Apache Maven Access Maven informations in code Keeping a properties file in sync using maven's property filtering mecanism

Example

As this documentation explains,

Sometimes a resource file will need to contain a value that can only be supplied at build time. To accomplish this in Maven, put a reference to the property that will contain the value into your resource file using the syntax ${<property name>}. The property can be one of the values defined in your pom.xml, a value defined in the user's settings.xml, a property defined in an external properties file, or a system property.

As an example, let's create a simple info.txt in src/main/resources containing the pom version and the build time.

1. create a src/main/resources/info.txt with the following content:

   version=${pom.version} build.date=${timestamp}

2. ask Maven to expand the properties by setting filtering to true:

    <build>
        <resources>
            <resource>
               <directory>src/main/resources</directory>
               <filtering>true</filtering>
            </resource>
        </resources>
    </build>
   

3. with that, the version will be updated, but unfortunately a bug within Maven prevents the ${maven.build.timestamp} property from getting passed to the resource filtering mechanism (more info here). So, let's create a timestamp property as a workaround ! Add the following to the pom's properties:

    <properties>
        <timestamp>${maven.build.timestamp}</timestamp>
        <maven.build.timestamp.format>yyyy-MM-dd'T'HH:mm</maven.build.timestamp.format>  
    </properties>
   

4. run maven, you should find a info.txt in target/classes with a content like:

    version=0.3.2
    build.date=2017-04-20T13:56