maven - mvn idea :idea throws a NullPointerException

Question

当我尝试在我的项目中执行mvn idea:idea -X时。我面临一个特殊的问题-

> [ERROR] Failed to execute goal
> org.apache.maven.plugins:maven-idea-plugin:2.2.1:idea (default-cli) on
> project test-model: Execution default-cli of goal
> org.apache.maven.plugins:maven-idea-plugin:2.2.1:idea failed.
> NullPointerException -> [Help 1]
> org.apache.maven.lifecycle.LifecycleExecutionException: Failed to
> execute goal org.apache.maven.plugins:maven-idea-plugin:2.2.1:idea
> (default-cli) on project document-model: Execution default-cli of goal
> org.apache.maven.plugins:maven-idea-plugin:2.2.1:idea failed.
>         at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:212)
>         at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
>         at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
>         at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
>         at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
>         at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
>         at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
>         at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
>         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:863)
>         at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
>         at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
>         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)
> Caused by: org.apache.maven.plugin.PluginExecutionException: Execution
> default-cli of goal
> org.apache.maven.plugins:maven-idea-plugin:2.2.1:idea failed.
>         at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145)
>         at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
>         ... 20 more Caused by: java.lang.NullPointerException
>         at org.apache.maven.repository.legacy.DefaultWagonManager.connectWagon(DefaultWagonManager.java:244)
>         at org.apache.maven.repository.legacy.DefaultWagonManager.getRemoteFile(DefaultWagonManager.java:346)
>         at org.apache.maven.repository.legacy.DefaultWagonManager.getArtifact(DefaultWagonManager.java:110)
>         at org.apache.maven.repository.legacy.DefaultWagonManager.getArtifact(DefaultWagonManager.java:163)
>         at org.apache.maven.artifact.manager.DefaultWagonManager.getArtifact(DefaultWagonManager.java:155)
>         at org.apache.maven.plugin.idea.IdeaModuleMojo.resolveClassifiedArtifact(IdeaModuleMojo.java:966)
>         at org.apache.maven.plugin.idea.IdeaModuleMojo.resolveClassifier(IdeaModuleMojo.java:929)
>         at org.apache.maven.plugin.idea.IdeaModuleMojo.rewriteDependencies(IdeaModuleMojo.java:587)
>         at org.apache.maven.plugin.idea.IdeaModuleMojo.rewriteModule(IdeaModuleMojo.java:409)
>         at org.apache.maven.plugin.idea.IdeaMojo.rewriteModule(IdeaMojo.java:220)
>         at org.apache.maven.plugin.idea.IdeaMojo.execute(IdeaMojo.java:200)
>         at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
>         ... 21 more [ERROR]  [ERROR]  [ERROR] For more information about the errors and possible solutions, please read the following
> articles: [ERROR] [Help 1]
> http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException

此处的链接显示为-

This error is reported in case the execution of a plugin failed due to some unforeseen event. For example, uncatched runtime exceptions caused by the plugin will raise this error. You should report this problem to the maintainer of the plugin.

也不确定维护者，在此处寻求一些帮助。

更新1
遵循答案中@ A_Di-Matteo提到的步骤，我可以弄清楚该步骤中发生了故障

mvn idea:module

对我来说，具有类似的堆栈跟踪

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-idea-plugin:2.2.1:module (default-cli) on project core: Execution default-cli of goal org.apache.maven.plugins:maven-idea-plugin:2.2.1:module failed. NullPointerException

再次将其带到重要点，是否有解决方法？

Answer 1

maven-idea-plugin 是退休的，自2013年以来一直没有维护(自2008年以来实际上是无效的)，因此与IDE新版本的任何不兼容都将阻止其使用。

如果出于某种原因您仍然通过idea:idea目标寻求帮助，但遇到错误，则可以尝试使用其他procedure:

mvn idea:clean
mvn idea:project    ---> it will create the .ipr file (core project info)
mvn idea:module     ---> it will create the .iml file (library info for the module)
mvn idea:workspace  ---> it will create the .iws file (personal workspace info)

最后三个命令实际上已经由idea:idea自动执行，但是它们可以帮助您进一步检查出现错误的位置，并希望进一步提示进行故障排除。但是，IDE将所有这些文件视为legacy files，因此，这又不是理想的过程。

但是，这又很麻烦:该插件很可能不再与较新版本的IDE兼容。

如果直接导入父pom.xml文件没有导入项目，则:

您可以将项目作为通用Java项目导入，然后convert it to Maven project

或者(在最坏的情况下)，您可以在IDE中创建一个新的Maven项目，然后逐步(复制并粘贴)重新创建一个不可能导入的项目:问题很可能会出现或者它可以正常工作如预期的那样。