build - Maven - how can I add an arbitrary classpath entry to a jar?

Question

I have an unusual situation where I need to add an arbitrary classpath entry (that points to a jar file) into the manifest of an executable jar. (This is for a Swing desktop application.)

The maven-jar-plugin generates the "Class-Path" entry for the jar manifest using the maven dependencies, and there doesn't appear to be any way of adding arbitrary entries.

I also looked at hard-coding the arbitrary classpath entry into the batch file that starts the application, using the "-classpath" parameter, but I can't figure out how to get Maven to filter the classpath into a batch file.

Answer 1

I found that there is an easy solution for this problem. You can add a <Class-Path> element to <manifestEntries> element, and set <addClassPath>true</addClassPath> to <manifest> element. So value of <Class-Path> element is added to class-path automatically. Example:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-jar-plugin</artifactId>
  <configuration>
    <archive>
      <manifest>
        <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
        <addClasspath>true</addClasspath>
        <mainClass>your.main.Class</mainClass>
      </manifest>
      <manifestEntries>
        <Class-Path>../conf/</Class-Path>
      </manifestEntries>
    </archive>
  </configuration>
</plugin>