For the ServletContext initialization parameters: write servlet
code to access
initialization parameters; and create the deployment descriptor elements for declaring
initialization parameters.
The following methods of the ServletContext interface allow the
servlet access to context initialization parameters associated with a Web application
as specified by the Application Developer in the deployment descriptor:
getInitParameter
Returns a String containing the value of the named
context-wide initialization parameter, or null if the
parameter does not exist. This method can make available configuration information
useful to an entire "web application". For example, it can provide a
webmaster’s email address or the name of a system that holds critical data.
getInitParameterNames
Returns the names of the context's initialization parameters as an
Enumeration of String objects, or
an EMPTY Enumeration if the context has NO initialization
parameters.
public interface ServletContext {
public java.lang.String getInitParameter(java.lang.String name);
public java.util.Enumeration getInitParameterNames();
}
Context initialization parameters that define shared
String constants used within your application, which
can be customized by the system administrator who is
installing your application. The values actually
assigned to these parameters can be retrieved in a
servlet or JSP page by calling:
javax.servlet.ServletContext context = getServletContext();
String value = context.getInitParameter("webmaster");
where "webmaster" matches the param-name element of
one of these initialization parameters.
You can define any number of context initialization parameters, including zero:
<web-app>
...
<context-param>
<param-name>webmaster</param-name>
<param-value>myaddress@mycompany.com</param-value>
<description>
The EMAIL address of the administrator to whom questions
and comments about this application should be addressed.
</description>
</context-param>
...
</web-app>
<!--
The context-param element contains the declaration of a web
application’s servlet context initialization parameters.
-->
<!ELEMENT context-param (param-name, param-value, description?)>
