dex2jar https://code.google.com/p/dex2jar/
http://blog.csdn.net/kesenhoo/article/details/6544094
dex2jar contains following compment
dex-reader is designed to read the Dalvik Executable (.dex/.odex) format. It has a light weight API similar with ASM. An example here dex-translator is designed to do the convert job. It reads the dex instruction to dex-ir format, after some optimize, convert to ASM format. dex-ir used by dex-translator, is designed to represent the dex instruction dex-tools tools to work with .class files.