Custom Types

It is possible to provide license matchers or license families of your own by implementing one of the Rat interfaces and providing the implementation as an Ant type. This example will show how to use a custom license matcher.

To be suitable as an Ant type your class must provide a public no-arg constructor (or no constructor at all). If you want to support configuration of your instance via XML attributes or nested elements your type must provide methods that follow Ant's method naming conventions. For details see the Writing Your Own Task section in Ant's manual.

For this example let us assume you want to match a license that looks like

   * Yet Another Software License, 1.0
   * Lots of text, specifying the users rights, and whatever ...

and to make things a bit more interesting the version number shall be configurable as an attribute on your type.

An implementation of this matcher could look like

package org.example;

import org.apache.rat.analysis.IHeaderMatcher;
import org.apache.rat.analysis.RatHeaderAnalysisException;
import org.apache.rat.api.Document;
import org.apache.rat.api.MetaData;
import org.apache.rat.api.MetaData.Datum;

/** Just a POJO with no constructor at all */
public class YASLMatcher implements IHeaderMatcher {
    private final String MATCH = "Yet Another Software License, ";
    private final String FAMILY = "YASL";
    private final String ONE = "1.0";
    private String matchWithVersion = MATCH + ONE;
    private String familyWithVersion = FAMILY + ONE;

    /** becomes the version attribute */
    public void setVersion(String v) {
       matchWithVersion = MATCH + v;
       familyWithVersion = FAMILY + v;

    public void reset() { }

    /** trivial implementation that looks for a fixed string */
    public boolean match(Document subject, String line)
           throws RatHeaderAnalysisException {
        if (line.indexOf(matchWithVersion) >= 0) {
            // this is what matchers are supposed to do when they find a
            // match, even though it is not documented very well
            subject.getMetaData().set(new Datum(MetaData.RAT_URL_LICENSE_FAMILY_CATEGORY,
            return true;
        return false;

Actually it would be easier to use Rat's SimplePatternBasedLicense implementation or the built-in substringMatcher, but this is just an example.

In order to use your matcher it has to be defined as an Ant type. You do so by either using typedef or componentdef. If you are using Ant 1.8.x you should use componentdef.

In the most simple case this means

<componentdef name="yasl"

Since you will be using classes from Rat's core in both the Report task and your implementation you must ensure they get loaded via the same classloader. If you are using the -lib command line switch Rat's core will be part of Ant's core classloader and you don't need to reference it in the typedef for yasl at all.

If you define the Rat Antlib via a taskdef task with a nested classpath then you just use the same classpath when defining your custom matcher as well and set loaderRef to the same name. I.e.

<path id="rat-classpath">
    <pathelement location="YOUR-PATH-TO/apache-rat-${version}.jar"/>
    <pathelement location="YOUR-PATH-TO/yasl-matcher.jar"/>
<componentdef name="yasl"

With a definition like this you can use your matcher as in

    <fileset dir="src"/>

to detect Version 1.0 or

    <fileset dir="src"/>
    <yasl version="2.0"/>

for 2.0.