7

mvn -e package我在 Ubuntu 12.04 中收到此错误：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.0.2:compile (default-compile) on project HadoopSkeleton: Compilation failure: Compilation failure:
[ERROR] /home/jesvin/dev/hadoop/HadoopMahoutSkeleton-master/src/main/java/HadoopSkeleton/App.java:[22,8] error: generics are not supported in -source 1.3
[ERROR] 
[ERROR] (use -source 5 or higher to enable generics)
[ERROR] /home/jesvin/dev/hadoop/HadoopMahoutSkeleton-master/src/main/java/HadoopSkeleton/App.java:[53,28] error: for-each loops are not supported in -source 1.3
[ERROR] -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.0.2:compile (default-compile) on project HadoopSkeleton: Compilation failure
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:213)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    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:601)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.CompilationFailureException: Compilation failure
    at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:516)
    at org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:114)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    ... 19 more
[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/MojoFailureException

所以我猜Maven被迫针对旧版本的Java进行编译。但它为什么这样做呢？我只想要一个构建 Mahout jar 的 Maven 配置。

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-core</artifactId>
        <version>1.0.4</version>
        <!-- or whatever version -->
    </dependency>
    <dependency>
        <groupId>org.apache.mahout</groupId>
        <artifactId>mahout-core</artifactId>
        <version>0.7</version>
    </dependency>
</dependencies>

我正在尝试通过https://github.com/yeahiii/HadoopMahoutSkeleton/blob/master/pom.xml构建

java version "1.7.0_21"
Java(TM) SE Runtime Environment (build 1.7.0_21-b11)
Java HotSpot(TM) Server VM (build 23.21-b01, mixed mode)
4

2 回答 2

14

使用 Maven 编译器插件

<plugins>
     <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.1</version>
          <configuration>
              <source>1.7</source>
              <target>1.7</target>
          </configuration>
      </plugin>
</plugins>
于 2013-05-21T05:57:29.643 回答
1

This answer to a similar qestion可能会回答您最初的问题，即为什么。

引用该帖子：

配置 Maven 编译器插件将解决该问题。事实证明，问题是由 Ubuntu 存储库中的 Maven3 包引起的。另一种解决方法是从使用更新的编译器插件的 Apache 网站下载 Maven 3。

我想知道为什么当文档声明默认 Java 源是 1.5 时会发生这种情况。要查看 mvn 用于您的编译器插件的内容，请使用：

mvn help:有效的pom

即使我使用的是 Ubuntu 软件包中的 Maven 3.0.4，我的 Maven 编译器插件也是 2.0.2。当我使用来自 Apache 的 Maven 3.0.4 运行相同的命令时，我有一个插件版本 2.3.2，它按预期默认为 Java 1.5。

于 2015-01-20T03:32:38.717 回答