Replacing Default Configuration Iterpolator with Custom

Question

I have been trying to register a custom configuration interpolator in the commons configuration that would take care of some fallback values by default.

Here is the code for interpolator.

   public class FallbackConfigurationInterpolator extends ConfigurationInterpolator {

    Pattern p = Pattern.compile("\\d+$");

    public FallbackConfigurationInterpolator() {
        super();
    }

    @Override
    public String lookup(String var) {
        String value = super.lookup(var);
        if (StringUtils.startsWith(value, "${") && endsWithDigits(var)) {
            value = super.lookup(valueWithRemovedDigits(var));
        }
        return value;
    }

    private String valueWithRemovedDigits(String var) {
        return var.replace("\\d+$", StringUtils.EMPTY);
    }

    private boolean endsWithDigits(String var) {
        return p.matcher(var).matches();
    }



}

Here is how my configuration builder looks like

 public class CustomCommonsConfigurationBuilder extends DefaultConfigurationBuilder {

        public CustomCommonsConfigurationBuilder() {
            super();
        }

        public CustomCommonsConfigurationBuilder(String fileName) throws ConfigurationException {
            super(fileName);
        }

        public CustomCommonsConfigurationBuilder(File file) {
            super(file);
        }

        public CustomCommonsConfigurationBuilder(URL url) throws ConfigurationException {
            super(url);
        }

        @Override
        protected ConfigurationInterpolator createInterpolator() {
            FallbackConfigurationInterpolator interpol = new FallbackConfigurationInterpolator();
            interpol.setDefaultLookup(new StrLookup() {
                @Override
                public String lookup(String var) {
                    Object prop = resolveContainerStore(var);
                    return (prop != null) ? prop.toString() : null;
                }
            });
            return interpol;
        }
    }

Here is how i am instantiating my configuration builder.

@Before
    public void setup() throws ConfigurationException {
        System.setProperty("environment", "local");
        config = (AbstractConfiguration) new CustomCommonsConfigurationBuilder("commons-configuration.xml")
            .getConfiguration();
        config.getSubstitutor().setEnableSubstitutionInVariables(true);
    }

For some reason the lookup method in my custom interpolator is never called. Can someone please help if you've had success registering custom interpolators?

Thanks in Advance.

Replacing Default Configuration Iterpolator with Custom

0 Answers0