Maven依赖解析（冲突） [英] Maven dependency resolution (conflicted)

问题描述

假设我有四个项目：

• 项目A（依赖于B和D）


• 项目B（依赖于D）


• 项目C（依赖于D）


• 项目D

• Project A (has a dependency on B and D)
• Project B (has a dependency on D)
• Project C (has a dependency on D)
• Project D

在这种情况下，如果我运行项目A，Maven将正确解析对D的依赖。如果我理解正确，Maven总是采用最短的依赖路径。由于D是A的直接依赖，因此将使用它，而不是在B中指定的D。

In this scenario if I run project A, Maven will correctly resolve the dependency to D. If I understand this correctly Maven always takes the dependency with the shortest path. Since D is a direct dependency of A it will be used rather then, the D which is specified within B.

但现在假设这个结构：

• 项目A（依赖于B和C）


• 项目B（依赖于D）


• 项目C（依赖于D）


• 项目D

• Project A (has a dependency on B and C)
• Project B (has a dependency on D)
• Project C (has a dependency on D)
• Project D

在这种情况下，解析D的路径具有相同的深度。发生的事情是Maven会发生冲突。我知道有可能告诉Maven他应该排除依赖关系。但我的问题是如何解决这类问题。我的意思是在现实世界的应用程序中，你有很多依赖性，也可能有很多冲突。

In this case the paths to resolving D have the same depth. What happens is that Maven will have a conflict. I know that it is possible to tell Maven that he should exclude dependencies. But my question is how to adress such kind of problems. I mean in a real world application you have a lot of depenendcies and possibly a lot of conflicts as well.

最佳实践解决方案是真的排除东西还是其他的可能的解决方案吗？当我突然得到ClassNotFound Exception时，我发现很难处理，因为某些版本已经改变，这导致Maven采取不同的依赖关系。知道这一事实的原因使得更容易猜测问题是依赖性冲突。

Is the best practice solution really to exclude stuff or are there other possible solutions to this? I find it very hard to deal with when i suddenly get a ClassNotFound Exception because some versions have changed, which caused Maven to take a differend dependency. Of cause knowing this fact makes it a little bit easier to guess that the problem is a dependency conflict.

我正在使用maven 2.1-SNAPSHOT。

I'm using maven 2.1-SNAPSHOT.

推荐答案

解决此类情况的主要方法是包含< dependencyManagement> 部分在项目的根pom中，您可以在其中指定将使用哪个库的版本。

The maven way of resolving situations like this is to include a <dependencyManagement> section in your project's root pom, where you specify which version of which library will be used.

编辑：

<dependencyManagement>
  <dependencies>
    <dependency>
        <groupId>foo</groupId>
        <artifactId>bar</artifactId>
        <version>1.2.3</version>
    </dependency>
   </dependencies>
</dependencyManagement>

现在无论哪个版本的库foo：bar都是依赖项请求，版本1.2.3将始终用于此项目和所有子项目。

Now no matter which version of library foo:bar is requested by a dependency, version 1.2.3 will always be used for this project and all sub-projects.

参考：

• 依赖管理

• Dependency Management

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