From Maven, how do I run a class that lives under

问题:

I have inherited a codebase :)

Under src/test/java/ there's a file that I need to run (I need to run its public static void main(String[] args), not a @Test method within it).

The closest I have got is:

mvn -e exec:java -Dexec.mainClass="com.me.packagex.RunFile" -Dexec.classpathScope="test"

but that then fails, and it appears to be because RunFile wants to use classes that exist under src/main/java/com/me/packagex/ (notice, /main/, not /test/). The files under there are in the same package as RunFile, i.e. 'package com.me.packagex;'.

If I remove the -Dexec.classpathScope="test" then it can't find RunFile at all. It's as if I need to give it two scopes, but it doesn't accept "test,compile".

The person I've inherited this from (dearly departed) used to run it from Eclipse. I need a way to run it from the command-line.

I hope this is clearly explained.

tyvm,

---

This is promising. Pascal, I've tried your example and that doesn't work for me.

Although now I look at it - it's not finding Demo, rather than not finding Dog.

Apache Maven 2.2.1 (rdebian-1)
Java version: 1.6.0_18
Java home: /usr/lib/jvm/java-6-openjdk/jre
Default locale: en_GB, platform encoding: UTF-8
OS name: "linux" version: "2.6.32-25-generic" arch: "i386" Family: "unix"

$ mvn -e exec:java -Dexec.mainClass="com.stackoverflow.Demo" -Dexec.classpathScope="test"

[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] An exception occured while executing the Java class. com.stackoverflow.Demo

[INFO] ------------------------------------------------------------------------
[INFO] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: An exception occured while executing the Java class. com.stackoverflow.Demo
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:719)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:569)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:539)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
        at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
        at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
        at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
        at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: org.apache.maven.plugin.MojoExecutionException: An exception occured while executing the Java class. com.stackoverflow.Demo
        at org.codehaus.mojo.exec.ExecJavaMojo.execute(ExecJavaMojo.java:346)
        at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
        ... 17 more
Caused by: java.lang.ClassNotFoundException: com.stackoverflow.Demo
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
        at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:284)
        at java.lang.Thread.run(Thread.java:619)

回答1:

(...) I hope this is clearly explained.

Not bad but I can't reproduce. I created a project:

$ mvn archetype:generate -DgroupId=com.stackoverflow \
                         -DartifactId=Q4060613 \
                         -Dversion=1.0-SNAPSHOT \
                         -DarchetypeArtifactId=maven-archetype-quickstart 

Then cded into it and created a Dog class (under src/main/java):

$ cd Q4060613
$ cat > src/main/java/com/stackoverflow/Dog.java
package com.stackoverflow;

public class Dog {
    public String bark() {
        return "woof!";
    }
}

and created a Demo class (under src/test/java):

$ cat > src/test/java/com/stackoverflow/Demo.java 
package com.stackoverflow;

public class Demo {
    public static void main(String[] args) {
        System.out.println(new Dog().bark());
    }
}

After compiling the source code, running the command you provided works as expected:

$ mvn test
...
$ mvn exec:java -Dexec.mainClass="com.stackoverflow.Demo" -Dexec.classpathScope="test"
[INFO] Scanning for projects...
...
[INFO] --- exec-maven-plugin:1.2:java (default-cli) @ Q4060613 ---
woof!
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
...

Something else must be wrong.

回答2:

Include following lines in pom.xml in exec-maven-plugin plugin. <classpathScope>test</classpathScope>

plugin section in POM looks something like this

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>exec-maven-plugin</artifactId>
    <executions>
        <execution>
            <id>my-execution</id>
            <phase>test</phase>
            <goals>
                <goal>java</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <mainClass>com.example.MainClass</mainClass>
            <classpathScope>test</classpathScope>
    </configuration>
</plugin>

Note : com.example.MainClass is the class containing main method.

回答3:

I faced the same problem and figured it out.

Shortly speaking, the class must be compiled before exec:java goal. (It surely works without test-compile phase if the class is already compiled by other user action. Note that Pascal Thivent, in his answer, invoked mvn test before exec:java.)

$ mvn -Dexec.mainClass=... -Dexec.classpathScope=test test-compile exec:java

You can prove it for yourself if you want to see the ClassNotFoundException again.

$ mvn -Dexec.mainClass=... -Dexec.classpathScope=test clean exec:java

回答4:

Ok, spurred on by it working for everyone else I dug a little harder. The code wasn't reporting its problems very well and I was misreading the stacktrace.

It does:

FileInputStream is = new FileInputStream("lib/other-thing.jar");

which was failing. I symlinked trunk/src/main/assembly/lib/ into trunk/ and now it works. There might be a neater way to fix that then the symlink, though.

Thank you chaps.