deploye/builde war fil på Tomcat 5.5 - f ejl

jeg har følgende filstruktur:
TOMCAT:

C:\Programmer\Tomcat 5.5\common\lib

C:\SWA\jspbook\WEB-INF\web.xml
C:\SWA\jspbook\WEB-INF\classes\hello\HelloWorldServlet.java
C:\SWA\jspbook\WEB-INF\lib

C:\SWA\jspbook\build.xml

Min servlet.

package hello;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.net.*;
import java.util.*;

public class HelloWorldServlet extends HttpServlet
{
  ...
}

Og jeg har følgende build fil:

<?xml version="1.0" ?>
<project name="jspbook" default="compile" basedir=".">
  <target name="compile">
    <javac
      srcdir="WEB-INF/classes"
      extdirs="WEB-INF/lib:../../common/lib"
      classpath="../../common/lib/servlet.jar"
      deprecation="yes"
      verbose="no">
      <include name="hello/**"/>
    </javac>
  </target>
</project>

Det virker ikke får følgende fejl. Jeg står i direktoratet
c:\SWA\jspbook, når jeg prøver at builde

C:\SWA\jspbook>ant
Buildfile: build.xml

compile:
    [javac] Compiling 1 source file
    [javac] C:\SWA\jspbook\WEB-INF\classes\hello\HelloWorldServlet.java:3: packa
ge javax.servlet does not exist
    [javac] import javax.servlet.*;
    [javac] ^
    [javac] C:\SWA\jspbook\WEB-INF\classes\hello\HelloWorldServlet.java:4: packa
ge javax.servlet.http does not exist
    [javac] import javax.servlet.http.*;
    [javac] ^
    [javac] C:\SWA\jspbook\WEB-INF\classes\hello\HelloWorldServlet.java:9: canno
t resolve symbol
    [javac] symbol  : class HttpServlet
    [javac] location: class hello.HelloWorldServlet
    [javac] public class HelloWorldServlet extends HttpServlet
    [javac]                                        ^
    [javac] C:\SWA\jspbook\WEB-INF\classes\hello\HelloWorldServlet.java:11: cann
ot resolve symbol
    [javac] symbol  : class HttpServletRequest
    [javac] location: class hello.HelloWorldServlet
    [javac]    public void doGet(HttpServletRequest request, HttpServletRespons
e response)throws ServletException, IOException
    [javac]                      ^
    [javac] C:\SWA\jspbook\WEB-INF\classes\hello\HelloWorldServlet.java:11: cann
ot resolve symbol
    [javac] symbol  : class HttpServletResponse
    [javac] location: class hello.HelloWorldServlet
    [javac]    public void doGet(HttpServletRequest request, HttpServletRespons
e response)throws ServletException, IOException
    [javac]                                                  ^
    [javac] C:\SWA\jspbook\WEB-INF\classes\hello\HelloWorldServlet.java:11: cann
ot resolve symbol
    [javac] symbol  : class ServletException
    [javac] location: class hello.HelloWorldServlet
    [javac]    public void doGet(HttpServletRequest request, HttpServletRespons
e response)throws ServletException, IOException
    [javac]
                  ^
    [javac] 6 errors