如何在maven3中修复关于javac参数`--add-exports`的`编译失败'

Question

我的代码包含sun.misc.SharedSecrets类和sun.nio.ch.Interruptible类，我希望它们在java模块化maven中工作。

代码在Java 11，maven 3.6.1中运行， maven-compiler-plugin版本为3.8.1。

maven-compiler-plugin的配置是：

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.1</version>
    <configuration>
        <source>11</source>
        <target>11</target>
        <encoding>UTF-8</encoding>
        <showWarnings>true</showWarnings>
        <showDeprecation>true</showDeprecation>
        <compilerArgs>
            <arg>--add-exports java.base/jdk.internal.misc=cn.piumnl.learning.java.interrupt</arg>
            <arg>--add-exports java.base/sun.nio.ch=cn.piumnl.learning.java.interrupt</arg>
        </compilerArgs>
    </configuration>
</plugin>

并运行maven package -X ，输出错误信息：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project concurrent: Fatal error compiling: 错误: 无效的标记: --add-exports java.base/jdk.internal.misc=cn.piumnl.learning.java.interrupt -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project concurrent: Fatal error compiling

我猜因为maven编译时的javac版本太低了。 所以我更新了maven-compiler-plugin的配置：

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.1</version>
    <configuration>
        <source>11</source>
        <target>11</target>
        <encoding>UTF-8</encoding>
        <showWarnings>true</showWarnings>
        <showDeprecation>true</showDeprecation>

        <!-- update -->
        <verbose>false</verbose>
        <fork>true</fork>
        <executable>C:\Program Files\Java\jdk-11\bin\javac</executable>
        <compilerVersion>11</compilerVersion>
        <!-- update -->

        <compilerArgs>
            <arg>--add-exports java.base/jdk.internal.misc=cn.piumnl.learning.java.interrupt</arg>
            <arg>--add-exports java.base/sun.nio.ch=cn.piumnl.learning.java.interrupt</arg>
        </compilerArgs>
    </configuration>
</plugin>

并运行maven package -X ，输出错误信息：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project concurrent: Compilation failure -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project concurrent: Compilation failure
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    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:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    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:566)
    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)
    at org.codehaus.classworlds.Launcher.main (Launcher.java:47)
Caused by: org.apache.maven.plugin.compiler.CompilationFailureException: Compilation failure
    at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute (AbstractCompilerMojo.java:1224)
    at org.apache.maven.plugin.compiler.CompilerMojo.execute (CompilerMojo.java:187)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    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:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    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:566)
    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)
    at org.codehaus.classworlds.Launcher.main (Launcher.java:47)
[ERROR] 
[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

这次maven没有提供更多有用的信息。 maven-compiler-plugin不支持--add-exports吗？

或者，当maven编译时，还有其他方法可以获取参数--add-exports to javac吗？

Answer 1

在这个问题上，我犯了三个错误。

1. 在JDK8中， SharedSecrets全名是sun.misc.SharedSecrets ，但在JDK9中，后来是jdk.internal.misc.SharedSecrets 。
2. 另一个是maven-compiler-plugin ， <compilerArgs></compilerArgs>只支持一个参数。 必须更改<compilerArgs><arg></arg></compilerArgs> 。
3. 编译参数应该是--add-exports=java.base/jdk.internal.misc=<you moudle>而不是--add-exports java.base/jdk.internal.misc=<you moudle>

最后，maven的配置应该是这样的：

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.1</version>
    <configuration>
        <source>11</source>
        <target>11</target>
        <encoding>UTF-8</encoding>
        <showWarnings>true</showWarnings>
        <showDeprecation>true</showDeprecation>

        <!-- update -->
        <verbose>false</verbose>
        <fork>true</fork>
        <executable>C:\Program Files\Java\jdk-11\bin\javac</executable>
        <compilerVersion>11</compilerVersion>
        <!-- update -->

        <compilerArgs>
            <arg>--add-exports=java.base/jdk.internal.misc=cn.piumnl.learning.java.interrupt</arg>
            <arg>--add-exports=java.base/sun.nio.ch=cn.piumnl.learning.java.interrupt</arg>
        </compilerArgs>
    </configuration>
</plugin>