问题描述
根据 the Maven release history，应该可以在 JDK 7 上运行任何最新版本的 Maven（在撰写本文时）。但是，当我尝试在我的 Ubuntu 21.04 机器上这样做时，我得到错误： java.lang.UnsupportedClassversionError: com/google/inject/Module : Unsupported major.minor version 52.0。
即使在不包含任何 Java 文件或 mvn 文件的目录中运行没有任何参数的 pom.xml 时也会发生这种情况。
Maven 信息：
└─❯ mvn -version
Apache Maven 3.6.3
Maven home: /usr/share/maven
Java version: 1.7.0_80,vendor: Oracle Corporation,runtime: /home/jqno/.jabba/jdk/1.7.80-oracle/jre
Default locale: en_US,platform encoding: UTF-8
OS name: "linux",version: "5.11.0-16-generic",arch: "amd64",family: "unix"
（我还安装了 Zulu 1.7.292 和 OpenJDK；那里的行为是相同的。）
完整的堆栈跟踪：
└─❯ mvn clean
---------------------------------------------------
constituent[0]: file:/usr/share/maven/conf/logging/
constituent[1]: file:/usr/share/maven/lib/commons-lang3.jar
constituent[2]: file:/usr/share/maven/lib/sisu-plexus.jar
constituent[3]: file:/usr/share/maven/lib/maven-core-3.x.jar
constituent[4]: file:/usr/share/maven/lib/maven-shared-utils.jar
constituent[5]: file:/usr/share/maven/lib/sisu-inject.jar
constituent[6]: file:/usr/share/maven/lib/jansi.jar
constituent[7]: file:/usr/share/maven/lib/plexus-component-annotations.jar
constituent[8]: file:/usr/share/maven/lib/plexus-interpolation.jar
constituent[9]: file:/usr/share/maven/lib/maven-settings-builder-3.x.jar
constituent[10]: file:/usr/share/maven/lib/aopalliance.jar
constituent[11]: file:/usr/share/maven/lib/wagon-provider-api.jar
constituent[12]: file:/usr/share/maven/lib/jsr250-api.jar
constituent[13]: file:/usr/share/maven/lib/slf4j-api.jar
constituent[14]: file:/usr/share/maven/lib/plexus-cipher.jar
constituent[15]: file:/usr/share/maven/lib/maven-slf4j-provider-3.x.jar
constituent[16]: file:/usr/share/maven/lib/maven-resolver-transport-wagon.jar
constituent[17]: file:/usr/share/maven/lib/wagon-file.jar
constituent[18]: file:/usr/share/maven/lib/plexus-sec-dispatcher.jar
constituent[19]: file:/usr/share/maven/lib/maven-resolver-provider-3.x.jar
constituent[20]: file:/usr/share/maven/lib/jcl-over-slf4j.jar
constituent[21]: file:/usr/share/maven/lib/wagon-http-shaded.jar
constituent[22]: file:/usr/share/maven/lib/maven-compat-3.x.jar
constituent[23]: file:/usr/share/maven/lib/guice-no-aop.jar
constituent[24]: file:/usr/share/maven/lib/maven-artifact-3.x.jar
constituent[25]: file:/usr/share/maven/lib/guava.jar
constituent[26]: file:/usr/share/maven/lib/maven-resolver-connector-basic.jar
constituent[27]: file:/usr/share/maven/lib/commons-cli.jar
constituent[28]: file:/usr/share/maven/lib/maven-builder-support-3.x.jar
constituent[29]: file:/usr/share/maven/lib/maven-resolver-api.jar
constituent[30]: file:/usr/share/maven/lib/plexus-utils.jar
constituent[31]: file:/usr/share/maven/lib/maven-settings-3.x.jar
constituent[32]: file:/usr/share/maven/lib/maven-resolver-util.jar
constituent[33]: file:/usr/share/maven/lib/maven-resolver-impl.jar
constituent[34]: file:/usr/share/maven/lib/cdi-api.jar
constituent[35]: file:/usr/share/maven/lib/maven-resolver-spi.jar
constituent[36]: file:/usr/share/maven/lib/maven-embedder-3.x.jar
constituent[37]: file:/usr/share/maven/lib/maven-repository-Metadata-3.x.jar
constituent[38]: file:/usr/share/maven/lib/commons-io.jar
constituent[39]: file:/usr/share/maven/lib/maven-model-builder-3.x.jar
constituent[40]: file:/usr/share/maven/lib/maven-plugin-api-3.x.jar
constituent[41]: file:/usr/share/maven/lib/maven-model-3.x.jar
constituent[42]: file:/usr/share/maven/lib/javax.inject.jar
---------------------------------------------------
Exception in thread "main" java.lang.UnsupportedClassversionError: com/google/inject/Module : Unsupported major.minor version 52.0
at java.lang.classLoader.defineClass1(Native Method)
at java.lang.classLoader.defineClass(ClassLoader.java:800)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.urlclassloader.defineClass(urlclassloader.java:449)
at java.net.urlclassloader.access$100(urlclassloader.java:71)
at java.net.urlclassloader$1.run(urlclassloader.java:361)
at java.net.urlclassloader$1.run(urlclassloader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.urlclassloader.findClass(urlclassloader.java:354)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf(ClassRealm.java:425)
at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:42)
at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:247)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239)
at org.apache.maven.cli.MavenCli.container(MavenCli.java:636)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:282)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
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)
看起来好像在某个地方，Maven 尝试加载一个为 JDK8 编译的类，因为它抱怨 52.0 的类版本不受支持。但是我找不到哪个类，或者为什么 Maven 首先尝试加载它。我在 Google 上能找到的所有内容似乎都不相关。
这是怎么回事？我该如何解决这个问题？
更新
我解压了 /usr/share/maven/lib/guice-no-aop.jar 文件并运行了 javap -verbose com.google.inject.Module，它确实有 52.0.0 版本。我不知道该文件是如何到达那里的（我认为它是由 apt install maven 安装的，但我不确定）。
解决方法
这里的问题是 Ubuntu 重新打包了 Maven，结果产生了这个问题。
如下所示，如果您通过以下方式检查版本：
mvn --version
Apache Maven 3.6.3
Maven home: /usr/share/maven
Java version: 1.7.0_80,vendor: Oracle Corporation,runtime: /home/jqno/.jabba/jdk/1.7.80-oracle/jre
Default locale: en_US,platform encoding: UTF-8
OS name: "linux",version: "5.11.0-16-generic",arch: "amd64",family: "unix"
这表明您未使用 Apache Maven。
如果您在普通命令行上执行此操作并通过 https://maven.apache.org/download.cgi 安装 Apache Maven，您将获得如下输出：
Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: /Users/XXX/tools/maven
Java version: 1.7.0_302,vendor: Azul Systems,Inc.,runtime: /Users/khmarbaise/.sdkman/candidates/java/7.0.302-zulu/zulu-7.jdk/Contents/Home/jre
Default locale: en_GB,platform encoding: UTF-8
OS name: "mac os x",version: "10.14.6",arch: "x86_64",family: "mac"
最重要的部分是第一行：
Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
这是 Apache Maven。
第二，如果你仔细查看错误输出：
constituent[0]: file:/usr/share/maven/conf/logging/
constituent[1]: file:/usr/share/maven/lib/commons-lang3.jar
constituent[2]: file:/usr/share/maven/lib/sisu-plexus.jar
constituent[3]: file:/usr/share/maven/lib/maven-core-3.x.jar
constituent[4]: file:/usr/share/maven/lib/maven-shared-utils.jar
constituent[5]: file:/usr/share/maven/lib/sisu-inject.jar
constituent[6]: file:/usr/share/maven/lib/jansi.jar
constituent[7]: file:/usr/share/maven/lib/plexus-component-annotations.jar
constituent[8]: file:/usr/share/maven/lib/plexus-interpolation.jar
constituent[9]: file:/usr/share/maven/lib/maven-settings-builder-3.x.jar
constituent[10]: file:/usr/share/maven/lib/aopalliance.jar
constituent[11]: file:/usr/share/maven/lib/wagon-provider-api.jar
constituent[12]: file:/usr/share/maven/lib/jsr250-api.jar
constituent[13]: file:/usr/share/maven/lib/slf4j-api.jar
constituent[14]: file:/usr/share/maven/lib/plexus-cipher.jar
constituent[15]: file:/usr/share/maven/lib/maven-slf4j-provider-3.x.jar
constituent[16]: file:/usr/share/maven/lib/maven-resolver-transport-wagon.jar
constituent[17]: file:/usr/share/maven/lib/wagon-file.jar
constituent[18]: file:/usr/share/maven/lib/plexus-sec-dispatcher.jar
constituent[19]: file:/usr/share/maven/lib/maven-resolver-provider-3.x.jar
constituent[20]: file:/usr/share/maven/lib/jcl-over-slf4j.jar
constituent[21]: file:/usr/share/maven/lib/wagon-http-shaded.jar
constituent[22]: file:/usr/share/maven/lib/maven-compat-3.x.jar
constituent[23]: file:/usr/share/maven/lib/guice-no-aop.jar
constituent[24]: file:/usr/share/maven/lib/maven-artifact-3.x.jar
constituent[25]: file:/usr/share/maven/lib/guava.jar
constituent[26]: file:/usr/share/maven/lib/maven-resolver-connector-basic.jar
constituent[27]: file:/usr/share/maven/lib/commons-cli.jar
constituent[28]: file:/usr/share/maven/lib/maven-builder-support-3.x.jar
constituent[29]: file:/usr/share/maven/lib/maven-resolver-api.jar
constituent[30]: file:/usr/share/maven/lib/plexus-utils.jar
constituent[31]: file:/usr/share/maven/lib/maven-settings-3.x.jar
constituent[32]: file:/usr/share/maven/lib/maven-resolver-util.jar
constituent[33]: file:/usr/share/maven/lib/maven-resolver-impl.jar
constituent[34]: file:/usr/share/maven/lib/cdi-api.jar
constituent[35]: file:/usr/share/maven/lib/maven-resolver-spi.jar
constituent[36]: file:/usr/share/maven/lib/maven-embedder-3.x.jar
constituent[37]: file:/usr/share/maven/lib/maven-repository-metadata-3.x.jar
constituent[38]: file:/usr/share/maven/lib/commons-io.jar
constituent[39]: file:/usr/share/maven/lib/maven-model-builder-3.x.jar
constituent[40]: file:/usr/share/maven/lib/maven-plugin-api-3.x.jar
constituent[41]: file:/usr/share/maven/lib/maven-model-3.x.jar
constituent[42]: file:/usr/share/maven/lib/javax.inject.jar
你可以看到这样的事情：
constituent[3]: file:/usr/share/maven/lib/maven-core-3.x.jar
..
constituent[25]: file:/usr/share/maven/lib/guice-no-aop.jar
如果您查看原始 Apache Maven lib directory 文件，则文件如下所示：
javaee (master *)$ ls -la ~/tools/apache-maven-3.6.3/lib/
total 21000
drwxr-xr-x 65 khmarbaise staff 2080 Nov 7 2019 .
drwxr-xr-x 9 khmarbaise staff 288 Nov 21 2019 ..
-rw-r--r-- 1 khmarbaise staff 44908 Nov 7 2019 cdi-api-1.0.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 cdi-api.license
-rw-r--r-- 1 khmarbaise staff 53820 Nov 7 2019 commons-cli-1.4.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 commons-cli.license
-rw-r--r-- 1 khmarbaise staff 208700 Nov 7 2019 commons-io-2.5.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 commons-io.license
-rw-r--r-- 1 khmarbaise staff 501879 Nov 7 2019 commons-lang3-3.8.1.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 commons-lang3.license
drwxr-xr-x 3 khmarbaise staff 96 Nov 7 2019 ext
-rw-r--r-- 1 khmarbaise staff 2591373 Nov 7 2019 guava-25.1-android.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 guava.license
-rw-r--r-- 1 khmarbaise staff 520662 Nov 7 2019 guice-4.2.1-no_aop.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 guice.license
-rw-r--r-- 1 khmarbaise staff 283858 Nov 7 2019 jansi-1.17.1.jar
drwxr-xr-x 10 khmarbaise staff 320 Nov 7 2019 jansi-native
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 jansi.license
-rw-r--r-- 1 khmarbaise staff 2497 Nov 7 2019 javax.inject-1.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 javax.inject.license
-rw-r--r-- 1 khmarbaise staff 16539 Nov 7 2019 jcl-over-slf4j-1.7.29.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 jcl-over-slf4j.license
-rw-r--r-- 1 khmarbaise staff 397115 Nov 7 2019 jsoup-1.12.1.jar
-rw-r--r-- 1 khmarbaise staff 1192 Nov 7 2019 jsoup.license
-rw-r--r-- 1 khmarbaise staff 5848 Nov 7 2019 jsr250-api-1.0.jar
-rw-r--r-- 1 khmarbaise staff 20545 Nov 7 2019 jsr250-api.license
-rw-r--r-- 1 khmarbaise staff 57824 Nov 7 2019 maven-artifact-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 14262 Nov 7 2019 maven-builder-support-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 287955 Nov 7 2019 maven-compat-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 633028 Nov 7 2019 maven-core-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 98096 Nov 7 2019 maven-embedder-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 215412 Nov 7 2019 maven-model-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 192302 Nov 7 2019 maven-model-builder-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 47035 Nov 7 2019 maven-plugin-api-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 27158 Nov 7 2019 maven-repository-metadata-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 148983 Nov 7 2019 maven-resolver-api-1.4.1.jar
-rw-r--r-- 1 khmarbaise staff 44143 Nov 7 2019 maven-resolver-connector-basic-1.4.1.jar
-rw-r--r-- 1 khmarbaise staff 180696 Nov 7 2019 maven-resolver-impl-1.4.1.jar
-rw-r--r-- 1 khmarbaise staff 66242 Nov 7 2019 maven-resolver-provider-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 36732 Nov 7 2019 maven-resolver-spi-1.4.1.jar
-rw-r--r-- 1 khmarbaise staff 31013 Nov 7 2019 maven-resolver-transport-wagon-1.4.1.jar
-rw-r--r-- 1 khmarbaise staff 167529 Nov 7 2019 maven-resolver-util-1.4.1.jar
-rw-r--r-- 1 khmarbaise staff 44047 Nov 7 2019 maven-settings-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 42090 Nov 7 2019 maven-settings-builder-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 166562 Nov 7 2019 maven-shared-utils-3.2.1.jar
-rw-r--r-- 1 khmarbaise staff 23815 Nov 7 2019 maven-slf4j-provider-3.6.3.jar
-rw-r--r-- 1 khmarbaise staff 379197 Nov 7 2019 org.eclipse.sisu.inject-0.3.4.jar
-rw-r--r-- 1 khmarbaise staff 11530 Nov 7 2019 org.eclipse.sisu.inject.license
-rw-r--r-- 1 khmarbaise staff 205323 Nov 7 2019 org.eclipse.sisu.plexus-0.3.4.jar
-rw-r--r-- 1 khmarbaise staff 11530 Nov 7 2019 org.eclipse.sisu.plexus.license
-rw-r--r-- 1 khmarbaise staff 13350 Nov 7 2019 plexus-cipher-1.7.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 plexus-cipher.license
-rw-r--r-- 1 khmarbaise staff 4225 Nov 7 2019 plexus-component-annotations-2.1.0.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 plexus-component-annotations.license
-rw-r--r-- 1 khmarbaise staff 85327 Nov 7 2019 plexus-interpolation-1.25.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 plexus-interpolation.license
-rw-r--r-- 1 khmarbaise staff 27703 Nov 7 2019 plexus-sec-dispatcher-1.4.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 plexus-sec-dispatcher.license
-rw-r--r-- 1 khmarbaise staff 261801 Nov 7 2019 plexus-utils-3.2.1.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 plexus-utils.license
-rw-r--r-- 1 khmarbaise staff 41424 Nov 7 2019 slf4j-api-1.7.29.jar
-rw-r--r-- 1 khmarbaise staff 1224 Nov 7 2019 slf4j-api.license
-rw-r--r-- 1 khmarbaise staff 11586 Nov 7 2019 wagon-file-3.3.4.jar
-rw-r--r-- 1 khmarbaise staff 2206349 Nov 7 2019 wagon-http-3.3.4-shaded.jar
-rw-r--r-- 1 khmarbaise staff 55776 Nov 7 2019 wagon-provider-api-3.3.4.jar
所有类似于 maven-core.. 等的文件都包含 Maven (3.6.3) 的版本号也是有问题的
-rw-r--r-- 1 khmarbaise staff 2591373 Nov 7 2019 guava-25.1-android.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 guava.license
-rw-r--r-- 1 khmarbaise staff 520662 Nov 7 2019 guice-4.2.1-no_aop.jar
-rw-r--r-- 1 khmarbaise staff 11560 Nov 7 2019 guice.license
您会看到，这与您拥有的给定输出特别不同，除了缺少其他工件的版本号之外，只有 file:/usr/share/maven/lib/guice-4.2.1-no_aop.jar。
这意味着问题是基于 Ubuntu Maven 的使用，并且不使用与 JDK 7 兼容的 Apache Maven，而重新打包的 Ubuntu 版本根本就不是。
最简单的解决方案是删除 Maven 的 ubuntu 包并安装原始的 Apache Maven https://maven.apache.org/download.cgi，然后使用 JDK 7 进行构建即可。 （下载并检查校验和等）
您也可以下载 Apache Maven 并根据您的发行版 (/usr/share/maven/lib/) 的文件检查文件的校验和，我敢打赌所有文件都不同。
该问题基于发行版的想法，即重新打包应用程序（例如 Maven）及其系统上的依赖项，这实际上意味着您有不同版本的依赖项，从而导致此类问题。