exec-maven-plugin could not find or load main class but output runs fine on the command line

Question

I try to use the exec-maven-plugin to run a Java program.

I use the following pom snippet:

<plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.2.1</version>
             <configuration>
                    <executable>java</executable>
                        <arguments>
                         <argument>-Dmyproperty=myvalue</argument>
                            <argument>-cp</argument>
                            <argument>"/home/vogella/libs/*"</argument>
                            <argument>com.vogella.test.Main</argument>
                        </arguments>
    </configuration>


</plugin>

The class com.vogella.test.Main is contained in one of the jar files which are located in /home/vogella/libs/*. If I run the mvn -X clean install exec:exec command, I see the following error message:

[DEBUG] Executing command line: java -Dmyproperty=myvalue -cp "/home/vogella/libs/*" com.vogella.test.Main Error: Could not find or load main class com.vogella.test.Main

If I copy the command line (java -Dmyproperty=myvalue -cp "/home/vogella/libs/*" com.vogella.test.Main) in the shell from which I started the Maven build, then the Java program is executed correctly.

Any idea what is wrong with my Maven setup?

Answer 1

With CLI, the /home/vogella/libs/* expression is expanded by bash and resolves to the list of files. With Maven, the expression is directly executed and not expanded. so it remains "/home/vogella/libs/*" which is not a valid jar file. You'll probably have more success by using the antrun plugin and use the java Ant task in the script. Ant understands wildcards better than anything else.

Answer 2

You need to set the classpath through dependencies. With the commandline argument -cp you set the classpath explicitly but this does not work for the maven cp. This is constructed through dependencies.

<plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>1.2.1</version>
            <executions>
                <execution>
                    <phase>generate-sources</phase>
                    <goals>
                        <goal>java</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <includeProjectDependencies>false</includeProjectDependencies>
                <includePluginDependencies>true</includePluginDependencies>
                <mainClass>org.eclipse.emf.mwe2.launch.runtime.Mwe2Launcher</mainClass>
                <arguments>
                    <argument>${project.basedir}/src/my/mavenized/GenerateHeroLanguage.mwe2</argument>
                </arguments>
            </configuration>
            <dependencies>
                <dependency>
                    <groupId>org.eclipse.xtext</groupId>
                    <artifactId>org.eclipse.xtext.xtext</artifactId>
                    <version>2.5.0-SNAPSHOT</version>
                </dependency>
                <dependency>
                    <groupId>org.eclipse.xtext</groupId>
                    <artifactId>org.eclipse.xtext.xbase</artifactId>
                    <version>2.5.0-SNAPSHOT</version>
                </dependency>
            </dependencies>
        </plugin>