jcenter下载不了时，用国内镜像下载解决

修改build.gradle,以下是原本的配置信息

buildscript {

    repositories {

        google()

        jcenter()

}

    dependencies {

        classpath 'com.android.tools.build:gradle:3.1.4'

        // NOTE: Do not place your application dependencies here; they belong

// in the individual module build.gradle files

    }

}

allprojects {

    repositories {

        google()

        jcenter()

}

}

task clean(type:Delete) {

    delete rootProject.buildDir

}

修改成以下的配置信息

buildscript{

    repositories{

        maven{ url'http://maven.aliyun.com/nexus/content/groups/public/' }

        maven{ url'http://maven.aliyun.com/nexus/content/repositories/jcenter'}

        google()

}

    dependencies{

        classpath'com.android.tools.build:gradle:3.1.4'

        // NOTE: Do not place your application dependencies here; they belong

// in the individual module build.gradle files

    }

}

allprojects{

    repositories{

        maven{ url'http://maven.aliyun.com/nexus/content/groups/public/' }

        maven{ url'http://maven.aliyun.com/nexus/content/repositories/jcenter'}

}

}

task clean(type: Delete) {

    delete rootProject.buildDir

}