maven - Automatically incrementing a build number in a Java project

Question

I'm using a versioning system that is represented by a.b.build where a is the overall version (will be 0 for prototype, alpha and beta versions, 1 for major release), b is the milestone version (along the lines of representing the proto, alpha, beta stages) and build represents literally the amount of times the project has been compiled.

At the moment, I have the app read from a text file, increment the number, and save to a text file when the app is run with a debug flag set.

I'm looking for a more "correct" way to do this using Java and Netbeans. Is there some way I can inject a build numberer into the build process somewhere? preferably saving the number into a source file that is shipped with the project - instead of relying on the existence of a nearby file.

Answer 1

There are a couple of popular Maven plugins that accomplish this feat:

• Maven Release Plugin
• Build Number Maven Plugin

The Maven Release Plugin from the Apache Maven Project is a bit overkill for simply updating the version number. Therefore use the latter plugin to create a version number (in the form of MAJOR.MINOR.BUILD; e.g., 3.1.4 where 4 is auto-incremented) as follows:

1. Open the project's pom.xml file.
2. Include the plugin within the build section (after the dependencies section):

  <scm>
    <connection>scm:svn:http://127.0.0.1/dummy</connection>
    <developerConnection>scm:svn:https://127.0.0.1/dummy</developerConnection>
    <tag>HEAD</tag>
    <url>http://127.0.0.1/dummy</url>
  </scm>
  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>buildnumber-maven-plugin</artifactId>
        <version>1.4</version>
        <executions>
          <execution>
            <id>buildnumber</id>
            <phase>validate</phase>
            <goals>
              <goal>create</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <format>{0,number}</format>
          <items>
            <item>buildNumber</item>
          </items>                    
          <doCheck>false</doCheck>
          <doUpdate>false</doUpdate>
          <revisionOnScmFailure>unknownbuild</revisionOnScmFailure>   
        </configuration>
      </plugin>    
    </plugins>
    <finalName>${project.artifactId}-${project.version}.${buildNumber}</finalName>
  </build>

3. Ensure that the pom.xml defines the major and minor version in the version element near the top of the file. For example:

<version>3.1</version>

4. Save the pom.xml file.
5. Rebuild the project.

The version number should increase.

---

The plugin requires a configured source code management repository (<scm>) element. If you don't care about the repository check-in number use a dummy scm instead. This can be used to include the revision number from the repository, which is an exercise for the reader.