我正在使用Maven 3.3.9。在学习maven时，我创建了一个演示项目并运行此命令以了解有关maven Compiler plugin的更多信息。
mvn help:describe -Dplugin =compiler
我收到以下错误：
INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building ex1 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-help-plugin:2.2:describe (default-cli) @ ex1 ---
Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-metadata.xml
Downloading: https://repo.maven.apache.org/maven2/org/codehaus/mojo/maven-metadata.xml
Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-metadata.xml (13 KB at 5.6 KB/sec)
Downloaded: https://repo.maven.apache.org/maven2/org/codehaus/mojo/maven-metadata.xml (20 KB at 7.3 KB/sec)
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Skipping ex1
[INFO] This project has been banned from the build due to previous failures.
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 3.684 s
[INFO] Finished at: 2017-03-15T13:00:59+05:30
[INFO] Final Memory: 13M/245M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-help-plugin:2.2:describe (default-cli) on project ex1: Plugin could not be found. If you believe it is correct, check your pluginGroups setting, and run with -U to update the remote configuration -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[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/MojoFailureException
查看构建失败，我运行了以下命令：
mvn clean install
我们可以看到一切都很顺利：
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building ex1 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ ex1 ---
[INFO] Deleting /Users/tiwaris/My Own Workspace/workspace/ex1/target
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ ex1 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/tiwaris/My Own Workspace/workspace/ex1/src/main/resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ ex1 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/tiwaris/My Own Workspace/workspace/ex1/target/classes
[INFO]
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ ex1 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/tiwaris/My Own Workspace/workspace/ex1/src/test/resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ ex1 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/tiwaris/My Own Workspace/workspace/ex1/target/test-classes
[INFO]
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ ex1 ---
[INFO] Surefire report directory: /Users/tiwaris/My Own Workspace/workspace/ex1/target/surefire-reports
-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running com.pg.AppTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.027 sec
Results :
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ ex1 ---
[INFO] Building jar: /Users/tiwaris/My Own Workspace/workspace/ex1/target/ex1-1.0-SNAPSHOT.jar
[INFO]
[INFO] --- maven-install-plugin:2.4:install (default-install) @ ex1 ---
[INFO] Installing /Users/tiwaris/My Own Workspace/workspace/ex1/target/ex1-1.0-SNAPSHOT.jar to /Users/tiwaris/.m2/repository/com/pg/ex1/1.0-SNAPSHOT/ex1-1.0-SNAPSHOT.jar
[INFO] Installing /Users/tiwaris/My Own Workspace/workspace/ex1/pom.xml to /Users/tiwaris/.m2/repository/com/pg/ex1/1.0-SNAPSHOT/ex1-1.0-SNAPSHOT.pom
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.785 s
[INFO] Finished at: 2017-03-15T13:02:49+05:30
[INFO] Final Memory: 17M/310M
[INFO] ------------------------------------------------------------------------
搜索更多，我想我们会删除整个.m2文件夹并重新开始。但是，仍然会出现此错误。是什么原因？
答案 0 :(得分：2)
您需要在等号前删除多余的空格：
mvn help:describe -Dplugin =compiler
^
应该是
mvn help:describe -Dplugin=compiler