From http://javaevangelist.blogspot.com/2012/11/servlet-30-tip-how-do-i-get-to-another.html

servlet30ContextTip.java

//Substitute your target web application below.  
ServletContext sc = request.getServletContext().getContext("/EnterpriseApplication1-war"); 
//An example of what you can see to prove a point 
Map<String, ? extends ServletRegistration> map = sc.getServletRegistrations(); 
for (String key : map.keySet()) {    
    sc.log("Registration " + map.get(key).getName());      
    Map<String, String> params = sc.getServletRegistration(map.get(key).getName()).getInitParameters();    
    for (String k : params.keySet()) {        
        sc.log("\t" + k + " --> " + params.get(k));
    }
}