使用阿里云镜像，解决AS中gradle下载太慢的问题

 在AndroidStudio的build.gradle(Project:projectName)里边添加如下的阿里云镜像仓库地址：

buildscript {
    repositories {
        google()
        jcenter()
        //阿里云镜像仓库地址
        maven{ url 'http://maven.aliyun.com/nexus/content/groups/public/'}
    }
}
 
allprojects {
    repositories {
        google()
        jcenter()
        //阿里云镜像仓库地址
        maven{ url 'http://maven.aliyun.com/nexus/content/groups/public/'}
    }
}