Different between ServleConfig and ServletContext

Many servlet’s developers are confuse about the different between “ServletConfig” and “ServletContext”. Actually the “ServletContext” name is quite confusing, it should change to “AppConfig” or “AppContext” in the future release 🙂

ContextConfig

1) This is one per “web application”, access globally by all the servlets’ class
2) web.xml – within the web-app element and outside the servlet element

    <web-app ...>
        <servlet>
		<servlet-name>ServletName</servlet-name>
		<servlet-class>com.mkyong.ServletDemo</servlet-class>
	</servlet>
	
	<context-param>
			<param-name>email</param-name>
			<param-value>[email protected]</param-value>
	</context-param>
   </web-app>

3) Servlet code

getServletContext().getInitParameter("email")

==> See the ServletContext example here

ServletConfig

1) This is one per “servlet”, only access for each specific servlet
2) web.xml – within the servlet element

    <web-app ...>
        <servlet>
		<servlet-name>ServletName</servlet-name>
		<servlet-class>com.mkyong.ServletDemo</servlet-class>

                 <init-param>
			<param-name>email</param-name>
			<param-value>[email protected]</param-value>
	         </init-param>

	</servlet>
   </web-app>

3) Servlet code

getServletConfig().getInitParameter("email")

==> See the ServletContext example here