All modern browsers can nowadays record audio from user's microphone:

First demo: http://webaudiodemos.appspot.com/AudioRecorder/index.html, inspect the page to see the Javascript source code. The server is set to receive WAV file upload.

Second demo: http://danieldemmel.me/JSSoundRecorder/, source repo: https://github.com/daaain/JSSoundRecorder

Tutorial: http://www.html5rocks.com/en/tutorials/getusermedia/intro/.

I know of no one willing to install Java in their browsers and to do recordings for opensource projects.