Servlet as a welcome file: is it a myth?

Question

Hello
There are many articles on the web that espouse that Servets 2.4 allow for a servlet to be specified as a welcome file thusly (taken from OnJava.com):
First, register the servlet in web.xml.
<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=
"http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">
<servlet>
<servlet-name>MyServlet</servlet-name.
<servlet-class>com.jspservletcookbook.MyServlet</servlet-class>
</servlet>
<!-- optionally map the 'MyServlet' servlet to a URL pattern -->
<servlet-mapping>
<servlet-name>MyServlet</servlet-name>
<url-pattern>/myservlet</url-pattern>
</servlet-mapping>
<!-- rest of web.xml ... -->
Then create a welcome-file element in web.xml that specifies the registered servlet name.
<welcome-file-list>
<welcome-file>MyServlet</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
Make sure to use the servlet name in the welcome-file element without a forward slash (/) preceding it.
Poppycock I say. At least it's not working for me with either Tomcat 5 or Tomcat 5.5. Has anyone out there ever seen this work on Tomcat?

Answer 1

It most certainly is possible now, but wasn't until rather late in TC 5.0.xx series I believe (5.0.18 or so?). You can chack the change logs to id exactly when...
But the reason it isn't working for you is you have to match the value in your <welcome-file> to the URL in the servlet's <url-pattern> servlet mapping. So your web XML should look like this:
<servlet>
  <servlet-name>MyServlet</servlet-name.
  <servlet-class>com.jspservletcookbook.MyServlet</servlet-class>
</servlet>
<servlet-mapping>
  <servlet-name>MyServlet</servlet-name>
  <url-pattern>/myservlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
  <welcome-file>myservlet</welcome-file>
  <welcome-file>default.jsp</welcome-file>
</welcome-file-list>Your porblem was case. Your url-pattern had lower case, but the welcome-file had upper case letters like the servlet name.
Here is an example app that I tested and worked:
//The servlet:
package net.thelukes.steven;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class WelcomeServlet extends HttpServlet {
     public void doGet(HttpServletRequest request, HttpServletResponse response)
       throws ServletException, IOException {
          PrintWriter out = response.getWriter();
          out.println("Hello World");
          out.flush();
          out.close();
//the web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4"
         xmlns="http://java.sun.com/xml/ns/j2ee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
                             http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
     <display-name>WTPTest</display-name>
     <servlet>
          <servlet-name>Welcome</servlet-name>
          <servlet-class>net.thelukes.steven.WelcomeServlet</servlet-class>
     </servlet>
     <servlet-mapping>
          <servlet-name>Welcome</servlet-name>
          <url-pattern>/welcome</url-pattern>
     </servlet-mapping>
     <welcome-file-list>
          <welcome-file>welcome</welcome-file>
     </welcome-file-list>
</web-app>
//The address I typed (the web app is names WTPTest
http://localhost:8080/WTPTest
//The HTML Output
Hello World