AndroidStudio升级报错Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve c

近日升级AS到3.2.1版本，新建工程时报错：


 

Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve com.android.support:appcompat-v7:28.0.0.
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Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve com.android.support.constraint:constraint-layout:1.1.3.
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Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.test:runner:1.0.2.
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Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.test.espresso:espresso-core:3.0.2.
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Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:28.0.0.
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Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve com.android.support.constraint:constraint-layout:1.1.3.
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Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:28.0.0.
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Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve com.android.support.constraint:constraint-layout:1.1.3.
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Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not resolve junit:junit:4.12.
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错误原因：项目默认配置了gradle 4.6版本，镜像服务器错误（mirrors.neusoft.edu.cn 没有提供下载服务）导致无法下载gradle-4.6-all.zip，无法完成编译。

 

解决方法1：降低gradle版本

• 打开 gradle/wrapper/gradle-wrapper.properties，修改gradle版本为本地已下载版本。如gradle-4.4-all.zip

distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-all.zip

记得同时修改build.gradle内容：3.1.0

dependencies {
    classpath 'com.android.tools.build:gradle:3.2.1'    
}

解决方法2：更新到最新版本

• 不使用镜像地址下载gradle-4.6-all.zip，因为镜像地址连接失败，所以把它拿掉。
  找到/Users/lvxiangan/.gradle文件夹，打开gradle.properties
   

  ## For more details on how to configure your build environment visit
  # http://www.gradle.org/docs/current/userguide/build_environment.html
  #
  # Specifies the JVM arguments used for the daemon process.
  # The setting is particularly useful for tweaking memory settings.
  # Default value: -Xmx1024m -XX:MaxPermSize=256m
  # org.gradle.jvmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8
  #
  # When configured, Gradle will run in incubating parallel mode.
  # This option should only be used with decoupled projects. More details, visit
  # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
  # org.gradle.parallel=true
  #Thu Dec 06 23:52:05 CST 2018
  使用#号注释掉以下4行
  systemProp.http.proxyHost=mirrors.neusoft.edu.cn
  systemProp.http.proxyPort=80
  systemProp.https.proxyHost=mirrors.neusoft.edu.cn
  systemProp.https.proxyPort=80

  或者删除整个文件。重启AS，可以看到正在重新下载gradle-4.6-all.zip
  
   
• 如果上一步下载很慢，可以通过网盘或迅雷下载到本地，从本地直接加载。
  
  下载好复制到 /Users/lvxiangan/.gradle/wrapper/dists/gradle-4.6-all/bcst21l2brirad8k2ben1letg 文件夹下，然后重启AS。
  
  注意：bcst21l2brirad8k2ben1letg 文件夹名称是由系统随机产生，请不要尝试修改它。

最后来一张成功编译图，晚安！