This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
You need to draw your graph with whatever you like, and find library that will convert your graph to gif, jpeg or png. Actually I used servlet to draw, convert and serve the image, and in the JSP include it as: