在所有上传工件后，maven 是否总是部署 maven-metadata.xml 文件

Question

maven 部署工件有什么顺序吗？据我所知，我可以说它上传了所有工件，最后它更新了 maven-medata.xml 文件

http://localhost:8000/mavenrepository/test1/com/mypackage/mavenproject1/1.0-SNAPSHOT/maven-metadata.xml http://localhost:8000/mavenrepository/test1/com/mypackage/mavenproject1/maven-metadata.xml

现在是否保证maven在上传其他工件后总是最后上传这2个文件？

Answer 1

Maven 总是以相同的顺序部署工件文件。它通常看起来像这样：

[INFO] --- maven-deploy-plugin:2.7:deploy (default-deploy) @ hello-world ---
Downloading: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/1.0-SNAPSHOT/maven-metadata.xml
Uploading: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/1.0-SNAPSHOT/hello-world-1.0-20160430.031713-1.jar
Uploaded: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/1.0-SNAPSHOT/hello-world-1.0-20160430.031713-1.jar (3 KB at 11.5 KB/sec)
Uploading: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/1.0-SNAPSHOT/hello-world-1.0-20160430.031713-1.pom
Uploaded: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/1.0-SNAPSHOT/hello-world-1.0-20160430.031713-1.pom (2 KB at 41.6 KB/sec)
Downloading: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/maven-metadata.xml
Uploading: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/1.0-SNAPSHOT/maven-metadata.xml
Uploaded: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/1.0-SNAPSHOT/maven-metadata.xml (798 B at 21.1 KB/sec)
Uploading: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/maven-metadata.xml
Uploaded: http://localhost:48080/storages/storage0/snapshots/org/foo/examples/hello-world/maven-metadata.xml (312 B at 8.7 KB/sec)
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------

如您所见，它所做的第一件事是尝试在工件级别解析maven-metadata.xml 文件，以确定该工件是否有其他版本以及是否生成全新的maven-metadata.xml 文件，或使用它正在部署的新版本更新现有版本（如果有的话）。 maven-metadata.xml 文件始终在部署结束时生成或更新。

maven-metadata.xml 文件可以位于三个级别：

• 工件级别：这是在groupId/artifactId 级别，（例如，如果您的groupId 是org.foo.examples 并且您的artifactId 是hello-world，则路径将为org/foo/examples/hello-world/maven-metadata.xml）。这用于管理基本版本或发布版本。
• 版本级别：这在groupId/artifactId/version 级别，（例如，如果您的groupId 是org.foo.examples 并且您的artifactId 是hello-world 并且版本是1.0-SNAPSHOT ，路径将是org/foo/examples/hello-world/1.0-SNAPSHOT/maven-metadata.xml)。这用于管理带时间戳的快照。
• 插件组级别：在插件的groupId级别，用于管理同一插件组下的不同插件。

有关 Maven 元数据如何工作的详细说明，请查看我整理的 this article。