Could not get resource ‘https://dl.google.com/dl/android/maven2/com/android/

Gradle sync failed: Connection timed out: connect. If you are behind an HTTP proxy, please configure the proxy settings either in IDE or Gradle.
    Consult IDE log for more details (Help | Show Log) (52 m 5 s 412 ms)

allprojects {
    repositories {
        google()
        //maven { url 'http://raw.github.com/saki4510t/libcommon/master/repository/' }
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
        jcenter()
    }
}