[Android][AS]Error:Failed to find Build Tools revision 26.0.2

今天手癢，去升級 AS 到3.0.1，然後出現如下錯誤，

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Error:Failed to find Build Tools revision 26.0.2

Consult IDE log for more details (Help | Show Log)

<a href="install.build.tools">Install Build Tools 26.0.2 and sync project</a>

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原因：

Sdk\build-tools目錄下沒有 26.0.2 安裝版本

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嘗試解決方法：

從同事那 copy 一份，放到以下目錄，

C:\Users\xxx\AppData\Local\_Android\Sdk\build-tools\26.0.2

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結果報如下錯誤：

Error:Could not run build action using Gradle distribution 'https://services.gradle.org/distributions/gradle-4.1-all.zip'.

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然後按如下方法改：

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
}
将appcompat-v7:26.1.0' 改为:
appcompat-v7:26.+'
将以下这两行代码删掉.然后同步:
androidTestImplementation 'com.android.support.test:runner:1.0.1'
androidTestImplementation'com.android.support.test.espresso:espresso-core:3.0.1'

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結果報以下錯誤

Error:Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve junit:junit:4.12.
<a href="openFile:D:/Users/champwang/AndroidStudioProjects/My_Application_20171218/app/build.gradle">Open File</a><br><a href="Unable to resolve dependency for &#39;:app@debugUnitTest/compileClasspath&#39;: Could not resolve junit:junit:4.12.">Show Details</a>

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將以下這行刪除，然後就OK了。

    testImplementation 'junit:junit:4.12'

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总结，从一开始按以下改就可以了，改的地方为 app下的  build.gradle 。

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dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
//    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.android.support:appcompat-v7:26.+'

    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
//    testImplementation 'junit:junit:4.12'
//    androidTestImplementation 'com.android.support.test:runner:1.0.1'
//    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
}


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现在还有一个小问题， 每次去 创建新的 activity的 时候， 又會去修改上面這一段。
如果有新建 aty， 還是要手動再改一下。