Flutter启动安卓模拟器报错

PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

配置安卓环境变量：

打开 Android Studio，选择 Confiure -> 'SDK Manager'：

vim ~/.bash_profile

export ANDROID_HOME=/Users/XXX/Library/Android/sdk
export PATH=$PATH:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools

source ~/.bash_profile

此错误，也可能是因为别的方式解决的，在莫名其妙的情况下好的……

新错误：

* What went wrong:
Execution failed for task ':app:desugarDebugFileDependencies'.
> Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
   > Could not download flutter_embedding_debug.jar (io.flutter:flutter_embedding_debug:1.0.0-6bc433c6b6b5b98dcf4cc11aff31cdee90849f32)
      > Could not get resource 'https://storage.googleapis.com/download.flutter.io/io/flutter/flutter_embedding_debug/1.0.0-6bc433c6b6b5b98dcf4cc11aff31cdee90849f32/flutter_embedding_debug-1.0.0-6bc433c6b6b5b98dcf4cc11aff31cdee90849f32.jar'.
         > Could not GET 'https://storage.googleapis.com/download.flutter.io/io/flutter/flutter_embedding_debug/1.0.0-6bc433c6b6b5b98dcf4cc11aff31cdee90849f32/flutter_embedding_debug-1.0.0-6bc433c6b6b5b98dcf4cc11aff31cdee90849f32.jar'.
            > Connect to storage.googleapis.com:443 [storage.googleapis.com/216.58.200.240] failed: connect timed out

解决：找到android->build.gradle，buildscript repositories 的 google()改为maven { url "https://dl.google.com/dl/android/maven2/" }

buildscript {
    ext.kotlin_version = '1.3.50'
    repositories {
        // google()
        maven { url "https://dl.google.com/dl/android/maven2/" }
        jcenter()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

重新运行即可。

原因：
应该是gradle初始化，下载文件的时候卡住了。
解决方法：
更换下载方式和路径。
附注：
此时就算改回google()，也可运行，因为依赖文件已经下载下来了。

参考资料：

flutter 项目报错：Could not resolve all files for configuration ':classpath'
解决flutter：unable to find valid certification path to requested target 的问题

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