René Nyffenegger's collection of things on the web | |
René Nyffenegger on Oracle - Most wanted - Feedback
- Follow @renenyffenegger
|
web.xml | ||
The web.xml file defines each servlet and JSP page within a Web Application. It also enumerates
enterprise beans referenced in the Web application.
The file goes into the WEB-INF directory under the document root of a
web application.
A sample web.xml
This xml file is alls called deployment descriptor.
<?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd"> <web-app> <display-name> The name of the application </display-name> <description> C'mon, you know what goes into a description, don't you? </description> <context-param> <param-name>name_of_context_initialization_parameter</param-name> <param-value>value_of_context_initializtion_parameter</param-value> <description> Again, some description </description> </context-param> <servlet> <servlet-name>guess_what_name_of_servlet</servlet-name> <description>Again, some description</description> <servlet-class>com.foo-bar.somepackage.TheServlet</servlet-class> <init-param> <param-name>foo</param-name> <param-value>bar</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>name_of_a_servlet</servlet-name> <url-pattern>*.some_pattern</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>image</servlet-name> <url-pattern>/image</url-pattern> </servlet-mapping> <session-config> <session-timeout>30</session-timeout> </session-config> </web-app> context-param
The values within the context-param element can be accessed like so:
String value = getServletContext().getInitParameter("name_of_context_initialization_parameter");
Servlet initialization parameters (that is: the values within the servlet element)
can be retrieved in a servlet or JSP page by calling:
String value = getServletConfig().getInitParameter("foo"); session-timeout
<session-timeout>: The timeout for a session in minutes.
servlet
For each servlet in the web application, there is a <servlet> element. The name
identifies the servlet (<servlet-name>).
servlet-mapping
Each servlet in the web application gets a servlet mapping. The url pattern is used to map
URI to servlets.
Obviously, the order of the elements matters!
|