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You are not deploying the oracle driver with the application. Place the driver jars in a shared or library extension folder of your application server. (You should go with option one or two though
A few things cause this exception:
1) Check if you have all jars and if they're in the correct path.
2) Your classpath might be broken, you can define it in the command line with
java -cp yourClassPathor at your IDE if you're using one.
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