Howto generate Hibernate POJO and mapping files dynamically

Question

Hi Actually we are using custom table which will contain different columns for different clients so i want to generate Hibernate Mapping file and corresponding POJO at application deployment time.

There are two solutions which i have already read on this forum are.

1. using ant task in build.xml

2. or using ant class file in my code for generating this stuff.

   so my questions are,

   Q1.is there any other solution to this problem

   Q2.if not,then which is best approach from above solutions.

Thanks in advance.