https://qooah.com/2012/02/01/%e8%aa%bf%e6%9f%a5%e6%8c%87-android-%e7%94%a8%e5%ae%b6%e6%9b%b4%e5%ae%b9%e6%98%93%e5%9c%a8%e7%ac%ac%e4%b8%80%e6%ac%a1%e7%b4%84%e6%9c%83%e7%9a%84%e6%99%82%e5%80%99%e5%b0%b1%e4%b8%8a%e5%ba%8a/