Most used link:
http://www.w3schools.com/
http://struts.apache.org/api/index.html
Http://e-docs.bea.com/workshop/docs81/doc/en/core/index.html
Http://dev2dev.bea.com.cn/download/school/workshop/WorkshopcnHelp/doc/en/core/index.html
http://dev2dev.bea.com.cn/bbs/index.jspa?categoryId=2
http://www.chedong.com/tech/cvs_card.html
http://java.sun.com/j2ee/sdk_1.3/techdocs/api/index.html
Http://java.sun.com/j2se/1.4.2/docs/api/index.html
Http://java.sun.com/xml/jaxp/dist/1.1/docs/api/
http://junit.sourceforge.net/javadoc/
Http://dev.mysql.com/doc/mysql/en/index.html
http://bsd.huangdongdong.com/strutscn/index.html
Http://java.sun.com/blueprints/corej2eepatterns/patterns/index.html
Http://java.sun.com/developer/onlineTraining/new2java/javamap/intro.html
http://bobcat.webappcabaret.net/javachina/faq/xml_java_01.htm#jaxp_dom_q45
http://java-source.net/
Http://java.sun.com/docs/books/tutorial/index.html
http://www.huihoo.com/