Unknown host 'maven.google.com'

这个问题没有能直接解决…

解决方案：

app/build.gradle 原代码:

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        maven {
            url 'https://maven.google.com/'
            name 'Google'
        }
    }

    dependencies {
        ...
    }
}
allprojects {

    repositories {
        maven {
            url 'https://maven.google.com/'
            name 'Google'
        }
    }
}

第一步：更改 url

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        maven {
            url 'https://dl.google.com/dl/android/maven2'
            name 'Google'
        }
    }

    dependencies {
        ...
    }
}
allprojects {

    repositories {
        maven {
            url 'https://dl.google.com/dl/android/maven2'
            name 'Google'
        }
    }
}

第二部，更改 hosts 文件 （Ubuntu 系统文件路径：/etc/hosts）
sudo gedit /etc/hosts
写入：203.208.40.36 　　　　dl.google.com
写入后的 hosts 文件：

重新编译，搞定!!!
附上参考博客：AndroidStudio编译时Unknown host ‘dl.google.com’. You may need to adjust the proxy settings