解決方法1：修改build.gradle,註釋掉jcenter()，google()。使用阿里的映象。原因是jcenter google庫無法訪問到導致的問題。雖然我有萬能的爬牆工具，開啟全域性代理依然被我們偉大的發改委牆掉了！

buildscript {
    repositories {
        //google()
        //jcenter()
        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' }
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
    }
}

allprojects {
    repositories {
        //google()
        //jcenter()
        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' }
    }
}