https://qooah.com/2011/06/27/android-market-%e6%9b%b4%e6%96%b0-%e8%b2%bc%e5%bf%83%e8%bf%bd%e5%8a%a0%e4%bd%bf%e7%94%a8%e8%80%85%e8%a9%95%e7%b5%b1%e8%a8%88/