JDK, whatever its version is, contains only
"core" java library classes. Servlet, JSP, EJB, JMS, JTS, .... consists in the so-called J2EE.
Servlet and JSP package come by two different ways: 1) Java Servlet Development Kid(JSDK, servlet.jar); or 2) Java 2 Enterprise Edition(J2EE, j2ee.jar). Since you are working on Servlet, you need to download either of them. Go to java.sun.com and browse its API.