(Recently, the project needs, so I studied offline video and audio playback. I referred to the source code written by two predecessors, and on this basis, I realized online video playback. At the same time, the background breakpoint cache, and automatically switch to local video playback after the cache ends, which can ensure fluency, and also beautify the playback button and progress bar! After downloading, it is absolutely available, and there is no regret. Of course, it is necessary for video resources to support http streaming!)