dex2jar

http://code.google.com/p/dex2jar/

dex2jar contains 4 compment

1. dex-reader is designed to read the Dalvik Executable (.dex/.odex) format. It has a light weight API similar with ASM. An example here
2. 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.
3. dex-ir used by dex-translator, is designed to represent the dex instruction
4. dex-tools tools to work with .class files. here are examples:
   • Modify a apk
   • DeObfuscate a jar