gradle -- 使用国内阿里云镜像解决下载速度慢的问题

在build.gradle上加入如下url：

buildscript { 
    repositories { 
        maven { url 'https://plugins.gradle.org/m2/' }
        maven { url 'http://maven.aliyun.com/nexus/content/repositories/google' }
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' } 
        maven { url 'http://maven.aliyun.com/nexus/content/repositories/jcenter'} 
}
allprojects { 
        repositories { 
            maven { url 'https://plugins.gradle.org/m2/' } 
            maven { url 'http://maven.aliyun.com/nexus/content/repositories/google' } 
            maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }  
            maven { url 'http://maven.aliyun.com/nexus/content/repositories/jcenter'} 
        } 
}