java怎么把HTML界面做成pdf格式打印

java怎么把HTML界面做成pdf格式打印，遇到难题，求帮助

http://blog.csdn.net/chenaini119/article/details/52038868
谢谢

http://blog.csdn.net/sinat_28505133/article/details/56017309

http://www.open-open.com/doc/view/8d8f3fc183584f7ca52c8a4ed3a0164e

这个是官方文档http://howtodoinjava.com/apache-commons/create-pdf-files-in-java-itext-tutorial/