Hello to all.
I've been using Struts for a while now, with great success! Thanks to the
developers! However, I've found a bit of a problem using Struts 1.1 with
Dynamo 5.6.1 Apologies in advance if this is more appropriate to the user
mailing list - I wasn't sure!
Dynamo implements J2EE 1.2, which includes the Servlet 2.2 specs, which I
gather can sometimes be a bit vague on the subject of web application
context class loaders. I've been trying to get the tag libraries working
correctly. When using say a <bean:define> tag, an exception is thrown when
trying to instantiate the page by dynamo:
[ERROR] MessageResourcesFactory - -MessageResourcesFactory.createFactory
<java.lang.ClassNotFoundException:
org.apache.struts.util.PropertyMessageResourcesFactory>java.lang.ClassNotFoundException:
org.apache.struts.util.PropertyMessageResourcesFactory
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:286)
at java.lang.ClassLoader.loadClass(ClassLoader.java:255)
at
org.apache.struts.util.RequestUtils.applicationClass(RequestUtils.java:182)
at
org.apache.struts.util.MessageResourcesFactory.createFactory(MessageResourcesFactory.java:192)
at
org.apache.struts.util.MessageResources.getMessageResources(MessageResources.java:576)
at
org.apache.struts.util.RequestUtils.<clinit>(RequestUtils.java:138)
at
org.apache.struts.util.MessageResourcesFactory.createFactory(MessageResourcesFactory.java:192)
at
org.apache.struts.util.MessageResources.getMessageResources(MessageResources.java:576)
at
org.apache.struts.taglib.bean.DefineTag.<clinit>(DefineTag.java:88)
at java.lang.Class.newInstance0(Native Method)
at java.lang.Class.newInstance(Class.java:237)
at
atg.servlet.pagecompile.taglib.TagPool.checkOut(TagPool.java:111)
at
atg.servlet.pagecompile.taglib.TagManager.checkOutTag(TagManager.java:210)
(Extra lines cropped, and are all ATG classes)
Looking through the code for RequestUtils.applicationClass() the code
seems to try and get the current context loader:
// Look up the class loader to be used
ClassLoader classLoader =
Thread.currentThread().getContextClassLoader();
if (classLoader == null) {
classLoader = RequestUtils.class.getClassLoader();
}
// Attempt to load the specified class
return (classLoader.loadClass(className));
However, looking at the trace, I'm guessing that the getContextClassLoader
method returns the system-wide class loader (which has no knowledge of the
WEB-INF/lib contents). One fix which seems to work (at least here) is just
to comment that code and replace with
return Class.forName(className);
The main question is whether this fix is appropriate - and whether there
are any other workarounds or fixes available - presumably I would have to
put this in all the other classes where the code using the
getContextClassLoader was? I'm guessing that there was a good reason not
to use Class.forName anyway (if so, I'd be interested to know why?)
thanks in advance,
Steve.
