how to pass value from build.xml file to java class?

Question

i want to pass the value from build.xml file to java class at run time. We know that we can pass value from command line with ant to the build.xml file. But how to pass this value from build file to java file. We can done it with property file but how?

maybe this helps: http://stackoverflow.com/questions/3730880/use-ant-for-running-program-with-command-line-arguments — raven, Oct 19 '11 at 06:48
You need to be more specific. Do you want Ant to modify your source code (a .java file), or do you want to access a value (of a property?) generated by Ant while your program runs? — MaDa, Oct 19 '11 at 08:03

score 2 · Answer 1 · answered Oct 19 '11 at 06:48

Use the PropertyFile task to manipulate a properties file from ant.
Copy that file to your classpath
Use getClass().getClassLoader().getResourceAsStream() to open an input stream to the properties file.
Pass that InputStream to Properties.load() to load the properties in your app.

Sasha Bond · Answer 2 · 2021-08-27T15:02:14.630

assume you want to read <property name="version" value="123"/> from build.xml, here is plain xml read/parse approach

@Test
public void test_read_build_xml() {
    String buildVersion = null;
    try {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        factory.setNamespaceAware(true);
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document doc = builder.parse(new File("build.xml"));
        XPathFactory xPathfactory = XPathFactory.newInstance();
        XPath xpath = xPathfactory.newXPath();
        XPathExpression expr = xpath.compile("/project/property[@name='version']/@value");
        NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
        buildVersion = nodes.item(0).getNodeValue();
    } catch (Exception ex) {
        logger.error("cannot read build version");
    }
    logger.info("buildVersion: " + buildVersion);
    assertNotNull(buildVersion);
}

you can also user Project, ProjectHelper - see How to parse and interpret ant's build.xml

if you want to modify source code from ant, see Is it possible to modify source code with ant?

how to pass value from build.xml file to java class?

2 Answers2