flutter運行失敗

被牆了導致無法運行項目，報錯如下：

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':flutter_custom_dialog:javaPreCompileDebug'.
> Could not resolve all files for configuration ':flutter_custom_dialog:debugCompileClasspath'.
   > Could not download flutter_embedding_debug.jar (io.flutter:flutter_embedding_debug:1.0.0-540786dd51f112885a89792d678296b95e6622e5)
      > Could not get resource 'https://storage.googleapis.com/download.flutter.io/io/flutter/flutter_embedding_debug/1.0.0-540786dd51f112885a89792d678296b95e6622e5/flutter_embedding_debug-1.0.0-540786dd51f112885a89792d678296b95e6622e5.jar'.
         > Could not GET 'https://storage.googleapis.com/download.flutter.io/io/flutter/flutter_embedding_debug/1.0.0-540786dd51f112885a89792d678296b95e6622e5/flutter_embedding_debug-1.0.0-540786dd51f112885a89792d678296b95e6622e5.jar'.
            > Connect to storage.googleapis.com:443 [storage.googleapis.com/172.217.160.112] failed: Connection timed out: connect

* Try:

我的解決方法：

1.將Android目錄下的build.gradle中的allprojects中添加一句

 .........

allprojects {
    repositories {
        google()
        jcenter()
        maven {url 'https://dl.bintray.com/jetbrains/anko'}

    }
}

...........

2.將fluttersdk安裝目錄下的flutter.gradle也加上這個

位置：\packages\flutter_tools\gradle\flutter.gradle

buildscript {
    repositories {
        google()
        jcenter()
        maven {url 'https://dl.bintray.com/jetbrains/anko'}

    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.0'
    }
}