https://qooah.com/2012/09/19/google-%e6%8a%b5%e5%88%b6%e4%bf%ae%e6%94%b9%e7%b3%bb%e7%b5%b1%e6%85%8b%e5%ba%a6%e6%88%96%e4%bb%a4-android-%e9%99%a3%e7%87%9f%e5%88%86%e8%a3%82/