No, App Inventor does not generate Java source code
https://appinventortojava.appspot.com/
https://code.google.com/p/appinventor-java-translation/
If you want to make the leap to Java, I recommend this appinventor java bridge:
https://code.google.com/p/alternate-java-bridge-library/
You will need to re-program your app from scratch however.