Question

我找不到documentation，Maven在这里说过如何订购已声明的存储库。

考虑以下位置可以配置Maven存储库：

settings.xml在settings/profiles/profile/repositories下
- id：settings-repo1
- id：settings-repo2
settings.xml在settings/mirrors下
- id：settings-mirror1
- id：settings-mirror2

pom.xml

父级project/repositories
- id：pom-parent-repo1
- id：pom-parent-repo2

pom.xml

子project/repositories
- id：pom-child-repo1
- id：pom-child-repo2
子pom.xml的依赖项还使用存储库：
- id：dependency-repo1
- id：dependency-repo2

Maven尝试从所有这些存储库中下载依赖项的顺序是什么？

mvn dependency:list-repositories命令向我显示了一个非常无序的列表，很难相信这是真正的优先级顺序。

Answer 1

我执行了以下操作来确定Maven考虑存储库顺序的顺序：

我将所有XML文件中所有存储库/镜像设置的URL更新为无效的Maven仓库，以强制Maven失败
我跑了mvn compile

以下结果假设某个依赖项从未在本地缓存~/.m2/repository中下载/注册（即，它没有被缓存或以前没有使用其他存储库失败过）。如果您在本地缓存中具有某个依赖项的条目，则Maven将重用该缓存的条目（这还将保存初始的源存储库）以尝试再次获取它。

这是在未配置任何镜像时Maven尝试的操作：

Downloading from settings-repo1: http://settings-repo1.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from settings-repo2: http://settings-repo2.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from pom-child-repo1: http://child-repo1.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from pom-child-repo2: http://child-repo2.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from pom-parent-repo1: http://parent-repo1.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from pom-parent-repo2: http://parent-repo2.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from central: https://repo.maven.apache.org/maven2/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom

并且在配置了镜像时：

Downloading from settings-repo1: http://settings-repo1.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from settings-repo2: http://settings2.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from settings-mirror1: http://settings-mirror1.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from settings-mirror2: http://settings-mirror2.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from pom-parent-repo1: http://parent-repo1.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from pom-parent-repo2: http://parent-repo2.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from central: https://repo.maven.apache.org/maven2/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom

因此订单必须为：

settings.xml
当前项目的pom.xml
父项目的pom.xml

如果已配置任何镜像，它们将仅替换mirrorOf元素标识的原始列表中的相应存储库。如果mirrorOf表达式标识多个存储库，则仅尝试第一个匹配项（按Maven原始顺序（未配置镜像））。例如，如果为settings-mirror1配置了一个镜像（例如<mirrorOf>pom-parent-repo2,pom-child-repo1</mirrorOf>），则存储库搜索顺序将为：

Downloading from settings-repo1: http://settings-repo1.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from settings-repo2: http://settings-repo2.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from settings-mirror1: http://settings-mirror1.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from pom-child-repo2: http://child-repo2.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from pom-parent-repo1: http://parent-repo1.org/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom
Downloading from central: https://repo.maven.apache.org/maven2/org/apache/httpcomponents/httpclient1/4.5.6/httpclient1-4.5.6.pom

至于在依赖项POM文件中声明的存储库，我认为人们不应该在意它们。如果您具有依赖项，则需要在已声明的存储库之一（设置，父pom，pom）中使用此依赖项，否则构建将失败（即使您先前已将另一个项目下载并缓存了该依赖项（无论是否具有子依赖项））。

Maven尝试下载插件时会考虑哪些存储库顺序？

1 个答案: