It is a Java servlet implements proxy for Google Chart. Servlet requests Google Chart and caches the generated image. So all the sub-sequent requests will be served right from your own site. It lets you keep Google Charts limit (50 000 requests per user) and improve the performance.
How to use it:
a) copy chartPackage.jar into your WEB-INF/lib directory.
b) define ChartServlet in your web.xml file. You can set the following initial parameters:
dir - Describes an existing directory on your server for the saved content
proxyHost - Optional parameter. Describes a proxy host for your internet connection
proxyPort - Optional parameter. Describes a proxy port for your internet connection
expires - Optional parameter. This parameter describes a caching time (in seconds)
for the images (client side cache).
For example:
<servlet>
<servlet-name>ChartServlet</servlet-name>
<servlet-class>com.jsos.chart.GoogleChart</servlet-class>
<init-param>
<param-name>dir</param-name>
<param-value>/home/dump</param-value>
</init-param>
</servlet>
c) define a mapping for ChartServlet:
<servlet-mapping>
<servlet-name>ChartServlet</servlet-name>
<url-pattern>/servlet/chart</url-pattern>
</servlet-mapping>
For the charts generation parameters see Google Charts API. Servlets obviously uses the same set of parameters. E.g.:
/servlets/chart?cht=p3&chd=t:60,40&chs=250x100&chl=Hello|World
For downloading: chartPackage.jar
See also JSOS - the largest collection of servlets and filters.