Android Studio Gradle无法获取pom文件

错误提示：

Error:Execution failed for task ':app:lintVitalRelease'.
> Could not resolve all artifacts for configuration ':app:debugAndroidTestRuntimeClasspath'.
   > Could not resolve com.android.support.test:runner:1.0.2.
     Required by:
         project :app
      > Could not resolve com.android.support.test:runner:1.0.2.
         > Could not get resource 'https://dl.google.com/dl/android/maven2/com/android/support/test/runner/1.0.2/runner-1.0.2.pom'.
            > Could not GET 'https://dl.google.com/dl/android/maven2/com/android/support/test/runner/1.0.2/runner-1.0.2.pom'.
               > Connect to dl.google.com:443 [dl.google.com/127.0.0.1] failed: Connection refused: connect
   > Could not resolve com.android.support.test.espresso:espresso-core:3.0.2.
     Required by:
         project :app
      > Could not resolve com.android.support.test.espresso:espresso-core:3.0.2.
         > Could not get resource 'https://dl.google.com/dl/android/maven2/com/android/support/test/espresso/espresso-core/3.0.2/espresso-core-3.0.2.pom'.
            > Could not GET 'https://dl.google.com/dl/android/maven2/com/android/support/test/espresso/espresso-core/3.0.2/espresso-core-3.0.2.pom'.
               > Connect to dl.google.com:443 [dl.google.com/127.0.0.1] failed: Connection refused: connect

 解决方法，在Project的build.gradle里的allprojects里添加：

maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }