 1.6), the problem
does not occur.
As this seems to be a very special problem within an OSGi-Environment and its
class loading mechanism, I'm not sure if this issue can be considered as a bug.
Please contact me if you need further information.
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Comment By: Pete (petehak)
Date: 2007-12-19 10:42
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Is DocumentFactory thread-safe?
I removed its internal use of SimpleSingleton and replaced it with static
class to store one DocumentFactory instance. Can I use the same
DocumentFactory instance for concurrent threads or should there be one
DocumentFactory per thread?
If that class is not thread-safe, then this fix is not applicable. We have
to find some other way, like discarding the caching compleletely and create
a new instance of DocumentFactory for each call. This naturally comes with
a performance penalty, but how big, i dunno.
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Comment By: Filip Jirsák (filipjirsak)
Date: 2007-12-18 13:17
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May be this is bug in dom4j. Though you can pass on DocumentFactory when
creating SAXParser – dom4j doesn't need creating its own instance of
DocumentFactory with buggy singleton afterwards.
You can try this:
DocumentFactory documentFactory = new DocumentFactory();
SAXReader saxReader = new SAXReader(documentFactory);
Document document = saxReader.read(InputStream);
DocumentFactory should be singleton better, but you can manage it your
correct way. For example:
public class DocumentFactorySingleton {
public static DocumentFactory instance = new DocumentFactory();
}
SAXReader saxReader = new SAXReader(DocumentFactorySingleton.instance);
Document document = saxReader.read(InputStream);
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Comment By: Pete (petehak)
Date: 2007-12-18 12:58
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We have run into this same problem with Weblogic Server 10.0, Dom4j 1.6.1
contained in several EAR files.
The occurrence of the problem seems quite random. We can test applications
for days, and then suddenly this exception is thrown. After a Weblogic
reboot, everything works fine, until the problem occurs again after some
period of time.
We must do something about this. Should we include dom4j in system
classpath, change Dom4j's class loading behavior described in this thread
(Class.forName..) or what?
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Comment By: shakebaby (shakebaby)
Date: 2007-08-20 05:56
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I met this with the same environment.I don't know why. I guess it may be a
bug .
Can any one give me a reply please ? Thank you !
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Comment By: Kevin Galligan (kpgalligan)
Date: 2007-03-19 02:46
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I'm having the same problem. Just started out of nowhere. I had
installed jdk1.6, then tried to uninstall it and put 1.5 back, and ever
since that happened there have been problems. My code was working before,
though, so this is a little frustrating.
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