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Avi Kak

Through the servlet-mapping element of the webapp deployment descriptor file web.xml. The url-pattern sub-element of the servlet-mapping element must be set to '/'.

If made available, a default servlet is executed by the server whenever the client browser points to the URL

       http://foo.com/mywebapp/

or to the URL

       http://foo.com/mywebapp/nonExistentServlet

For example, for a webapp named test-suite, the deployment descriptor shown below permits my server to execute the DefaultHelloServlet for the following URLs:

       http://localhost:8080/test-suite/

       http://localhost:8080/test-suite/NonExistentServlet

for any pathname substituted for NonExistentServlet provided it does not begin with /servlet/.

Here is the deployment descriptor (web.xml) for this example that sits in the WEB-INF directory of my test-suite webapp:

<?xml version="1.0"?>

<!DOCTYPE web-app SYSTEM
+"http://java.sun.com/j2ee/dtds/web-app_2.2.dtd">

<web-app>
       
    <servlet>
        <servlet-name>
            hello
        </servlet-name>
        <servlet-class>
            DefaultHelloServlet
        </servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>
            hello
        </servlet-name>
        <url-pattern>
            /
        </url-pattern>
    </servlet-mapping>
       
</web-app>

See also Alex Chaffee's Servlet FAQ entry dealing with servlet aliasing.