一个小的音乐播放器的例子，里面有很多有用的代码，可以实现播放，暂停，播放列表，上下一首，随机播放，顺序播放等，还可以最小化到托盘-A small example of the music player, there are many useful code, can achieve playback, pause, play list, on the next song, random playing, sequential playing, can also be minimized to t