mvn命令格式：
You must specify a valid lifecycle phase
or a goal in the format <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>.
第一种格式：lifecycle phase Available lifecycle phases are: default生命周期 validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, clean生命周期 pre-clean, clean, post-clean, site生命周期 pre-site, site, post-site, site-deploy.
第二种格式：a goal in the format <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>
举例说明：
查看help插件的帮助信息
mvn help:help
查看dependency的详细帮助信息
mvn dependency:help -Ddetail=true
其他说明： -Ddetail=true 显示详细的执行信息 To see the full stack trace of the errors, re-run Maven with the -e switch. Re-run Maven using the -X switch to enable full debug logging. -P 显示的激活一个profile -D 显示的指定系统属性