https://qooah.com/2011/06/22/%e7%b6%b2%e8%b7%af%e9%99%b7%e9%98%b1-%e4%bb%bf%e5%a6%82-android-market-%e7%9a%84%e9%87%a3%e9%ad%9a%e7%b6%b2%e7%ab%99/