I have a Java (6) application which uses Hibernate (V3.3.2) to read data from HSQLDB, which i build and debug/run with Eclipse (V3.5.1), and it works fine.
I then created a GWT (V1.7) Servlet web app, copied my hibernate classes into it, and added the same User Libraries dependencies. However when i run the servlet and try to access a URL which invokes my code i get this:
java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
at org.hibernate.cfg.Configuration.<clinit>(Configuration.java:152)
at xxx.daoimpl.DAOSession.initialise(DAOSession.java:40)
where DAOSession.java:40 is :
AnnotationConfiguration config = new AnnotationConfiguration ();
Googling for this error suggests i am missing slf4j-api.jar from the classpath, however if i look at the command line for the Debug properties i can see this jar there:
C:\java\jsedk_6\jre\bin\javaw.exe
-agentlib:jdwp=transport=dt_socket,suspend=y,address=localhost:54541
-Xmx512m -Dfile.encoding=Cp1252
-classpath
D:\dev\workspace\xxx\src;
D:\dev\workspace\xxx\resources;
D:\dev\workspace\xxx\war\WEB-INF\classes;
C:\java\eclipse\plugins\com.google.gwt.eclipse.sdkbundle.win32_1.7.1.v200909221731\gwt-windows-1.7.1\gwt-user.jar;
C:\java\eclipse\plugins\com.google.gwt.eclipse.sdkbundle.win32_1.7.1.v200909221731\gwt-windows-1.7.1\gwt-dev-windows.jar;
C:\java\hibernate-annotations-3.4.0.GA\hibernate-annotations.jar;
C:\java\hibernate-annotations-3.4.0.GA\lib\ejb3-persistence.jar;
C:\java\hibernate-annotations-3.4.0.GA\lib\hibernate-commons-annotations.jar;
C:\java\hibernate-distribution-3.3.2.GA\hibernate3.jar;
C:\java\hibernate-distribution-3.3.2.GA\lib\required\antlr-2.7.6.jar;
C:\java\hibernate-distribution-3.3.2.GA\lib\required\commons-collections-3.1.jar;
C:\java\hibernate-distribution-3.3.2.GA\lib\required\dom4j-1.6.1.jar;
C:\java\hibernate-distribution-3.3.2.GA\lib\required\javassist-3.9.0.GA.jar;
C:\java\hibernate-distribution-3.3.2.GA\lib\required\jta-1.1.jar;
C:\java\hibernate-validator-4.0.1.GA\hibernate-validator-4.0.1.GA.jar;
C:\java\hibernate-validator-4.0.1.GA\lib\validation-api-1.0.0.GA.jar;
C:\java\hibernate-validator-4.0.1.GA\lib\log4j-1.2.14.jar;
C:\java\hsqldb\lib\hsqldb.jar;
C:\java\restlet-jse-2.0m5\lib\org.restlet.jar;
C:\java\restlet-jee-2.0m5\lib\org.restlet.ext.servlet.jar;
C:\java\restlet-jse-2.0m5\lib\org.restlet.ext.xml.jar;
C:\java\slf4j-1.5.8\slf4j-api-1.5.8.jar;
C:\java\slf4j-1.5.8\slf4j-log4j12-1.5.8.jar
com.google.gwt.dev.HostedMode
...
If i open the jar i can see the LoggerFactory class in there.
Any idea why it isn't being found by the class loader?
Edit 1: If try to access org.slf4j.LoggerFactory from my code, Eclipse compiles it ok, but i get the same error at runtime.
Edit 2: If i add a Test class with a main which calls the same code and run it, it works. So this classpath problem seems specific to the Servlet.
thanks, jon
It seems that copying the two slf4j jars to the war/WEB-INF/lib sub-project/dir fixed the problem. I'm not really sure why i should need to do this for these two jars and not for all the other Hibernate, Restlet etc jars that the project also uses, though i suppose for consistency i will do that anyway - i guess it will make deployment easier as well.
If someone can provide some sort of explanation as to why this worked and why exactly i need to do it i will select it as the "correct" answer, otherwise i'll select this one.
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