Invoking Maven from Java

On one of my work projects right now, I’m adding unit tests to a code generator. The easiest way to make sure the generated code works is to run mvn clean install. Of course, I want to do that from within the unit test and fail the test if the Maven run fails.

Fortunately, there’s Maven Invoker. Here’s how to use it:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
   private void invokeMavenInstall(File file) throws MavenInvocationException, CommandLineException {
        InvocationRequest request = new DefaultInvocationRequest();
        request.setPomFile(file);
        request.setBatchMode(true);
        request.setDebug(true);

        // this prevents M2_HOME from being added in MavenCommandLineBuilder.setShellEnvironment, which then fails to
        // start mvn with "Error: Could not find or load main class org.codehaus.plexus.classworlds.launcher.Launcher"
        request.setShellEnvironmentInherited(false);
        request.setGoals(Collections.singletonList("install"));

        Invoker invoker = new DefaultInvoker();
        invoker.setMavenHome(new File(System.getenv("M3_HOME")));
        invoker.setOutputHandler(new SystemOutHandler());
        invoker.setErrorHandler(new SystemOutHandler());
        invoker.setLogger(new PrintStreamLogger(System.out, InvokerLogger.DEBUG));
        InvocationResult result = invoker.execute(request);
        if (result.getExecutionException() != null) {
            throw result.getExecutionException();
        }
        assertEquals(0, result.getExitCode());
    }
}

The interesting bit here is the request.setShellEnvironmentInherited(false); line. Without it, the MavenCommandLineBuilder.setShellEnvironment method adds an environment variable M2_HOME to it, which prevents Maven from starting up.

Share

About Mathias

Software development engineer. Principal developer of DrJava. Recent Ph.D. graduate from the Department of Computer Science at Rice University.
This entry was posted in Uncategorized. Bookmark the permalink.

Leave a Reply