//list files in jar
jar tf xx.jar
//update file in jar
jar uvf xx.jar newfile
jar uvf xx.jar org.google.newclassfile // newclassfile in ./org/google/
//extract jar
jar xf xx.jar
References
http://blog.163.com/yde1208@126/blog/static/958727092012101311253447/
http://nicegege.iteye.com/blog/1181072
http://blog.csdn.net/zhang_red/article/details/17142263