Books

Core Java 

• A Programmer's Guide to Java Certification: A Comprehensive Primer, Volume 1 By Khalid Azim Mughal, Rolf W.
• Head First Java By Kathy Sierra, Bert Bates
• Core Java 2: Fundamentals  By Cay S. Horstmann, Gary Cornell

Servlets and JSP

• Head First Servlets and JSP: Passing the Sun Certified Web Component ... By Bryan Basham, Kathy Sierra, Bert 
• Java Servlet & JSP Cookbook  By Bruce W. Perry

Design Patterns

• Head First Design Patterns
• Java Design Patterns: A tutorial  - James W. Cooper

Spring and Hibernate

• Pro Spring 3 by Rob Harrop, Clarence Ho
• Pro Hibernate 3 by Dave Minter, Jeff Linwood
• Spring Persistence With Hibernate by Paul Tepper Fisher, Brian D. Murphy

Struts

• Struts: Kick Start
   by James Turner, Kevin Bedell
• Jakarta Struts Cookbook by Bill Siggelkow
• Programming Jakarta Struts by Chuck Cavaness
• Professional Jakarta Struts by James Goodwill, Richard Hightowe