Gradle DSL method not found: 'google()'

报错信息如下：
Gradle DSL method not found: 'google()'
Possible causes:

• The project 'JustTest' may be using a version of the Android Gradle plug-in that does not contain the method (e.g. 'testCompile' was added in 1.1.0).
  Upgrade plugin to version 3.1.2 and sync project
• The project 'JustTest' may be using a version of Gradle that does not contain the method.
  Open Gradle wrapper file
• The build file may be missing a Gradle plugin.
  Apply Gradle plugin

错误原因分析：没找到google(),The google() repo is a shortcut to looks in Google's Maven repository for dependencies. It was introduced with gradle v.4.0。(使用条件)It requires (currently)Gradle v.4、Android Studio 3.x.、Gradle plugin for Android 3.x

解决问题办法：

• 1、将google()替换成maven {url 'https://maven.google.com'}
• 2、满足上面使用google()的三个条件。