problems loading the driver within a jar

[Andy Jung]

Hi all,

Want to load a DB2 Driver within an executable jarfile. The following statements all work if not jared, but don't if they are to be executed within a jar (ClassNotFoundException):

   
Class.forName("com.ibm.db2.jcc.DB2Driver");

   
getClass().getClassLoader().loadClass("com.ibm.db2.jcc.DB2Driver");

What's the solution to this? Do I need a special ClassLoader for the jar?

Kind regards,
Andy

[Paul Sturrock]

That's not how Jar files work. You can't package Jars inside Jars. Try shipping the driver with your Jar file not in it.

(NB: if this is the DB2 driver you are probably breaking its licence - from memory I don't think you can distribute it).

[Andy Jung]

sorry, I didn't express myself correctly.
The jarfile, where the driver is located, is outside my jar of course. However the Java statement, which is to load the driver is inside my jar.

[Paul Sturrock]

Yes, you'll need a Class-Path instruction in your Jar file.

[Andy Jung]

... isn't it already sufficient to invoke my jar (ts.jar) with -cp option where the classpath is specified?
All the libraries are located under $TAPAS_HOME/lib/ .

...
TS_CLASSPATH=$TAPAS_HOME/lib/
for i in $TAPAS_HOME/lib/*.jar; do
     TS_CLASSPATH=$i:$TS_CLASSPATH
done

# perform property - transformation:
$JAVA_HOME_5/java -cp $TS_CLASSPATH $TAPAS_HOME/lib/ts.jar -i
...

Nevertheless, the classpath is also resolved in the manifest-file as follows:

    
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.7.0
Created-By: 1.5.0_19-b02 (Sun Microsystems Inc.)
Built-By: Andreas Jung
Main-Class: osplus.icm.TapasServiceStarter
Class-Path: ./lib/com.ibm.mq.jar ./lib/com.ibm.mq.jms.Nojndi.jar ./l
 ib/com.ibm.mqjms.jar ./lib/db2jcc.jar ./lib/db2jcc_license_cu.jar ./lib/dhb
 core.jar ./lib/jms.jar

[Paul Sturrock]

Andy Jung wrote:... isn't it already sufficient to invoke my jar (ts.jar) with -cp option where the classpath is specified?
All the libraries are located under $TAPAS_HOME/lib/ .

It is. But if you want the jar to be executable you would use the Class-Path entry (easier for the end user).