Step1:
Create java class and create jar file from it.
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| SampleJava.java |
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| Test.jar |
Step2:
Import jar file in classpath(with export option selected) and using java embedding invoke java method.
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| Test_Java_BPEL.zip |
Step3:
It may happen successful compilation but failure to deploy code.In such case add the jar file under $Application/SCA-INF/lib folder.
Step4:
To add custom jar in classpath check below link. Probably this will be required if jar is not exported and will be required in server runtime.