问题描述
我正在使用Maven版本3.5.3，并且在构建项目时，我在WEB-INF中获得了两个版本的 apache commons-lang3 （ v3.1和v3.4 ），即使我在父pom.xml的 依赖性管理中明确指定了v.3.4。
I am using maven version 3.5.3 and while building my project, I am getting two versions of apache commons-lang3 in my WEB-INF (v3.1 and v3.4) even when I have explicitly specified v.3.4 in my "dependency-management" of my parent pom.xml.
两者具有相同的groupId和artifactId。
Both have the same groupId and artifactId.
我很困惑。这是Maven的预期行为吗？在什么情况下会发生这种情况？我的印象是，如果依赖项具有相同的groupId和artifactId，则maven会将所有依赖项解析为一个jar。
I am confused. Is this expected behavior of maven? Under what circumstances does this happen? I was under the impression that maven resolves all dependencies to only one jar if dependencies have same groupId and artifactId.
推荐答案
Maven可以。
对于相同的groupId和相同的artifactId，Maven软件包目标的默认行为是仅打包它们的一个版本。请注意，如果有多个版本可用，则Maven选择的版本实际上是不可预测的。
And Maven does.
For a same groupId and a same artifactId, the default behavior of a Maven package goal is packaging only one version of them. Note that if multiple versions are available, the chosen version by Maven is not really predictable.
我想像一下，您的构建会执行一次将jar手动复制到WEB-INF文件夹（例如，通过Maven插件）或pom（或的父级）指定。
I imagine that at a time your build performs a manual copy from the jar into the WEB-INF folder (via a Maven plugin for example), or your pom (or a parent of) specifies an overlay in the WAR.
mvn依赖项：tree 命令应该可以帮助您了解引用或提取不同版本的位置。
The mvn dependency:tree command should help you to understand where the distinct versions are referenced or pulled.
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