增加单例模式，打开文件时会调用同一个进程，增加拖入事件使得可以通过拖入文件来进行播放。#63
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ljzloser wants to merge 2 commits intoeee555:masterfrom
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增加单例模式，打开文件时会调用同一个进程，增加拖入事件使得可以通过拖入文件来进行播放。#63ljzloser wants to merge 2 commits intoeee555:masterfrom
ljzloser wants to merge 2 commits intoeee555:masterfrom
