Mark,
In general if there was a classloader from the thread and the class I would
pick one and try to load my resource. If I got nothing I would try the other
one. Something like:
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
InputStream in = classLoader.getResourceAsStream();
if( in == null){
classLoader = this.getClass().getClassLoader();
in = classLoader.getResourceAsStream();
}
if( in == null)
//all hope is lost...
else
// do something cool.
Unfortunately this is the code in ClassFieldExtractorFactory:
// use bytes to get a class
final ByteArrayClassLoader classLoader =
new ByteArrayClassLoader(
Thread.currentThread().getContextClassLoader() );
final Class newClass = classLoader.defineClass(
className.replace( '/', '.' ), bytes );
If I was writing this I would try to take the same approach as above. If
classLoader.defineClass threw an exception I would try to create a new
ByteArrayClassLoader with the parent defined as the classloader that loaded
ClassFieldExtractorFactory. I would have to think about how to get that
classLoader though since all this is occuring in a static method.
I am not an expert on ClassLoaders so I will ask, does this make sense?
Nat
Mark Proctor-2 wrote:
>
> http://anonsvn.labs.jboss.com/labs/jbossrules/trunk/drools-compiler/src/main/java/org/drools/compiler/PackageBuilderConfiguration.java
>
> This is how we determine the classloader:
>
> public PackageBuilderConfiguration() {
> ClassLoader classLoader =
> Thread.currentThread().getContextClassLoader();
> if ( classLoader == null ) {
> classLoader = this.getClass().getClassLoader();
> }
> this.classLoader = classLoader;
> }
>
> I believe this is the normal way of doing it and to take it from the
> class, as default, may break other systems.
>
> Mark
>
>
>
> Nat wrote:
>> I finally found the problem. Drools has a ClassFieldExtractorFactory that
>> creates a classloader who's parent comes from
>> Thread.currentThread().getContextClassLoader(). This willl cause the
>> drools
>> classloader to not be able to see the plugin classes. A better way to do
>> it
>> would have been to check both the context and the current classes
>> classloader. Since that isn't going to happen I'll have to shift things
>> around a bit to make it work.
>>
>> Nat
>>
>>
>>
>> Edson Tirelli-3 wrote:
>>
>>> Nat,
>>>
>>> What kind of environment are you working on? Stand-alone JSE, app
>>> server JEE, etc?
>>> I'm asking because yesterday I had to fix the same issue for a
>>> JBRules Ant task and in the end it was an ant classloader that was
>>> messing with some stuff jbrules needs.
>>>
>>> So, basically, if you are sure you have all dependencies on
>>> classpath, it is probably a classloader issue.
>>>
>>> []s
>>> Edson
>>>
>>>
>>> Nat wrote:
>>>
>>>
>>>> At runtime I am getting a NoClassDefFound exception for the class
>>>> org.drools.base.BaseClassFieldExtractor when I try to call the method
>>>> addPackageFromDrl( src) from PackageBuilder. I know the class is in
>>>> drools-core.jar. I know that I can load and instansiate
>>>> org.drools.RuleBaseFactory which is in the same jar file so I know the
>>>> jar
>>>> is in my classpath. I'm guessing BaseClassFieldExtractor needs
>>>> something
>>>> that is missing???
>>>>
>>>> Does anyone have any ideas as to where I'm going wrong or how I can
>>>> find
>>>> what is missing?
>>>>
>>>> I know this is somewhat vague but I'm at a loss of where to look next.
>>>> Thanks in advance for your time,
>>>> Nat
>>>>
>>>>
>>>>
>>> --
>>> ---
>>> Edson Tirelli
>>> Software Engineer - JBoss Rules Core Developer
>>> Office: +55 11 3124-6000
>>> Mobile: +55 11 9218-4151
>>> JBoss, a division of Red Hat @ www.jboss.com
>>>
>>> IT executives: Red Hat still #1 for value
>>> http://www.redhat.com/promo/vendor/
>>>
>>>
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>>>
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>>>
>>>
>>>
>>>
>>
>>
>
>
>
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