Servlet Development Guide : PART III Programming : Chapter 6 The Servlet API : Reading Context Parameters
Reading Context Parameters
Every servlet and filter in a context has access to the context parameters defined in the context web.xml file. The context object provides a getInitParameter() function that takes a std::string name and returns the contents of the initialization parameter by that name. The code sample below shows a servlet retrieving the initialization parameters from the context-param element shown in “Set Context Parameters”
 
std::string message =
getServletContext().getInitParameter("message");
If the context does not contain a context parameter with the name provided, the getInitParameter() function returns an empty string.