At run time how can we change the database ad deails?
I agree with Hozawa, that by default Jasper does not support dynamic connnections. but if you can write some scriptlets
Check Default Data adapters
When Default data adapter configuration is mentioned, the report will try to connect to a database using the configuration given in a default data adapter.
For configuring default data adapter on a report, you would write up a database config xml file and place that on the Root level of Jasper server
I'm just throwing an idea:
May be you could write a scriptlet based on a parameter and update this default data adapter Configuration file on the server dynamically (but by no means this is secure since the configuration file carries unhashed username/password for the data adapter).