第一步:

Gradle offline work 是否打钩了，如果打钩了，取消掉，然后重新gradle一下，应该就正常了

第二步：

   配置  allprojects  ->repositories

maven  {url "https://maven.aliyun.com/repository/jcenter"}
maven { url 'https://maven.aliyun.com/repository/google' }
maven { url 'https://maven.aliyun.com/repository/public' }
maven {url 'https://gitee.com/liuchaoya/libcommon/raw/master/repository/'}
maven { url "https://jitpack.io" }
maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
maven { url "https://dl.bintray.com/umsdk/release" }
maven { url 'https://jitpack.io' }
maven {url  "https://dl.bintray.com/rongcloud/maven"}

第三步：

File->Settings->Build,Execution,Deployment->Compiler的Command-line Options:选项，如果有配置去掉