Generic report framework using struts and ibatis

We are working on a new internal project to develop a report screen , the user using this web application, uses the generated csv or excel file for their analysis.this report is configurable such that SQL query and all the inPut parameters are given thru web app. Later the report framework should execute this SQL along with input parameters supplied. Normally report generated contains 500k rows max and needs to be exported to csv or excel. I needed some best suggestion on following questions.

1. do in need to use API such as (Apache POI开发者_如何学编程 or csv writer ) or just the get result set and append to string buffer write to output stream directly.
2. Since I am using ibatis , is there any better or efficient way to retrieve 500k rows thru ibatis (any API 's), write it to csv or excel with/without generating file at the server end.
3. Any other alternative suggestions .

Thank u all.

We are doing the same thing in our application. We are using Struts and the list retrieved from iBatis is passed to 'Jasper Reports' for report generation. http://struts.apache.org/2.0.11.2/docs/jasperreports-tutorial.html

Jasper Reports gives the flexibility to render reports in any report with minimal coding.