It sounds to me that you need to do an XSLT transformation to convert your XML into an HTML fragment which can be placed in your web page by your JSP.
Your oringinal question was for open source tools, so you probably need an open source XSLT processor (such as saxon or xalan). Depending on which container you are using, it may make XSLT processing services available to your application already.
If you are unfamiliar with XSLT, you may like to try an XSLT
IDE for experimentation to generate your XSLT transformation script. Personally I have always developed my XSLT in a regular text editor, but that can be scary and frustrating.