//jcenter():用下面一句代替，可以面向加快jar包下载速度
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
        //greendao需要下面一句
        mavenCentral()
        //GreenDaoUpgradeHelper需要下面一句
        maven { url "https://jitpack.io" }