Could not resolve all files for configuration ':classpath'.问题解决

今天，使用Android Studio 3.0.1 打开下载的工程项目，build project时结果报错，如下：

Error:A problem occurred configuring root project 'apptest'.
> Could not resolve all files for configuration ':classpath'.
   > Could not resolve com.android.tools.build:gradle:3.0.0.
     Required by:
         project :
      > Could not resolve com.android.tools.build:gradle:3.0.0.
         > Could not get resource 'https://dl.google.com/dl/android/maven2/com/android/tools/build/gradle/3.0.0/gradle-3.0.0.pom'.
            > Could not GET 'https://dl.google.com/dl/android/maven2/com/android/tools/build/gradle/3.0.0/gradle-3.0.0.pom'.
               > sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException:unable to find valid certification path to requested target

解决办法为将com.android.tools.build:gradle的版本号和Android studio的版本号一致。