How to copy properties from one object to another?

I am implementing a audit service and I want to copy properties of the auditing object to the log object. The log object contains the same properties as the auditing object and some additional properties like timestamp, modifiedBy etc. I want to copy the common properties from the auditing object to log object. I tried with reflection but it allows copy only for similar type of objects. How to do this? Is there a way to use reflection with xml file mapping? I'm using java by the way