I posted some notes a couple weeks ago about .NET configuration files, came across the code for doing the same thing in a servlet container tonight. Basically, you get a ServletConfig object using the getServletConfig() method of the Servlet interface and then call getInitParameter(String initParamName) on that. For example, let’s say that I put a global database connection string in my web.xml deployment descriptor:

<web-app>
  <servlet>
   <servlet-name>myservlet</servlet-name>
   <servlet-class>MyServlet</servlet-class>
    <init-param>
     <param-name>connection_string</param-name>
     <param-value>user id=sa;password=mypassword;initial catalog=mydb;data source=mydbserver;Connect Timeout=30</param-value>
    </init-param>
  </servlet>
</web-app>

Then, in my servlet code init() method, I could write this:

ServletConfig sc = getServletConfig();
String connection_string = sc.getInitParameter(“connection_string”);

After retrieving the value from the ServletConfig object, you’ll probably want to store it for later use in the ServletContext object:

ServletContext c = getServletContext();
c.setAttribute(“connection_string”, connection_string);

Now I can get the connection string in a JSP or a servlet later using this short snippet:

String myCS = (String)getServletContext().getAttribute(“connection_string”);