https://qooah.com/2011/02/26/%e7%94%a8%e6%88%b6%e5%8f%8d%e6%98%a0nexus-s-%e5%8d%87%e7%b4%9aandroid-2-3-3%e5%be%8c%e5%b1%8f%e5%b9%95%e8%ae%8a%e8%89%b2/