我正在尝试为Solr设置学习排名插件位于此处： https://github.com/bloomberg/lucene-solr/tree/master-ltr-plugin-release/solr/contrib/ltr
我已经设置了Java JDK以及Apache Ant，因为这是插件用来编译的内容，我已经验证这两个设置都正确，因为它们的命令被识别。请注意，我在Windows 7上运行。
我按照该链接中列出的说明进行操作，但第一步甚至无法通过。我执行命令来编译＆＃34; ant dist＆＃34;和＆＃34;蚂蚁服务器＆＃34;我只是得到一个NullPointerException。我试过在根目录下编译，＆＃34; solr＆＃34;目录，以及＆＃34; ltr＆＃34;目录，但我每次都得到同样的错误。
我不确定这个插件是否已经过时或者我的设置中缺少某些问题，因为这些特定组件的问题似乎没有太多信息。希望我能找到一个可能知道这里出了什么问题的人。非常感谢任何输入！
哦，这是我在尝试编译时得到的错误消息：
C:\Users\aan7771\Desktop\SOLR-ML-PLUGIN\lucene-solr-master-ltr-plugin-release\so
lr>ant dist
Buildfile: C:\Users\aan7771\Desktop\SOLR-ML-PLUGIN\lucene-solr-master-ltr-plugin
-release\solr\build.xml
BUILD FAILED
C:\Users\aan7771\Desktop\SOLR-ML-PLUGIN\lucene-solr-master-ltr-plugin-release\so
lr\build.xml:39: The following error occurred while executing this line:
C:\Users\aan7771\Desktop\SOLR-ML-PLUGIN\lucene-solr-master-ltr-plugin-release\so
lr\common-build.xml:54: The following error occurred while executing this line:
C:\Users\aan7771\Desktop\SOLR-ML-PLUGIN\lucene-solr-master-ltr-plugin-release\lu
cene\module-build.xml:27: The following error occurred while executing this line
:
C:\Users\aan7771\Desktop\SOLR-ML-PLUGIN\lucene-solr-master-ltr-plugin-release\lu
cene\common-build.xml:542: java.lang.NullPointerException
at java.util.Arrays.stream(Arrays.java:5004)
at java.util.stream.Stream.of(Stream.java:1000)
at java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:
267)
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:
193)
at java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators
.java:948)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.ja
va:471)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:545)
at java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipelin
e.java:260)
at java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:438
)
at org.apache.tools.ant.util.ChainedMapper.lambda$mapFileName$1(ChainedM
apper.java:36)
at java.util.stream.ReduceOps$1ReducingSink.accept(ReduceOps.java:80)
at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.j
ava:1382)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.ja
va:471)
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java
:708)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.reduce(ReferencePipeline.java:484)
at org.apache.tools.ant.util.ChainedMapper.mapFileName(ChainedMapper.jav
a:35)
at org.apache.tools.ant.util.CompositeMapper.lambda$mapFileName$0(Compos
iteMapper.java:32)
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:
193)
at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:
175)
at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.j
ava:1382)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.ja
va:471)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:545)
at java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipelin
e.java:260)
at java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:438
)
at org.apache.tools.ant.util.CompositeMapper.mapFileName(CompositeMapper
.java:33)
at org.apache.tools.ant.taskdefs.PathConvert.execute(PathConvert.java:36
3)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:292)
at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.jav
a:106)
at org.apache.tools.ant.Task.perform(Task.java:346)
at org.apache.tools.ant.Target.execute(Target.java:448)
at org.apache.tools.ant.helper.ProjectHelper2.parse(ProjectHelper2.java:
172)
at org.apache.tools.ant.taskdefs.ImportTask.importResource(ImportTask.ja
va:221)
at org.apache.tools.ant.taskdefs.ImportTask.execute(ImportTask.java:165)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:292)
at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.jav
a:106)
at org.apache.tools.ant.Task.perform(Task.java:346)
at org.apache.tools.ant.Target.execute(Target.java:448)
at org.apache.tools.ant.helper.ProjectHelper2.parse(ProjectHelper2.java:
172)
at org.apache.tools.ant.taskdefs.ImportTask.importResource(ImportTask.ja
va:221)
at org.apache.tools.ant.taskdefs.ImportTask.execute(ImportTask.java:165)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:292)
at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.jav
a:106)
at org.apache.tools.ant.Task.perform(Task.java:346)
at org.apache.tools.ant.Target.execute(Target.java:448)
at org.apache.tools.ant.helper.ProjectHelper2.parse(ProjectHelper2.java:
172)
at org.apache.tools.ant.taskdefs.ImportTask.importResource(ImportTask.ja
va:221)
at org.apache.tools.ant.taskdefs.ImportTask.execute(ImportTask.java:165)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:292)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.jav
a:106)
at org.apache.tools.ant.Task.perform(Task.java:346)
at org.apache.tools.ant.Target.execute(Target.java:448)
at org.apache.tools.ant.helper.ProjectHelper2.parse(ProjectHelper2.java:
183)
at org.apache.tools.ant.ProjectHelper.configureProject(ProjectHelper.jav
a:93)
at org.apache.tools.ant.Main.runBuild(Main.java:824)
at org.apache.tools.ant.Main.startAnt(Main.java:228)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:283)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:101)
Total time: 0 seconds
C:\Users\aan7771\Desktop\SOLR-ML-PLUGIN\lucene-solr-master-ltr-plugin-release\so
lr>