macOS上flutter开发环境搭建填坑过程（Android）

最近想玩下手机APP开发，看到flutter势头不错，因而便装了个开发环境。

个人环境是macOS 10.12.6，装好了xcode以及Android Studio。flutter安装没太多可说的，装完后运行 flutter doctor 查看是否有报错。 解决掉全部问题后，试了在iOS模拟器中运行APP，一切正常。接下来尝试在Android手机上运行APP，噩梦开始了。

无论在Android studio里运行仍是在终端里使用命令 flutter run 运行，均报错

➜  foo flutter run
Launching lib/main.dart on EVA TL00 in debug mode...
Initializing gradle...                                       1.5s
Resolving dependencies...
* Error running Gradle:
ProcessException: Process "/Users/lynx/Android/foo/android/gradlew" exited
abnormally:

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring root project 'android'.
> Could not resolve all artifacts for configuration ':classpath'.
   > Could not resolve com.android.tools.build:gradle:3.2.1.
     Required by:
         project :
      > Could not resolve com.android.tools.build:gradle:3.2.1.
         > Could not get resource
         'https://dl.google.com/dl/android/maven2/com/android/tools/build/gradle
         /3.2.1/gradle-3.2.1.pom'.
            > Could not HEAD
            'https://dl.google.com/dl/android/maven2/com/android/tools/build/gra
            dle/3.2.1/gradle-3.2.1.pom'.
               > dl.google.com:443 failed to respond
      > Could not resolve com.android.tools.build:gradle:3.2.1.
         > Could not get resource
         'https://jcenter.bintray.com/com/android/tools/build/gradle/3.2.1/gradl
         e-3.2.1.pom'.
            > Could not HEAD
            'https://jcenter.bintray.com/com/android/tools/build/gradle/3.2.1/gr
            adle-3.2.1.pom'.
               > jcenter.bintray.com:443 failed to respond

* 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 0s
  Command: /Users/lynx/Android/foo/android/gradlew app:properties


Please review your Gradle project setup in the android/ folder.

开始时候觉得是网络问题，更换各类代理以及源，均无用。

因而在Google上搜，试过各类方法后，在 https://github.com/flutter/flutter/issues/22470 这里看到有人提到须要修改 flutter_app\android\gradle\wrapper\gradle-wrapper.properties 内的gradle版本至4.6（默认为4.10.2） distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-all.zip 改完后继续运行，发现报错找不到Android-27，因而打开sdkmanager安装之，终于解决问题。

心得：国内网络链接到国外真心是大坑；gradle也是巨大的坑。