問題如下：無法解析XXX依賴
1）首先我們先清理一下
2）然后進行編譯
3）此時出現如下錯誤：
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）找到原因之后我們打開Maven
5）重新打包，發現打包成功
