maven

Apache Maven is a software project management and comprehension tool. Based on the concept of a project object model (POM), Maven can manage a project's build, reporting and documentation from a central piece of information.

Apache Maven是一个软件项目管理和理解工具。
基于项目对象模型（POM）的概念，Maven可以从一个中心信息管理项目的构建，报告和文档。

src
    main
        package
    test
        package
    resource

4.0.0
com.imooc.spark
sql-spark2.1.0
1.0

mvn compile 
mvn test
# 删除target
mvn clean
mvn package