用JAVA实现GBN（go back N）协议。UDP滑动窗口协议是建立在UDP上的应用层协议之上的。传输层使用的仍是UDP,但在应用层使用滑动窗口技术,并通过模拟TCP的一些机制以保证UDP的低协议处理开销和获得高通信可靠性。-JAVA implementation by GBN (go back N) protocol. UDP sliding window protocol is based on UDP protocol on the application layer above. Transport layer is still using UDP, but in the application layer using a sliding window, and some of the mechanisms by simulating TCP UDP to ensure that the low protocol processing overhead and achieve high communication reliability.