The Jetty project provides an implementation of the Next Protocol Negotiation TLS Extension (NPN) for OpenJDK 7 or greater.
The NPN implementation, although hosted under the umbrella of the Jetty project, is independent of Jetty (the Servlet Container), and can be reused in any other Java network server.
In order to enable NPN support, you need to start the JVM with:
java -Xbootclasspath/p:<path_to_npn_boot_jar> ...
path_to_npn_boot_jar is the path on file system for the NPN Boot jar file, for example http://repo2.maven.org/maven2/org/mortbay/jetty/npn/npn-boot/7.6.2.v20120308/npn-boot-7.6.2.v20120308.jar