Ant: How to execute Ant from Java

Question

I'm trying execute Ant target from Java for searching directories by criteria. If run searchDirectories from console, result is OK, if from Java class, directories not found.

File buildFile = new File("build.xml");

Project p = new Project();
p.setUserProperty("ant.file", buildFile.getAbsolutePath());
p.init();
ProjectHelper helper = ProjectHelper.getProjectHelper();
DefaultLogger consoleLogger = new DefaultLogger();
consoleLogger.setErrorPrintStream(System.err);
consoleLogger.setOutputPrintStream(System.out);
consoleLogger.setMessageOutputLevel(Project.MSG_INFO);
p.addBuildListener(consoleLogger);
p.addReference("ant.projectHelper", helper);
helper.parse(p, buildFile);

try {
    p.fireBuildStarted();
    p.fireSubBuildStarted();
    p.executeTarget("searchDirectories");
} catch (IOException e) {
    p.fireBuildFinished(e);
}

EDIT: If I call Ant from directory where contains build.xml, directories will be found. Otherwise when ant is executed via this line the result is incorrect.

ant -buildfile D:\Projects\antproj searchDirectories

I can't understand what is the problem?

What about Runtime#exec(String)? You can execute the same command you use in your shell. — beatngu13

beatngu13 beatngu13 · Accepted Answer · 2016-10-22T22:26:47

You can execute Ant from Java and print the output to System.out as follows (note that -buildfile is the same as -file or -f):

ProcessBuilder builder = new ProcessBuilder("ant", "-f", "/path/to/build.xml", "searchDirectories");
Process process = builder.start();

try (BufferedReader out = new BufferedReader(new InputStreamReader(process.getInputStream()))) {
    out.lines().collect(Collectors.toList()).forEach(System.out::println);
}

If your searchDirectories task produces wrong results, maybe the corresponding <target> contains a bug.

Ant: How to execute Ant from Java

1 Answers