https://qooah.com/2012/04/08/google-android-%e7%b3%bb%e7%b5%b1%e5%9c%a8%e7%be%8e%e5%9c%8b%e6%88%90%e7%82%ba%e5%a4%a7%e5%93%a5%e5%a4%a7-%e5%b8%82%e5%a0%b4%e4%bd%94%e6%9c%89%e9%a1%8d%e9%81%94-50-%e4%bb%a5%e4%b8%8a/