Maven eclipse 打包“pom”不工作

Question

我正在使用 Eclipse Mars (4.5) 和 Maven 3.3.3。

最近，我对一个项目 Java 8 (SE) 进行了 Maven 更新，突然，Eclipse 不希望我的pom.xml<packaging>jar</packaging>中的有效，而是希望我将打包更改为pom。为什么我不能把它留在jar中？

此外，在概述中，封装选择被禁用。

当从控制台运行 Maven（带有 jar 打包）时，这就是我得到的：

[ERROR] [ERROR] Some problems were encountered while processing the POMs:
[ERROR] Child module C:\Users\Me\workspace\MyProject\? of C:\Users\Me\workspace\MyProject\pom.xml does not exist @
[ERROR] 'packaging' with value 'jar' is invalid. Aggregator projects require 'pom' as packaging. @ line 8, column 13
 @
[ERROR] The build could not read 1 project -> [Help 1]
org.apache.maven.project.ProjectBuildingException: Some problems were encountered while processing the POMs:
[ERROR] Child module C:\Users\Me\workspace\MyProject\? of C:\Users\Me\workspace\MyProject\pom.xml does not exist @
[ERROR] 'packaging' with value 'jar' is invalid. Aggregator projects require 'pom' as packaging. @ line 8, column 13

        at org.apache.maven.project.DefaultProjectBuilder.build(DefaultProjectBuilder.java:422)
        at org.apache.maven.graph.DefaultGraphBuilder.collectProjects(DefaultGraphBuilder.java:419)
        at org.apache.maven.graph.DefaultGraphBuilder.getProjectsForMavenReactor(DefaultGraphBuilder.java:410)
        at org.apache.maven.graph.DefaultGraphBuilder.build(DefaultGraphBuilder.java:83)
        at org.apache.maven.DefaultMaven.buildGraph(DefaultMaven.java:491)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:219)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:862)
        at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:286)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:197)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
        at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
        at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
[ERROR]
[ERROR]   The project MyProject:model:0.2 (C:\Users\Me\workspace\MyProject\pom.xml) has 2 errors
[ERROR]     Child module C:\Users\Me\workspace\MyProject\? of C:\Users\Me\workspace\MyProject\pom.xml does not exist
[ERROR]     'packaging' with value 'jar' is invalid. Aggregator projects require 'pom' as packaging. @ line 8, column 13

有人可以帮助我吗？至少在重新启用 jar 包装方面。谢谢。

编辑：确实，不知何故我的pom.xml添加了一些新行（我不知道为什么或如何）：

<modules>
    <module>?</module>
</modules>

这就是导致问题的原因。删除后问题就解决了，谢谢！

Answer 1

因为如果你的 pom 声明了模块，它就是一个“聚合器 POM”——聚合器模块必须是pom. 这就是您在日志中收到以下错误的原因：

[ERROR] 'packaging' with value 'jar' is invalid. 
    Aggregator projects require 'pom' as packaging. @ line 8, column 13

您可以返回到从 pom.xml 中jar删除所有声明时的状态。<module>

请参阅多模块项目的文档。