问题如下：无法解析XXX依赖
1）首先我们先清理一下
2）然后进行编译
3）此时出现如下错误：
Cannot access nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public/) in offline mode and the artifact org.apache.spark:spark-core_2.12:pom:3.0.0 has not been downloaded from it before.
4）找到原因之后我们打开Maven
5）重新打包，发现打包成功
