android studio gradle更新一直卡死问题解决

打开工程下build.gradle并按照下图修改保存，然后同步可解 

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        maven{ url 'http://maven.aliyun.com/nexus/content/groups/public/' }
        jcenter()
        google()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:4.2.1'
    }
}

allprojects {
    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' }
        google()
        jcenter()
    }
}