Java 安装maven时没有指定目标异常

看起来这是设置maven的一个重复挑战，但我在这方面也有自己的挑战。。。！我是maven和java的新手，非常感谢您的帮助

这是我目前在MacOS v10.15.7上的设置

正如maven所建议的，我首先定义我的JAVA_主页（在OSX中不是默认设置的）

然后我继续下载Maven 3.6.3，并在

/Users/byc/Downloads/apache-Maven-3.6.3

上创建了一个文件夹，运行以下命令

export PATH=/Users/byc/Downloads/apache-maven-3.6.3/bin:$PATH
mvn --verison
-bash: mvn: command not found

当我运行mvn-e时，我得到了以下信息。这是否意味着Maven没有正确绑定到

$PATH

mvn -e
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.059 s
[INFO] Finished at: 2020-12-01T19:03:43Z
[INFO] ------------------------------------------------------------------------
[ERROR] No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy. -> [Help 1]
org.apache.maven.lifecycle.NoGoalSpecifiedException: No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy.
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:97)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:567)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
[ERROR] 
[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/NoGoalSpecifiedException

mvn-e
[信息]错误堆栈跟踪已打开。
[信息]正在扫描项目。。。
[信息]------------------------------------------------------------------------
[信息]生成失败
[信息]------------------------------------------------------------------------
[信息]总时间：0.059秒
[信息]完成时间：2020-12-01T19:03:43Z
[信息]------------------------------------------------------------------------
[错误]尚未为此生成指定任何目标。必须以以下格式指定有效的生命周期阶段或目标：或：[：]：。可用的生命周期阶段包括：验证、初始化、生成源、流程源、生成资源、流程资源、编译、流程类、生成测试源、流程测试源、生成测试资源、流程测试资源、测试编译、流程测试类、测试、准备包、包、预集成测试、，集成测试、集成后测试、验证、安装、部署、预清理、清理、清理后、预站点、站点、站点后、站点部署。->[帮助1]
org.apache.maven.lifecycle.nogoalsspecifiedException:尚未为此构建指定任何目标。必须以以下格式指定有效的生命周期阶段或目标：或：[：]：。可用的生命周期阶段包括：验证、初始化、生成源、流程源、生成资源、流程资源、编译、流程类、生成测试源、流程测试源、生成测试资源、流程测试资源、测试编译、流程测试类、测试、准备包、包、预集成测试、，集成测试、集成后测试、验证、安装、部署、预清理、清理、清理后、预站点、站点、站点后、站点部署。
位于org.apache.maven.lifecycle.internal.LifecycleStarter.execute（LifecycleStarter.java:97）
在org.apache.maven.DefaultMaven.doExecute（DefaultMaven.java:305）
在org.apache.maven.DefaultMaven.doExecute（DefaultMaven.java:192）
位于org.apache.maven.DefaultMaven.execute（DefaultMaven.java:105）
位于org.apache.maven.cli.MavenCli.execute（MavenCli.java:957）
位于org.apache.maven.cli.MavenCli.doMain（MavenCli.java:289）
位于org.apache.maven.cli.MavenCli.main（MavenCli.java:193）
位于jdk.internal.reflect.NativeMethodAccessorImpl.invoke0（本机方法）
位于jdk.internal.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:62）
在jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）
位于java.lang.reflect.Method.invoke（Method.java:567）
位于org.codehaus.plexus.classworlds.launcher.launcher.launchEnhanced（launcher.java:282）
位于org.codehaus.plexus.classworlds.launcher.launcher.launch（launcher.java:225）
在org.codehaus.plexus.classworlds.launcher.launcher.main上使用exitcode（launcher.java:406）
位于org.codehaus.plexus.classworlds.launcher.launcher.main（launcher.java:347）
[错误]
[错误]使用-X开关重新运行Maven以启用完整调试日志记录。
[错误]
[错误]有关错误和可能的解决方案的更多信息，请阅读以下文章：
[错误][帮助1]http://cwiki.apache.org/confluence/display/MAVEN/NoGoalSpecifiedException

有几件事：

我不知道为什么Maven文档继续告诉人们设置

JAVA\u HOME

。如果

javac

（是的，

javac

，不知道为什么）在您的路径中（这通常意味着

java

也在您的路径中），那么这是不必要的

您将

version

拼错为

verison

，这就是您收到

-bash:mvn:command not found

的原因

你指定了，所以Maven不知道该怎么办

---

不，这意味着您没有告诉Maven做任何事情，比如

mvn compile

。Maven有一组特定的目标，您可以在每次执行时指定一个或多个目标。可用的目标可能会受到与生命周期中特定步骤相关联的“插件”的影响。最简单的目标是“干净”

mvn clean

从您的工作区中删除特定类型的工件，这些工件可以在构建过程中稍后下载或生成。（最后请注意，

/usr/libexec/java_home

是在macOS上查找特定JDK安装根目录的最佳方法。）唉，拼写错误！它现在已启动并运行

mvn-version。Apache Maven 3.6.3 Maven home:/Users/byc/Downloads/Apache-Maven-3.6.3 Java版本：12.0.2，供应商：Oracle公司，运行时：/Library/Java/JavaVirtualMachines/openjdk-12.0.2.jdk/Contents/home默认区域设置：en_GB，平台编码：UTF-8操作系统名称：“mac OS x”，版本：“10.15.7”，arch:“x86_64”，系列：“mac”

javac你的观点有什么用？由于过去的安装，我确实有几个JDK正在运行

/usr/libexec/java_home

已经给我指出了当前的一个：）@byc我猜在没有任何信息的情况下，

javac

而不是

java

的测试是看Maven是否可以访问JDK而不是JRE。我进一步推测，这是出于历史原因，不再相关：也许

maven编译器插件

比现在更紧密地集成到maven内核中，也许在遥远的过去，它需要向

javac

抛售。或者，你知道，输入错误。看起来不太可能，但我需要运行

export PATH=/Users/byc/Dow吗
mvn -e
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.059 s
[INFO] Finished at: 2020-12-01T19:03:43Z
[INFO] ------------------------------------------------------------------------
[ERROR] No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy. -> [Help 1]
org.apache.maven.lifecycle.NoGoalSpecifiedException: No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy.
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:97)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:567)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
[ERROR] 
[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/NoGoalSpecifiedException