How do I define an environment variable that can be accessed in all servlets in a Web application ?

A J2EE application may require one or more initialization parameters to be accessed by one or more servlets in a web application. An initialization parameter be for a context or for a specific servlet. The context level parameters can be accessed by any servlets in the web application.

a) To define a context parameter you have to add in the following in the web.xml as follows:

<context-param>
  <param-name>filedir</param-name>
  <param-value>/temp</param-value>
</context-param>

b)You have to use context.getInitParameter method to get the Context level parameter as in the following code:

javax.servlet.ServletContext context = getServletContext();
String fileDir = context.getInitParameter("filedir");