Java Web server display images from file system?

I am developing a web application which collects data every day and shows data visualisation images on the web pages.My web server is Tomcat. Now it can collect data and import data into MySQL. Then it generates visualisation images based on the given data using JFreeChart library and exports the images to local file system. For example I export the images to folders like "C:/hdsdata/2016-01-01/". But I don't know how to display the generated images on the web pages. I can only show visualisation images under the war directory not a file system directory. Or I don't know how to export visualisation images to the war directory.