https://qooah.com/2012/10/03/google-%e5%85%ac%e4%bd%88%e4%ba%86%e6%9c%80%e6%96%b0-android-%e7%b3%bb%e7%b5%b1%e7%9a%84%e5%88%86%e4%bd%88%e5%9c%96%ef%bc%8cgingerbread-%e4%bb%8d%e7%84%b6%e4%ba%ba%e6%b0%a3%e9%ab%98%e4%bc%81%ef%bc%81/