Android Studio 环境问题

问题1：android studio在4.4或4.2手机系统出现java.lang.ClassNotFoundException

defaultConfig {
   multiDexEnabled true
}

depenencies {
   implementation 'com.android.support:multidex:1.0.3'
}
// AndroidManifest.xml 中的application要实现MultiDexApplication这个类
<application
android:name="android.support.multidex.MultiDexApplication"
>
</application

问题2：build.gradle从仓库下载资源失败问题，可从aliyun下载

repositories {
    maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
    maven { url 'http://maven.aliyun.com/nexus/content/repositories/jcenter' }
    maven { url 'http://maven.aliyun.com/nexus/content/repositories/google' }
    maven { url 'http://maven.aliyun.com/nexus/content/repositories/gradle-plugin' }
}

build.gradle相关
待补充。。。