Unable to resolve dependency for ':app@debugUnitTest/compileClasspath':....

新换的mac，各方面配置好后，打开老项目也没问题，建项目时出现如下报错，总感觉是系统各方面没配置好的问题，总是小题大作。。。

我打开翻下墙。重新Rebuild一下就OK了 

Error:Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0. Open File

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Error:Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.test:runner:1.0.1. Open File
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Error:Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.test.espresso:espresso-core:3.0.1. Open File
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Error:Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0. Open File
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Error:Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0. Open File
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Error:Unable to resolve dependency for ':app@release/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0. Open File
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Error:Unable to resolve dependency for ':app@releaseUnitTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0. Open File
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点击详情查看：

1. Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0.

Could not resolve com.android.support.test:runner:1.0.1.

Required by:
    project :app
 > Could not resolve com.android.support.test:runner:1.0.1.
    > Could not get resource 'https://dl.google.com/dl/android/maven2/com/android/support/test/runner/1.0.1/runner-1.0.1.pom'.
          > Could not GET 'https://dl.google.com/dl/android/maven2/com/android/support/test/runner/1.0.1/runner-1.0.1.pom'.
                   > Connect to 127.0.0.1:50176 [/127.0.0.1] failed: Connection refused (Connection refused)
                               > Connection refused (Connection refused)