http://stackoverflow.com/questions/32587045/visual-studio-2015-installation-hangs-at-android-sdk-setup-api-level-19-and-21
Visual Studio 2015 Installation hangs at Android SDK Setup (API Level 19 and 21) And Level 22
I found a couple post that kept saying to stop the SecondaryInstaller.exe. That stops the installation of the Android SDK altogether. What I found that worked and the SDK installed correctly was stopping the Java.exe process. Everything installed correctly after that process was stopped.在任务管理器里结束SecondaryInstaller.exe进程。会有如下界面，不知道有没有影响。
Android SDK 设置(API 级别 19 和 21)
