To setup a private export server in Java, you will need the official J2EE export handler provided in the FusionCharts package. The export handler will provide the necessary files to configure the export server. It will handle all requests sent by the user for exporting and generate the chart in the requested format.
The J2EE export handler is dependent on two external modules, namely, Inkscape and ImageMagick. These two need to be downloaded and installed separately on the same server.
For detailed steps follow the documentation here.