java

http://docs.oracle.com/javase/6/docs/api/

JavaTM Platform Enterprise Edition, v 5.0
http://java.sun.com/javaee/5/docs/api/

1.Hibernate API Documentation (3.2.2.ga)

http://www.hibernate.org/hib_docs/v3/api/

2.Spring Framework API 2.5

http://static.springframework.org/spring/docs/2.5.x/api/index.html

3.Struts 1.3.8 API

http://struts.apache.org/1.3.8/apidocs/index.html

4.Struts 2 Core 2.0.11.1 API

http://struts.apache.org/2.0.11.1/struts2-core/apidocs/index.html

5.ajax4jsf:JSF的Ajax框架

http://www.jboss.org/file-access/default/members/jbossrichfaces/freezone/docs/apidoc_framework/index.html

6.JBoss API

http://docs.jboss.org/jbossas/javadoc/4.0.5/

7.OSGI R4

http://docs.huihoo.com/javadoc/osgi/r4/

8.JBoss Seam

http://docs.jboss.com/seam/2.1.0.A1/api/

9.Seam JSF Controls 2.1.0.A1 API

http://docs.jboss.com/seam/2.1.0.A1/ui/apidocs/

10.ROR

http://docs.huihoo.com/api/ruby-on-rails/

11.Ruby1.8.4

http://docs.huihoo.com/api/ruby/core/1.8.4/

12.Ruby Stdlib

http://docs.huihoo.com/api/ruby/stdlib/0.10.1/

13.JBPM/BPEL1.1

http://docs.jboss.com/jbpm/bpel/v1.1/javadoc/

14.Groovy JDK API Specification

This document describes the methods added to the JDK to make it more groovy.

http://groovy.codehaus.org/groovy-jdk/

15.Groovy (1.6-beta-1) API

http://groovy.codehaus.org/api/index.html

16.Groovy 1.5 API

http://groovy.codehaus.org/gapi/

17.Grails1.0 API

http://grails.org/doc/1.0.x/api/

18.在线JDK6 API:

http://gceclub.sun.com.cn/Java_Docs/jdk6/html/zh_CN/api/index.html

下载地址:

http://java.sun.com/javase/downloads/index.jsp

19.其他Java SE APIs & Documentation:
[url]
http://java.sun.com/javase/reference/api.jsp[/url]

20.在线Java API List:

http://java.sun.com/reference/api

21.JavaEE5 API(含JSF API)

http://java.sun.com/javaee/5/docs/api/

22.Ajax框架DWR API Doc

http://www.ajaxjs.com/docs/docs/

23.Google Maps API 2.0 参考文档

http://www.step1.cn/GoogleApi/map2/reference.htm