macOS上flutter開發環境搭建填坑過程（Android）

最近想玩下手機APP開發，看到flutter勢頭不錯，因而便裝了個開發環境。

個人環境是macOS 10.12.6，裝好了xcode以及Android Studio。flutter安裝沒太多可說的，裝完後運行 flutter doctor 查看是否有報錯。 解決掉全部問題後，試了在iOS模擬器中運行APP，一切正常。接下來嘗試在Android手機上運行APP，噩夢開始了。

無論在Android studio裏運行仍是在終端裏使用命令 flutter run 運行，均報錯

➜  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.

開始時候覺得是網絡問題，更換各類代理以及源，均無用。

因而在Google上搜，試過各類方法後，在 https://github.com/flutter/flutter/issues/22470 這裏看到有人提到須要修改 flutter_app\android\gradle\wrapper\gradle-wrapper.properties 內的gradle版本至4.6（默認爲4.10.2） distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-all.zip 改完後繼續運行，發現報錯找不到Android-27，因而打開sdkmanager安裝之，終於解決問題。

心得：國內網絡鏈接到國外真心是大坑；gradle也是巨大的坑。