[ http://issues.apache.org/jira/browse/DISCOVERY-1?page=all ]
Henri Yandell updated DISCOVERY-1:
----------------------------------
Bugzilla Id: (was: 36913)
Fix Version/s: 0.4
Asking on IRC, Dims thinks this one is probably fixed in the current trunk.
> [discovery] ClassLoader Problem with AXIS in Servlet Container WebSphere
> ------------------------------------------------------------------------
>
> Key: DISCOVERY-1
> URL: http://issues.apache.org/jira/browse/DISCOVERY-1
> Project: Commons Discovery
> Issue Type: Bug
> Environment: Operating System: Windows XP
> Platform: PC
> Reporter: Torge Harbig
> Fix For: 0.4
>
>
> please excuse bad englisch
> Szenario: (ClassLoader)
> WebSphere
> OurServlet
> AXIS
> We redirect AXIS Logging (org.apache.commons.logging.LogFactory) to our own
> logFactory so that we can output messages of AXIS in our own logFiles.
> And we need to prepare service calls for AXIS so all access to AXIS is
> indirected over our own Servlet (OurServlet) which loads AXIS using
> Class.forName().newInstance()
> In WebSphere we get an Exception that AXIS can not load our Logger (AXIS uses
> Commons Discovery)
> The Problem:
> a) WebSphere itself uses Commons Discovery and loads Commons Discovery in the
> ?WebContainer?-ClassLoader. OurServlet and AXIS are loaded in a
> ?Servlet?-ClassLoader ...
> b) Initializing AXIS / AXIS calls DiscoverSingleton.find() which searches for
> the configured logger / but can not find it in the ?WebContainer?-ClassLoader.
> It follows a short java file for testing/demonstrating the problem.
> Additionally
> needed for Test is a Logger Implementation in a single jar File myLogger.jar
> (look at the following source)
> In the code the exception from commons Discovery is given and a solution we
> use
> to solve this problem (but perhaps it is not the recommended way) /
> Can someone who understands the problem tell me how it should bo solved?
> Thanks.
> import java.net.URL;
> import java.net.URLClassLoader;
> import org.apache.commons.discovery.resource.ClassLoaders;
> import org.apache.commons.discovery.tools.DefaultClassHolder;
> import org.apache.commons.discovery.tools.DiscoverSingleton;
> import org.apache.commons.discovery.tools.SPInterface;
> public class ClassLoaderTest
> {
> public static void main( String args[] )throws Exception
> { ClassLoaderTest clt = new ClassLoaderTest();
> clt.problem2();
> }
> static String libPath = "file:// **path** "; // set correct path here !!
>
> public void problem1()throws Exception
> { URL url1[] = new URL[]
> { new URL( libPath+"commons-discovery.jar"),
> new URL( libPath+"commons-logging.jar"),
> new URL( libPath+"servlet.jar")
> };
> ClassLoader parentClassLoader
> = new URLClassLoader( url1, getClass().getClassLoader() );
>
> URL url2[] = new URL[]
> { new URL( libPath+"axis.jar"),
> new URL( libPath+"axis-ant.jar"),
> new URL( libPath+"commons-logging.jar"),
> new URL( libPath+"commons-discovery.jar"),
> new URL( libPath+"log4j-1.2.8.jar"),
> new URL( libPath+"wsdl4j.jar"),
> new URL( libPath+"jaxrpc.jar"),
> new URL( libPath+"xerces.jar"),
> new URL( libPath+"saaj.jar"),
> new URL( libPath+"mylog.jar") // jar with my logger class ...
> };
>
> ClassLoader childClassLoader = new URLClassLoader( url2,
> parentClassLoader );
> System.setProperty
> ( "org.apache.commons.logging.LogFactory"
> , "mylog.MyLogger"
> );
> Class axisServletClass = childClassLoader.loadClass(
> "org.apache.axis.transport.http.AxisServlet" );
> Object axisServlet = axisServletClass.newInstance();
>
> /*
> * Problem: discovery can not load class mylog.MyLogger in mylog.jar
> because
> * it is in another class loader ...
> *
> * AXIS uses DiscoverSingleton.find Method ...
> */
> /*
> java.lang.ExceptionInInitializerError
> at
> org.apache.axis.transport.http.AxisServletBase.<clinit>(AxisServletBase.java:94)
> at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
> at
> sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
> at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
> at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
> at java.lang.Class.newInstance0(Class.java:308)
> at java.lang.Class.newInstance(Class.java:261)
> at ClassLoaderTest.problem(ClassLoaderTest.java:49)
> at ClassLoaderTest.main(ClassLoaderTest.java:13)
> Caused by: org.apache.commons.discovery.DiscoveryException: No
> implementation defined for org.apache.commons.logging.LogFactory
> at
> org.apache.commons.discovery.tools.DiscoverClass.find(DiscoverClass.java:407)
> at
> org.apache.commons.discovery.tools.DiscoverClass.newInstance(DiscoverClass.java:582)
> at
> org.apache.commons.discovery.tools.DiscoverSingleton.find(DiscoverSingleton.java:418)
> at
> org.apache.commons.discovery.tools.DiscoverSingleton.find(DiscoverSingleton.java:378)
> at org.apache.axis.components.logger.LogFactory$1.run(LogFactory.java:84)
> at java.security.AccessController.doPrivileged(Native Method)
> at
> org.apache.axis.components.logger.LogFactory.getLogFactory(LogFactory.java:80)
> at
> org.apache.axis.components.logger.LogFactory.<clinit>(LogFactory.java:72)
> ... 9 more
> */
> }
>
> public void problem2()throws Exception
> { URL url1[] = new URL[]
> { new URL( libPath+"commons-discovery.jar"),
> new URL( libPath+"commons-logging.jar"),
> new URL( libPath+"servlet.jar")
> };
> ClassLoader parentClassLoader
> = new URLClassLoader( url1, getClass().getClassLoader() );
>
> URL url2[] = new URL[]
> { new URL( libPath+"axis.jar"),
> new URL( libPath+"axis-ant.jar"),
> new URL( libPath+"commons-logging.jar"),
> new URL( libPath+"commons-discovery.jar"),
> new URL( libPath+"log4j-1.2.8.jar"),
> new URL( libPath+"wsdl4j.jar"),
> new URL( libPath+"jaxrpc.jar"),
> new URL( libPath+"xerces.jar"),
> new URL( libPath+"saaj.jar"),
> new URL( libPath+"mylog.jar") // jar with my logger class ...
> };
>
> ClassLoader childClassLoader = new URLClassLoader( url2,
> parentClassLoader );
> System.setProperty
> ( "org.apache.commons.logging.LogFactory"
> , "mylog.MyLogger"
> );
>
> Thread.currentThread().setContextClassLoader( childClassLoader );
> Class axisServletClass = childClassLoader.loadClass(
> "org.apache.axis.transport.http.AxisServlet" );
> Object axisServlet = axisServletClass.newInstance();
>
> /*
> * Problem: discovery can not load class mylog.MyLogger in mylog.jar
> because
> * it is in another class loader ...
> *
> * AXIS uses DiscoverSingleton.find Method ...
> */
> /*
> java.lang.ExceptionInInitializerError
> at
> org.apache.axis.transport.http.AxisServletBase.<clinit>(AxisServletBase.java:94)
> at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
> at
> sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
> at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
> at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
> at java.lang.Class.newInstance0(Class.java:308)
> at java.lang.Class.newInstance(Class.java:261)
> at ClassLoaderTest.problem(ClassLoaderTest.java:49)
> at ClassLoaderTest.main(ClassLoaderTest.java:13)
> Caused by: org.apache.commons.discovery.DiscoveryException: No
> implementation defined for org.apache.commons.logging.LogFactory
> at
> org.apache.commons.discovery.tools.DiscoverClass.find(DiscoverClass.java:407)
> at
> org.apache.commons.discovery.tools.DiscoverClass.newInstance(DiscoverClass.java:582)
> at
> org.apache.commons.discovery.tools.DiscoverSingleton.find(DiscoverSingleton.java:418)
> at
> org.apache.commons.discovery.tools.DiscoverSingleton.find(DiscoverSingleton.java:378)
> at org.apache.axis.components.logger.LogFactory$1.run(LogFactory.java:84)
> at java.security.AccessController.doPrivileged(Native Method)
> at
> org.apache.axis.components.logger.LogFactory.getLogFactory(LogFactory.java:80)
> at
> org.apache.axis.components.logger.LogFactory.<clinit>(LogFactory.java:72)
> ... 9 more
> */
> }
> public void solution()throws Exception
> { URL url1[] = new URL[]
> { new URL( libPath+"commons-discovery.jar"),
> new URL( libPath+"commons-logging.jar"),
> new URL( libPath+"servlet.jar")
> };
> ClassLoader parentClassLoader
> = new URLClassLoader( url1, getClass().getClassLoader() );
>
> URL url2[] = new URL[]
> { new URL( libPath+"axis.jar"),
> new URL( libPath+"axis-ant.jar"),
> new URL( libPath+"commons-logging.jar"),
> new URL( libPath+"commons-discovery.jar"),
> new URL( libPath+"log4j-1.2.8.jar"),
> new URL( libPath+"wsdl4j.jar"),
> new URL( libPath+"jaxrpc.jar"),
> new URL( libPath+"xerces.jar"),
> new URL( libPath+"saaj.jar"),
> new URL( libPath+"mylog.jar") // jar with my logger class ...
> };
>
> ClassLoader childClassLoader = new URLClassLoader( url2,
> parentClassLoader );
> // Solution - preLoading Singleton ...
> Thread.currentThread().setContextClassLoader( childClassLoader );
> Class myLog = childClassLoader.loadClass( "mylog.MyLogger" );
> DefaultClassHolder defaultClassHolder = new DefaultClassHolder( myLog );
>
> Class loggerInterface = childClassLoader.loadClass(
> "org.apache.commons.logging.LogFactory" );
>
> ClassLoaders classLoaders = new ClassLoaders();
> classLoaders.put( childClassLoader );
> Object o = DiscoverSingleton.find
> ( classLoaders, new SPInterface(loggerInterface), null,
> defaultClassHolder
> );
>
> // AXIS now loads the correct logger singleton ...
> Class axisServletClass = childClassLoader.loadClass(
> "org.apache.axis.transport.http.AxisServlet" );
> Object axisServlet = axisServletClass.newInstance();
> }
> }
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