循环依赖项目的 Eclipse m2e 插件问题答案

【问题标题】：Eclipse m2e plugin issue for cyclic dependent projects循环依赖项目的 Eclipse m2e 插件问题
【发布时间】：2020-09-09 18:18:03
【问题描述】：

我对循环依赖项目的 m2e 插件有疑问。

首先，我知道循环依赖是不好的，maven也不允许，应该避免它们等等。但是我们的遗留项目在没有改变项目结构的情况下被maven化了（循环依赖被继续）。

以前，将每个项目添加到其他项目构建路径并将循环依赖构建路径问题设置为警告是解决方法。这样，我可以在一个项目中进行更改并立即看到另一个项目的效果。

现在项目已经成熟，我想通过启用 m2e 工作区解析（通过选中“从工作区项目解决依赖关系”选项）来实现相同的工作区环境。

在 m2e 版本 1.7.0.20160603-1933 的 eclipse neon（版本：Neon.3 Release (4.6.3) Build id：20170314-1500）中，这是可能的。对应的maven依赖是从workspace项目中解析出来的，虽然build path有循环。

但是，在 eclipse 2019-09 R（版本：2019-09 R (4.13.0) Build id：20190917-1200，m2e 版本为 1.13.0.20190716-1624）及更高版本中，构建会导致无限循环。对于两个循环项目 MY PROJECT A 和 MY PROJECT B，maven 工件 ID 分别为 MYPROJECTAARTIFACTID 和 MYPROJECTBARTIFACTID，下面是 2019-09 R 版本无限构建的 m2e 日志（我无法从 neon 版本收集日志）。

重复一遍，我知道 maven 本身不允许循环项目设置，但一般来说，即使对于具有 maven 特性的项目，eclipse 也允许它。

如何在最新的 Eclipse 版本中实现同样的效果？

2020-05-22 21:19:26,588 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.builder.MavenBuilder - Building project MY PROJECT B
2020-05-22 21:19:26,683 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.DefaultLocalRepositoryProvider - Using manager EnhancedLocalRepositoryManager with priority 10.0 for D:\MAVEN_REPONEW
2020-05-22 21:19:26,697 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.p.r.ProjectRegistryManager - Refreshing: [L/MY PROJECT B/pom.xml]
2020-05-22 21:19:26,709 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.DefaultLocalRepositoryProvider - Using manager EnhancedLocalRepositoryManager with priority 10.0 for D:\MAVEN_REPONEW
2020-05-22 21:19:26,712 [Worker-7: Building Workspace] DEBUG o.e.m.c.internal.embedder.MavenImpl - Reading 1 Maven project(s): [D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml]
2020-05-22 21:19:26,764 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.DefaultUpdatePolicyAnalyzer - Skipped remote request for ...
2020-05-22 21:19:26,868 [Worker-7: Building Workspace] DEBUG o.e.m.c.internal.embedder.MavenImpl - Read 1 Maven project(s) in 156 ms
2020-05-22 21:19:27,036 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.m.MavenMarkerManager - Created marker 'GroupId is duplicate of parent groupId' on resource '/MY PROJECT B/pom.xml'.
2020-05-22 21:19:27,043 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.DefaultLocalRepositoryProvider - Using manager EnhancedLocalRepositoryManager with priority 10.0 for D:\MAVEN_REPONEW
2020-05-22 21:19:27,086 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory - Loading lifecycle mapping for MavenProject: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT @ D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml.
2020-05-22 21:19:27,670 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.c.DefaultDependencyCollector - Dependency collection stats: {ConflictMarker.analyzeTime=637200, ConflictMarker.markTime=709300, ConflictMarker.nodeCount=118, ConflictIdSorter.graphTime=487300, ConflictIdSorter.topsortTime=290200, ConflictIdSorter.conflictIdCount=45, ConflictIdSorter.conflictIdCycleCount=0, ConflictResolver.totalTime=3881500, ConflictResolver.conflictItemCount=72, DefaultDependencyCollector.collectTime=398895400, DefaultDependencyCollector.transformTime=7801200}
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] INFO  o.e.m.c.i.l.LifecycleMappingFactory - Using org.eclipse.m2e.jdt.JarLifecycleMapping lifecycle mapping for MavenProject: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT @ D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml.
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory - Loaded lifecycle mapping in 699 ms for MavenProject: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT @ D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml.
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory - MY PROJECT B is configured by :
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.eclipse.m2e.jdt.javaConfigurator
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.maven.ide.eclipse.configuration.wtp.java.unsupportedDependencyTypeConfigurator
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.eclipse.m2e.wtp.jpa.configurator.jdt
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.maven.ide.eclipse.configuration.wtp.utility.configurator
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.maven.ide.eclipse.configuration.wtp.webfragment.configurator
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.sonatype.m2e.mavenarchiver.jararchiverconfigurator
2020-05-22 21:19:27,785 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.eclipse.m2e.wtp.jaxrs.configurator
2020-05-22 21:19:27,786 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.p.r.DefaultMavenDependencyResolver - Resolving dependencies for P/MY PROJECT B: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT
2020-05-22 21:19:27,786 [Worker-7: Building Workspace] DEBUG o.e.m.c.internal.embedder.MavenImpl - Reading Maven project: D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml
2020-05-22 21:19:27,790 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.DefaultUpdatePolicyAnalyzer - Skipped remote request for com.my.company:... locally cached metadata up-to-date.
2020-05-22 21:19:28,529 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.c.DefaultDependencyCollector - Dependency collection stats: {ConflictMarker.analyzeTime=925200, ConflictMarker.markTime=269600, ConflictMarker.nodeCount=328, ConflictIdSorter.graphTime=1694200, ConflictIdSorter.topsortTime=470600, ConflictIdSorter.conflictIdCount=88, ConflictIdSorter.conflictIdCycleCount=48, ConflictResolver.totalTime=7407900, ConflictResolver.conflictItemCount=309, DefaultDependencyCollector.collectTime=730670400, DefaultDependencyCollector.transformTime=10784800}
2020-05-22 21:19:28,539 [Worker-7: Building Workspace] INFO  o.e.m.c.i.p.WorkspaceClassifierResolverManager - Resolving P/MY PROJECT A: com.my.company:MYPROJECTAARTIFACTID:1.0.1-SNAPSHOT with classifier  to /MY PROJECT A/target/classes
2020-05-22 21:19:28,598 [Worker-7: Building Workspace] DEBUG o.e.m.c.internal.embedder.MavenImpl - Read Maven project: D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml in 812 ms
2020-05-22 21:19:28,598 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.p.r.DefaultMavenDependencyResolver - Resolved dependencies for P/MY PROJECT B: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT in 812 ms
2020-05-22 21:19:28,600 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.DefaultLocalRepositoryProvider - Using manager EnhancedLocalRepositoryManager with priority 10.0 for D:\MAVEN_REPONEW
2020-05-22 21:19:28,601 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory - Loading lifecycle mapping for MavenProject: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT @ D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml.
2020-05-22 21:19:28,607 [Worker-1: Decoration Calculation] DEBUG o.e.j.i.storage.file.FileSnapshot - file=C:\Program Files\Git\etc\gitconfig, isRacyClean=false, read=2020-05-22 21:18:57.612000000, lastModified=2020-04-28 20:51:11.602527000, delta=2075266009473000 ns, racy<=2500000000 ns
2020-05-22 21:19:28,607 [Worker-1: Decoration Calculation] DEBUG o.e.j.i.storage.file.FileSnapshot - file=C:\Program Files\Git\etc\gitconfig, is unmodified
.......
2020-05-22 21:19:28,677 [Worker-7: Building Workspace] INFO  o.e.m.c.i.l.LifecycleMappingFactory - Using org.eclipse.m2e.jdt.JarLifecycleMapping lifecycle mapping for MavenProject: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT @ D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml.
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory - Loaded lifecycle mapping in 77 ms for MavenProject: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT @ D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml.
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory - MY PROJECT B is configured by :
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.eclipse.m2e.jdt.javaConfigurator
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.maven.ide.eclipse.configuration.wtp.java.unsupportedDependencyTypeConfigurator
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.eclipse.m2e.wtp.jpa.configurator.jdt
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.maven.ide.eclipse.configuration.wtp.utility.configurator
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.maven.ide.eclipse.configuration.wtp.webfragment.configurator
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.sonatype.m2e.mavenarchiver.jararchiverconfigurator
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.eclipse.m2e.wtp.jaxrs.configurator
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.p.r.DefaultMavenDependencyResolver - Resolving dependencies for P/MY PROJECT B: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT
2020-05-22 21:19:28,678 [Worker-7: Building Workspace] DEBUG o.e.m.c.internal.embedder.MavenImpl - Reading Maven project: D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml
2020-05-22 21:19:28,689 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.c.DefaultDependencyCollector - Dependency collection stats: {ConflictMarker.analyzeTime=288800, ConflictMarker.markTime=102300, ConflictMarker.nodeCount=328, ConflictIdSorter.graphTime=336300, ConflictIdSorter.topsortTime=260900, ConflictIdSorter.conflictIdCount=88, ConflictIdSorter.conflictIdCycleCount=48, ConflictResolver.totalTime=3849800, ConflictResolver.conflictItemCount=309, DefaultDependencyCollector.collectTime=5078800, DefaultDependencyCollector.transformTime=4849700}
2020-05-22 21:19:28,697 [Worker-7: Building Workspace] INFO  o.e.m.c.i.p.WorkspaceClassifierResolverManager - Resolving P/MY PROJECT A: com.my.company:MYPROJECTAARTIFACTID:1.0.1-SNAPSHOT with classifier  to /MY PROJECT A/target/classes
2020-05-22 21:19:28,739 [Worker-7: Building Workspace] DEBUG o.e.m.c.internal.embedder.MavenImpl - Read Maven project: D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml in 61 ms
2020-05-22 21:19:28,739 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.p.r.DefaultMavenDependencyResolver - Resolved dependencies for P/MY PROJECT B: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT in 61 ms
2020-05-22 21:19:28,740 [Worker-7: Building Workspace] DEBUG o.e.a.i.i.DefaultLocalRepositoryProvider - Using manager EnhancedLocalRepositoryManager with priority 10.0 for D:\MAVEN_REPONEW
2020-05-22 21:19:28,741 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory - Loading lifecycle mapping for MavenProject: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT @ D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml.
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] INFO  o.e.m.c.i.l.LifecycleMappingFactory - Using org.eclipse.m2e.jdt.JarLifecycleMapping lifecycle mapping for MavenProject: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT @ D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml.
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory - Loaded lifecycle mapping in 63 ms for MavenProject: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT @ D:\LOCALGITREPOS\CYCLE_2019\MYPROJECTBARTIFACTID\MY PROJECT B\pom.xml.
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory - MY PROJECT B is configured by :
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.eclipse.m2e.jdt.javaConfigurator
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.maven.ide.eclipse.configuration.wtp.java.unsupportedDependencyTypeConfigurator
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.eclipse.m2e.wtp.jpa.configurator.jdt
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.maven.ide.eclipse.configuration.wtp.utility.configurator
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.maven.ide.eclipse.configuration.wtp.webfragment.configurator
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.sonatype.m2e.mavenarchiver.jararchiverconfigurator
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.l.LifecycleMappingFactory -  - org.eclipse.m2e.wtp.jaxrs.configurator
2020-05-22 21:19:28,804 [Worker-7: Building Workspace] DEBUG o.e.m.c.i.p.r.DefaultMavenDependencyResolver - Resolving dependencies for P/MY PROJECT B: com.my.company:MYPROJECTBARTIFACTID:1.0.1-SNAPSHOT
................

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已将示例项目添加到 github (https://github.com/simpleusr/eclipseproblem) 以重现问题。最新的 eclipse 版本也失败了：2020-03 (4.15.0) Build id: 20200313-1211

【问题讨论】：

“我怎样才能在最新的 Eclipse 版本中达到同样的效果？” ← 至少你必须为此安装最新的 Eclipse 版本。使用过时的软件也很糟糕。请展示一个最小示例以在当前 Eclipse 版本中重现您的问题（由于涉及两个项目和多个文件，请将其放入公共 Git 存储库并链接到它）。
@howlger 感谢您的回复。根据您的要求，我在 github.com/simpleusr/eclipseproblem 添加了一个最小的复制器项目。请注意，最新版本 2020-03 (4.15.0) Build id: 20200313-1211 也会失败。我附上了两个版本的 m2e 日志。谢谢...
Eclipse 允许编译多个具有循环依赖关系的项目。但是在这里，解决（Maven）依赖关系会导致无限循环，这是另一回事。由于 Maven 不允许循环依赖，你也不能从命令行构建它，对吧？在 Eclipse 中，它可以在没有无效依赖项和手动配置 Java Build Path 的情况下工作。是否需要使用 Maven（在命令行上）构建项目，或者您是否只想（误用）使用 Maven 来管理依赖项？
@howlger 感谢您的回复。让我简要介绍一下导致这种丑陋情况的原因。在我们的代码库中，有 20 多个具有循环依赖关系的高度耦合项目，所有这些项目都是相当古老（超过 20 年）单体系统的基础架构组件。以前，项目构建是在代码提交后通过 eclipse jar 导出在开发人员计算机上本地执行的。一个现代化项目开始了，最重要的问题是通过标准构建工具执行服务器端构建，该工具恰好是 maven...
@howlger 再次感谢您的宝贵建议。所以据我了解，在以后的版本中没有办法保持旧的（可能是错误的）行为？我仍然想知道霓虹灯是如何处理这个问题的......顺便说一下，如果你愿意，你可以发布你的 cmets 作为我接受的答案。问候

标签： eclipse m2eclipse

【解决方案1】：

Eclipse 允许编译具有循环依赖关系的多个项目。但在这里，解决 Maven 依赖项会导致无限循环，这是另一回事。为了解决和下载依赖项，Eclipse 使用了 Eclipse IDE 附带的嵌入式 Maven。

由于Maven 不允许循环依赖，你也不能从命令行构建它。在 Eclipse 中，通过手动在 Java 构建路径中添加另一个项目并允许 Java 编译器的循环依赖，它可以在没有与 pom.xml 文件中的另一个项目的无效 Maven 依赖关系的情况下工作。但是这些手动设置将在 Maven > Update Project... 上被覆盖。

如果您想使用 Maven 来构建您的项目，您有两种选择：

将所有内容放入一个单个 Maven 项目，可能包含多个源文件夹。您可以在后处理步骤中将构建的 JAR 拆分为多个 JAR。这与多个循环相互依赖的项目具有相同的缺点：如果不是所有依赖项的整个代码都在类路径上，则运行时可能会丢失东西。
消除循环。根据我的经验，这是我的建议，因为从长远来看，投入的时间（可能是几周）会得到回报（而且模块化代码比意大利面条式代码更有趣）。

【讨论】：