问题
I have a spring boot project here: https://github.com/jcasbin/jcasbin-springboot-plugin. I encountered the following error in Travis CI:
shell
3.43s$ ./mvnw install -DskipTests=true -Dmaven.javadoc.skip=true -B -V
/home/travis/build/jcasbin/jcasbin-springboot-plugin
Picked up _JAVA_OPTIONS: -Xmx2048m -Xms512m
Error: Could not find or load main class org.apache.maven.wrapper.MavenWrapperMain
The command "eval ./mvnw install -DskipTests=true -Dmaven.javadoc.skip=true -B -V " failed. Retrying, 2 of 3.
It seems that the mvnw command fails. This file is generated by my IDE: IntelliJ IDEA 2018.1. I don't know what it is used for and why does it fail?
I already fired an issue in Spring Boot's github issues here, but Spring project said it's Maven wrapper's issue and pointed me here. I don't quite understand what it means. Is it a Maven bug? How to fix the error then?
回答1:
You're missing the .mvn folder in your git repository. You should have a folder called .mvn which contains the files wrapper/maven-wrapper.jar, wrapper/maven-wrapper.properties and jvm.config. Perhaps you missed it because it's a hidden folder.
Try doing git add -f .mvn from the command line then commit and push.
回答2:
Phil's answer is correct.
And here is how to create .mvn directory with needed jar inside.
I found the answer here
(https://www.baeldung.com/maven-wrapper)
If you have maven and you want to make maven wrapper working, you need to setup maven wrapper:
mvn -N io.takari:maven:wrapper
It should create .mvn directory and put needed jar in it.
回答3:
i actually did just mvn clean install and it worked, i am actually using older version of spring 2.0 to be specific
来源：https://stackoverflow.com/questions/50104172/could-not-find-or-load-main-class-org-apache-maven-wrapper-mavenwrappermain