There are a few ways of doing this:
1) Bar chart: Create a BIG table of cells that span certain number of columns/rows (bad Bad BAD) Rather not
2) The kewlest way (I think) is to generate an image using
java's image tools and actually draw whatever chart you want programmatically. Create a
servlet that does this, and simply streams the image to the browser.
In your page, just set the images' url to the sevlet (you can pass parameters in the url, if you want)
This way, you can instruct the image to reload using javascript, without having to reload the page.