SchemaTool() throws ClassNotFoundException: oracle.jdbc.driver.OracleDriver

Question

KODO 2.5.3
I am trying to use the SchemaTool java class for schema manipulations. When
I try to construct a SchemaTool object I get the following exception:
com.solarmetric.kodo.runtime.FatalUserException:
java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
NestedThrowables:
java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
I am passing an instance of MultiLoaderClassResolver (constructed using a
custom URLClassLoader) as the ClassResolver argument to the SchemaTool
constructor. The orcale jar "classes12.jar" is one of the URLs in the
URLClassResolver. Before constructing a SchemaTool object, a call to
canResolveClass("oracle.jdbc.driver.OracleDriver") on the class resolver
returns true. So why is SchemaTool not able to find this class?
Thanks
Vijay

Answer 1

Marc,
It might well be problems with my custom class loader (which are a pain to
debug indeed) or my lack of understanding of some of your schema tool
classes, but the basic problem I encountered (before getting to the Logger
issue) is as follows:
I have an instance of MultiLoaderClassResolver constructed using my custom
class loader.
A call to resolveClass("orcale.jdbc.driver.OrcaleDriver") on this instance
returns the correct Class (does not throw a ClassNotFound exception).
The same MultiLoaderClassResolver instance is passed as an argument to
SchemaTool(). SchemaTool.refresh() throws an exception:
ClassNotFound: orcale.jdbc.driver.OrcaleDriver
So it seems to me that somewhere in the SchemaTool code you are trying to
resolve orcale.jdbc.driver.OrcaleDriver using something other than the
instance of MultiLoaderClassResolver that I passed in. From the stack trace
in my earlier message, it seems like that is happening in:
com.solarmetric.kodo.impl.jdbc.ormapping.ClassMapping.createPKColumns(ClassM
apping.java:1584)where an instance of ConfigurationConnector is constructed. BTW, this is how
I construct and pass a ConfigurationConnector to SchemaTool:
JDBCConfiguration conf = new JDBCSimpleConfiguration(someProps);
ClassResolver resolver = new MultiLoaderClassResolver(myCustomClassLoader);
Connector connector = new ConfigurationConnector(conf, resolver, false);
SchemaTool sTool = new SchemaTool(conf, resolver, connector);
Vijay
"Marc Prud'hommeaux" <[email protected]> wrote in message
news:[email protected]...
Vijay-
Custom ClassLoader problems are often very hairy to debug. The first
error message you are receiving indicates a problem:
org.apache.commons.logging.LogConfigurationException: Class
org.apache.commons.logging.impl.Log4JLogger does not implement LogThis indicates to me that the
"org.apache.commons.logging.impl.Log4JLogger" and
"org.apache.commons.logging.Log" classes are being loaded in different
ClassLoaders, which is generally a bad thing. Is your URLClassLoader
deferring to the parent ClassLoader?
I think that the first step is to identify why the class loaders are
different for these two classes (which should be easy to do with some
printlns in a test program that uses your URLClassLoader).
Bear in mind that this isn't technicall a Kodo issue, but a general
ClassLoader issue. However, we are happy to try to provide hints and
guidance about how to isolate the source of the problem.
In article <[email protected]>, Vijay Ganesan wrote:
After trying out some combinations, the stack trace at the bottom of
this
message gives a better clue of what my problem is:
Looks like a new ConfigurationConnector is created in ClassMapping.javathat
ignores my class resolver (based on my custom class loader) that Icreated
as follows:
JDBCConfiguration conf = new JDBCSimpleConfiguration(someProps);
ClassResolver resolver = newMultiLoaderClassResolver(myCustomClassLoader);
>>
Connector connector = new ConfigurationConnector(conf, resolver, false);
SchemaTool sTool = new SchemaTool(conf, resolver, connector);
Adding the following line before the schema related code solves theproblem:
Thread.currentThread().setContextClassLoader(myCustomClassLoader);
However, that causes another error which, from a brief look at
LogFactoryImpl, seems surely related to custom class loaders. Don't knowhow
to get past this one:
org.apache.commons.logging.LogConfigurationException:
org.apache.commons.logging.LogConfigurationException:
org.apache.commons.logging.LogConfigurationException: Class
org.apache.commons.logging.impl.Log4JLogger does not implement Log
at
org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.ja
va:532)
at
org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.ja
va:272)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:414)
at
com.solarmetric.kodo.impl.jdbc.runtime.ConfigurationConnector.createConnecti
onFactory(ConfigurationConnector.java:140)
--------Stack trace------------
java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
at
com.solarmetric.util.classes.LoaderClassResolver.resolveClass(LoaderClassRes
olver.java:34)
at
com.solarmetric.kodo.impl.jdbc.runtime.ConfigurationConnector.createConnecti
onFactory(ConfigurationConnector.java:113)
at
com.solarmetric.kodo.impl.jdbc.runtime.ConfigurationConnector.<init>(Configu
rationConnector.java:67)
at
com.solarmetric.kodo.impl.jdbc.runtime.ConfigurationConnector.<init>(Configu
rationConnector.java:59)
at
com.solarmetric.kodo.impl.jdbc.runtime.ConfigurationConnector.<init>(Configu
rationConnector.java:39)
at
com.solarmetric.kodo.impl.jdbc.ormapping.ClassMapping.createPKColumns(ClassM
apping.java:1584)
at
com.solarmetric.kodo.impl.jdbc.ormapping.ClassMapping.install(ClassMapping.j
ava:1416)
at
com.solarmetric.kodo.impl.jdbc.ormapping.Mapping.createMapping(Mapping.java:
169)
at
com.solarmetric.kodo.impl.jdbc.ormapping.Mapping.createMappings(Mapping.java
:116)
at
com.solarmetric.kodo.impl.jdbc.ormapping.Mapping.createMappings(Mapping.java
:86)
at
com.solarmetric.kodo.impl.jdbc.schema.SchemaTool.createMappings(SchemaTool.j
ava:831)
at
com.solarmetric.kodo.impl.jdbc.schema.SchemaTool.refresh(SchemaTool.java:333
at
com.solarmetric.kodo.impl.jdbc.schema.SchemaTool.refresh(SchemaTool.java:321
at
com.solarmetric.kodo.impl.jdbc.schema.SchemaTool.refresh(SchemaTool.java:311
"Stephen Kim" <[email protected]> wrote in message
news:[email protected]...
My guess is that your custom classloader is preventing instanceof. Can
you try using the system classloader or see if java.sql.Driver is
assignable from oracle.jdbc.dirver.OracleDriver?
Vijay Ganesan wrote:
KODO 2.5.3
I am trying to use the SchemaTool java class for schema
manipulations.
When
I try to construct a SchemaTool object I get the following exception:
com.solarmetric.kodo.runtime.FatalUserException:
java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
NestedThrowables:
java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
I am passing an instance of MultiLoaderClassResolver (constructed
using
a
custom URLClassLoader) as the ClassResolver argument to the
SchemaTool
constructor. The orcale jar "classes12.jar" is one of the URLs in the
URLClassResolver. Before constructing a SchemaTool object, a call to
canResolveClass("oracle.jdbc.driver.OracleDriver") on the classresolver
returns true. So why is SchemaTool not able to find this class?
Thanks
Vijay
Steve Kim
[email protected]
SolarMetric Inc.
http://www.solarmetric.com
Marc Prud'hommeaux [email protected]
SolarMetric Inc. http://www.solarmetric.com