jobo, famous crawler open source which is implemented by java. used in many big websites. You will need a Java Runtime Environment 1.3 or later (on many System Java 1.2 is installed, it will NOT work !).

针对音乐论坛的爬虫程序 给出地址匹配特征，精确爬取用户需要的网页-Music forum for reptiles given address matches the characteristics of the procedure, precise climb pages users need to check

HTML Crawler written in Java code