前面的安装这里就不叙述了。看这里：技术胖的Flutter（http://jspang.com/post/flutte...）
按照步骤安装后，还是一直报错，到绝望。。。
错误代码如下：
Error running Gradle:
ProcessException: Process "D:\project\Flutter\flutter_app\android\gradlew.bat" exited abnormally:
> Configure project :app
Checking the license for package Android SDK Platform 27 in C:\Users\Administrator.WINMICR-H4QQDHF\AppData\Local\Android\Sdk\licenses
Warning: License for package Android SDK Platform 27 not accepted.
FAILURE: Build failed with an exception.
* Where:
Build file 'D:\project\Flutter\flutter_app\android\build.gradle' line: 26
* What went wrong:
A problem occurred evaluating root project 'android'.
> A problem occurred configuring project ':app'.
> Failed to install the following Android SDK packages as some licences have not been accepted.
platforms;android-27 Android SDK Platform 27
To build this project, accept the SDK license agreements and install the missing components using the Android Studio SDK Manager.
Alternatively, to transfer the license agreements from one workstation to another, see http://d.android.com/r/studio-ui/export-licenses.html
Using Android SDK: C:\Users\Administrator.WINMICR-H4QQDHF\AppData\Local\Android\Sdk
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 1s
Command: D:\project\Flutter\flutter_app\android\gradlew.bat app:properties
Finished with error: Please review your Gradle project setup in the android/ folder.
解决办法：
把项目的android/app目录下的build.gradle文件中的sdk版本号改掉，原本是27，改成28.
路径：
代码如下：
