https://qooah.com/2012/09/04/%e5%a0%b1%e5%91%8a%e7%a8%b1-android-%e5%b8%82%e5%a0%b4%e4%bd%94%e6%9c%89%e7%8e%87%e6%8c%81%e7%ba%8c%e4%b8%8a%e5%8d%87%e4%bd%86%e5%9c%a8%e7%be%8e%e5%9c%8b%e5%8d%bb%e4%b8%8b%e9%99%8d-4-5/