问题错误
解压maven后验证是否安装成功，在cmd命令行输入mvn -V报错如下：
No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format : or :[:]:. Available lifecycle phases are: pre-clean, clean, post-clean, 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, pre-site, site, post-site, site-deploy
问题解决
在解压maven的目录下找到，这个文件。
D:\JAVA\apache-maven-3.9.0\lib\maven-model-builder-3.9.0.jar
这个文件我是用7-zip打开的，打开后，一层层文件夹下找到，pom-4.0.0.xml这个文件
打开这个文件，在里面修改一下配置，添加上这句话
<defaultGoal>compile</defaultGoal>
记得再打开看看是不是真的保存上了
成功
