https://qooah.com/2012/12/07/%e5%a5%bd%e6%b6%88%e6%81%af%ef%bc%81android-%e5%b9%b3%e6%9d%bf%e9%9b%bb%e8%85%a6%e5%b8%82%e5%a0%b4%e4%bd%94%e6%9c%89%e7%8e%87%e9%81%94%e5%88%b0-42-7/