Android ApiDemos示例解析

说明：  如何使用MediaPlayer类来播放声音或是视频。涉及的Activity有三个： MediaPlayerDemo：主Activity，显示示例列表。 MediaPlayerDemo_Audio： 子Activity，用于播放声音，在Launcher中没有图标。 MediaPlayerDemo_Video： 子Activity，用于播放视频，在Launcher中没有图标。 其中MediaPlayerDemo 使用四个按钮用于显示例子列表： 点击按钮后，触发子Activity，比如”Play video from local file” 将启动MediaPlayerDemo_Audio
(How to use the MediaPlayer class to play the sound or the video. There are three Activity involved: MediaPlayerDemo: Master Activity, showing a list of examples. MediaPlayerDemo_Audio: child Activity, used for playing sound, and there is no icon in Launcher. MediaPlayerDemo_Video: child Activity, used to play video, and there is no icon in Launcher. In which MediaPlayerDemo uses four buttons to display the list of examples: Click the button, trigger Activity, such as "Play video from local file" will start MediaPlayerDemo_Audio)