How to run java servlet without using Web.xml?

Question

How to run servlet without using Web.xml? From a book, I know that web.xml descriptor is optional, but the book doesn't tell us how to run java servelet without web.xm descriptor. So how to do that? Thanks a lot.

Answer 1

How to run servlet without using Web.xml?But Tomcat now uses a web.xml for its global server-wide configuration.
If you'd like to invoke a servlet with:
http://host/servlet/ServletName
you have to enable the invoker servlet.
[from an HTML]
  <FORM METHOD="POST" ACTION="/servlet/HGrepSearchSJ">
[from resin.conf of Resin Web Server 2.1.12]
  <!--
     - The "invoker" servlet invokes servlet classes from the URL.
     - /examples/basic/servlet/HelloServlet will start the HelloServlet
     - class.  In general, the invoker should only be used
     - for development, not on a deployment server, because it might
     - leave open security holes.
    -->
  <servlet-mapping url-pattern='/servlet/*' servlet-name='invoker'/>
[from TOMCAT5.0.19/conf/web.xml, a global server-wide web.xml file]
  <!-- The "invoker" servlet, which executes anonymous servlet classes      -->
  <!-- that have not been defined in a web.xml file.  Traditionally, this   -->
  <!-- servlet is mapped to URL pattern "/servlet/*", but you can map it    -->
  <!-- to other patterns as well.  The extra path info portion of such a    -->
  <!-- request must be the fully qualified class name of a Java class that  -->
  <!-- implements Servlet (or extends HttpServlet), or the servlet name     -->
  <!-- of an existing servlet definition.     This servlet supports the     -->
  <!-- following initialization parameters (default values are in square    -->
  <!-- brackets):                                                           -->
  <!--                                                                      -->
  <!--   debug               Debugging detail level for messages logged     -->
  <!--                       by this servlet.  [0]                          -->
    <servlet>
        <servlet-name>invoker</servlet-name>
        <servlet-class>
          org.apache.catalina.servlets.InvokerServlet
        </servlet-class>
        <init-param>
            <param-name>debug</param-name>
            <param-value>0</param-value>
        </init-param>
        <load-on-startup>2</load-on-startup>
    </servlet>
---comment out below----------------------------------------------------------
    <!-- The mapping for the invoker servlet -->
<!--
    <servlet-mapping>
        <servlet-name>invoker</servlet-name>
        <url-pattern>/servlet/*</url-pattern>
    </servlet-mapping>
-->