安装Android SDK Platform Tools，总是报校验和错误：
Done loading packages.
Preparing to install archives
Downloading Android SDK Platform-tools, revision 26.0.2
Download interrupted: Connection to https://dl.google.com refused
Done. Nothing was installed.
Preparing to install archives
Downloading Android SDK Platform-tools, revision 26.0.2
Download finished with wrong checksum. Expected 98832431e339c82be1fe910a733a3782071200fd, got 1be4d6d486ff4b8f2edcdf801d27a6ce5c1eba8c.
Done. Nothing was installed.
解决方法：
为了避免在校验和出错，可以自己下载解压安装。
- 下载：SDK Platform-Tools
- 解压到android的SDK的根目录，我的为C:\Users\username\AppData\Local\Android\Sdk
- 新的目录为C:\Users\username\AppData\Local\Android\Sdk\platform-tools
- 运行SDK Manager.exe