Maven获取不到依赖信息，虽然jar已经到位

Question

在构建我的项目期间，我从 Ant/Maven 收到以下错误:

BUILD FAILED
C:\Users\kmilyutin\git\siamprofiler\classpath.build.xml:41: The following error occurred while executing this line:
C:\Users\kmilyutin\git\siamprofiler\classpath.build.xml:33: Unable to resolve artifact: Unable to get dependency information: Unable to read the metadata file for artifact 'commons-beanutils:commons-beanutils:jar': Cannot find parent: org.apache.commons:commons-parent for project: commons-beanutils:commons-beanutils:jar:1.8.0 for project commons-beanutils:commons-beanutils:jar:1.8.0
  commons-beanutils:commons-beanutils:jar:1.8.0

同时，与commons-beanutils关联的文件在存储库中:C:\Users\kmilyutin\.m2\repository\commons-beanutils\commons-beanutils\1.8 .0有人可以帮助解决这个问题吗？

更新:我尝试删除目录 .m2\repository\commons-beanutils\ 并重新构建。 Maven 给了我同样的错误，但现在 1.8.0\ 目录中只有 2 个文件:commons-beanutils-1.8.0.pom 和 commons -beanutils-1.8.0.pom.sha1。尽管我可以在中央 Maven 存储库中找到它，但无论出于何种原因，jar 文件都丢失了。

这是调试输出:

BUILD FAILED
C:\Users\kmilyutin\git\siamprofiler\classpath.build.xml:41: The following error occurred while executing this line:
C:\Users\kmilyutin\git\siamprofiler\classpath.build.xml:33: Unable to resolve artifact: Unable to get dependency information: Unable to read the metadata file for artifact 'commons-beanutils:commons-beanutils:jar': Cannot find parent: org.apache.commons:commons-parent for project: commons-beanutils:commons-beanutils:jar:1.8.0 for project commons-beanutils:commons-beanutils:jar:1.8.0
  commons-beanutils:commons-beanutils:jar:1.8.0

from the specified remote repositories:
  central (http://repo1.maven.org/maven2),
  maven2-repository.dev.java.net (http://download.java.net/maven/2/),
  jboss-public-repository-group (https://repository.jboss.org/nexus/content/groups/public/)

Path to dependency: 
    1) com.sivis:siamprofiler:war:2.7.3-SNAPSHOT
    2) org.richfaces.framework:richfaces-api:jar:3.3.5-SNAPSHOT


    at org.apache.maven.artifact.ant.DependenciesTask.doExecuteResolution(DependenciesTask.java:268)
    at org.apache.maven.artifact.ant.DependenciesTask.doExecute(DependenciesTask.java:168)
    at org.apache.maven.artifact.ant.AbstractArtifactTask.execute(AbstractArtifactTask.java:751)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:398)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.Target.execute(Target.java:390)
    at org.apache.tools.ant.Target.performTasks(Target.java:411)
    at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
    at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    at org.apache.tools.ant.Main.runBuild(Main.java:809)
    at org.apache.tools.ant.Main.startAnt(Main.java:217)
    at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
    at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)
Caused by: org.apache.maven.artifact.resolver.ArtifactResolutionException: Unable to get dependency information: Unable to read the metadata file for artifact 'commons-beanutils:commons-beanutils:jar': Cannot find parent: org.apache.commons:commons-parent for project: commons-beanutils:commons-beanutils:jar:1.8.0 for project commons-beanutils:commons-beanutils:jar:1.8.0
  commons-beanutils:commons-beanutils:jar:1.8.0

from the specified remote repositories:
  central (http://repo1.maven.org/maven2),
  maven2-repository.dev.java.net (http://download.java.net/maven/2/),
  jboss-public-repository-group (https://repository.jboss.org/nexus/content/groups/public/)

Path to dependency: 
    1) com.sivis:siamprofiler:war:2.7.3-SNAPSHOT
    2) org.richfaces.framework:richfaces-api:jar:3.3.5-SNAPSHOT


    at org.apache.maven.artifact.resolver.DefaultArtifactCollector.recurse(DefaultArtifactCollector.java:430)
    at org.apache.maven.artifact.resolver.DefaultArtifactCollector.recurse(DefaultArtifactCollector.java:435)
    at org.apache.maven.artifact.resolver.DefaultArtifactCollector.collect(DefaultArtifactCollector.java:74)
    at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolveTransitively(DefaultArtifactResolver.java:316)
    at org.apache.maven.artifact.ant.DependenciesTask.doExecuteResolution(DependenciesTask.java:263)
    ... 32 more
Caused by: org.apache.maven.artifact.metadata.ArtifactMetadataRetrievalException: Unable to read the metadata file for artifact 'commons-beanutils:commons-beanutils:jar': Cannot find parent: org.apache.commons:commons-parent for project: commons-beanutils:commons-beanutils:jar:1.8.0 for project commons-beanutils:commons-beanutils:jar:1.8.0
    at org.apache.maven.project.artifact.MavenMetadataSource.retrieveRelocatedProject(MavenMetadataSource.java:200)
    at org.apache.maven.project.artifact.MavenMetadataSource.retrieveRelocatedArtifact(MavenMetadataSource.java:94)
    at org.apache.maven.artifact.resolver.DefaultArtifactCollector.recurse(DefaultArtifactCollector.java:387)
    ... 36 more
Caused by: org.apache.maven.project.ProjectBuildingException: Cannot find parent: org.apache.commons:commons-parent for project: commons-beanutils:commons-beanutils:jar:1.8.0 for project commons-beanutils:commons-beanutils:jar:1.8.0
    at org.apache.maven.project.DefaultMavenProjectBuilder.assembleLineage(DefaultMavenProjectBuilder.java:1396)
    at org.apache.maven.project.DefaultMavenProjectBuilder.buildInternal(DefaultMavenProjectBuilder.java:823)
    at org.apache.maven.project.DefaultMavenProjectBuilder.buildFromRepository(DefaultMavenProjectBuilder.java:255)
    at org.apache.maven.project.artifact.MavenMetadataSource.retrieveRelocatedProject(MavenMetadataSource.java:163)
    ... 38 more
Caused by: org.apache.maven.project.InvalidProjectModelException: Parse error reading POM. Reason: end tag not allowed in epilog but got / (position: END_TAG seen ...</properties>\r\n\r\n</project>\r\n   </... @639:6)  for project org.apache.commons:commons-parent at C:\Users\kmilyutin\.m2\repository\org\apache\commons\commons-parent\11\commons-parent-11.pom
    at org.apache.maven.project.DefaultMavenProjectBuilder.readModel(DefaultMavenProjectBuilder.java:1610)
    at org.apache.maven.project.DefaultMavenProjectBuilder.readModel(DefaultMavenProjectBuilder.java:1571)
    at org.apache.maven.project.DefaultMavenProjectBuilder.findModelFromRepository(DefaultMavenProjectBuilder.java:562)
    at org.apache.maven.project.DefaultMavenProjectBuilder.assembleLineage(DefaultMavenProjectBuilder.java:1392)
    ... 41 more
Caused by: org.codehaus.plexus.util.xml.pull.XmlPullParserException: end tag not allowed in epilog but got / (position: END_TAG seen ...</properties>\r\n\r\n</project>\r\n   </... @639:6) 
    at org.codehaus.plexus.util.xml.pull.MXParser.parseEpilog(MXParser.java:1594)
    at org.codehaus.plexus.util.xml.pull.MXParser.nextImpl(MXParser.java:1405)
    at org.codehaus.plexus.util.xml.pull.MXParser.next(MXParser.java:1105)
    at org.apache.maven.model.io.xpp3.MavenXpp3Reader.parseModel(MavenXpp3Reader.java:2133)
    at org.apache.maven.model.io.xpp3.MavenXpp3Reader.read(MavenXpp3Reader.java:3912)
    at org.apache.maven.project.DefaultMavenProjectBuilder.readModel(DefaultMavenProjectBuilder.java:1606)
    ... 44 more

Total time: 5 seconds

这里是classpath.build.xml的一部分(第33行是artifact:dependencies标签):

<target name="resolve-dependencies" depends="checkTimestamps,mvn-configure"
            unless="${dependencies-resolved}">
        <macrodef name="resolve-scoped-dependencies" xmlns:artifact="urn:maven-artifact-ant">
            <attribute name="scope" />
            <sequential>
                <artifact:dependencies pathId="@{scope}.classpath" filesetId="@{scope}.fileset" useScope="@{scope}" >
                    <pom refid="maven.project" />
                    <localRepository refid="local.repository" />
                </artifact:dependencies>
                <pathconvert property="@{scope}.p" refid="@{scope}.fileset" pathsep="," />
                <echo file="target/@{scope}.fileset.txt">${@{scope}.p}</echo>
            </sequential>
        </macrodef>
        <resolve-scoped-dependencies scope="compile" />
        <resolve-scoped-dependencies scope="runtime" />
        <resolve-scoped-dependencies scope="provided" />
        <resolve-scoped-dependencies scope="system" />
        <resolve-scoped-dependencies scope="test" />
    </target>

Answer 1

消息中写明了原因:

Cannot find parent: org.apache.commons:commons-parent for project: commons-beanutils:commons-beanutils:jar:1.8.0

为了能够找出依赖关系，maven 不仅需要实际的 Artifact 元数据，还需要依赖元数据。这就是您所缺少的。

自 commons-parent 11 required by commons-beanutils 1.8在maven central repo ，通过与 Maven Central 的正确网络连接重试应该可以解决此问题。

但是，如果没有，请在打开调试 (mvn -X) 的情况下发布完整输出。

---

编辑:现在有了调试输出，我们可以看到

C:\Users\kmilyutin.m2\repository\org\apache\commons\commons-parent\11\commons-parent-11.pom

坏了:

org.apache.maven.project.InvalidProjectModelException: Parse error reading POM.
Reason: end tag not allowed in epilog but got / (position: END_TAG seen ...</properties>\r\n\r\n</project>\r\n   </... @639:6)
for project org.apache.commons:commons-parent
at C:\Users\kmilyutin\.m2\repository\org\apache\commons\commons-parent\11\commons-parent-11.pom

作为第一步，从消息中给出的路径中的本地存储库中删除该文件，然后重试构建。