为啥unlock 失败了，有时候又没有报错，好奇怪
https://blog.csdn.net/tklwj/article/details/85161695?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522166789754416782425687243%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request_id=166789754416782425687243&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~baidu_landing_v2~default-1-85161695-null-null.142^v63^control,201^v3^control_2,213^v1^control&utm_term=MediaRecorder%2BCamera&spm=1018.2226.3001.4449
看看这个
