Android studio: Could not resolve com.android.tools.build:gradle:3.2.1

Android studio 导入旧项目,  编译时出现：
Could not resolve com.android.tools.build:gradle:3.2.1

原因可能是由于连接仓库 时，网络不太好

修改build.gradle，改成阿里云的仓库，注释Google 官方的仓库

    repositories {
//        mavenLocal()
//        jcenter()
//        maven {
//            url 'https://maven.google.com/'
//            name 'Google'
//        }
//        maven {
//            url 'http://maven.aliyun.com/nexus/content/repositories/releases/'
//        }

        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
    }

所以，关键是

maven { url 'https://maven.aliyun.com/repository/google' }
maven { url 'https://maven.aliyun.com/repository/jcenter' }
maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }