pom.xml文件中dependency中optional属性的作用

最新推荐文章于 2025-07-07 20:53:31 发布

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#pom #optional

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本文探讨了在Maven项目管理中如何通过设置<optional>true</optional>来控制依赖传递的问题。当一个项目依赖另一个项目时，可以通过将依赖标记为可选，阻止不需要的依赖传递到父项目。

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官方文档的说法是

当project-A 依赖project-B, project-B 依赖project-D时

What if we dont want project D and its dependencies to be added to Project A's classpath because we know some of Project-D's dependencies (maybe Project-E for example) was missing from the repository, and you don't need/want the functionality in Project-B that depends on Project-D anyway. In this case, Project-B's developers could provide a dependency on Project-D that is <optional>true</optional>, like this:

<dependency>
  <groupId>sample.ProjectD</groupId>
  <artifactId>ProjectD</artifactId>
  <version>1.0-SNAPSHOT</version>
  <optional>true</optional>
</dependency>

所以当project-B的<optional>true</optional>时, project-A中如果没有显式的引入project-D, 则project-A不依赖project-D, 即project-A可以自己选择是否依赖project-D

默认<optional>的值为false, 及子项目必须依赖