The Maven JAR Plugin is used to package your project artifacts into jar files.

Goals:

• jar:jar create a jar file for your project classes inclusive resources.
• jar:test-jar create a jar file for your project test classes .

Build a JAR file:

Add the following into your Maven project POM:

<project>
  <modelVersion>4.0.0</modelVersion>
  
  <groupId>com.mycompany.project</groupId>
  <artifactId>core</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>
</project>

Run the following Maven command:

mvn package

Output:

[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ HelloWorld ---
[INFO] Building jar: C:\projects\HelloWorldApplication\target\HelloWorld-1.0-SNAPSHOT.jar

Customize the Manifest file: The following configuration will modify the default manifest file included in your build Jar.

<build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <version>3.2.0</version>
        <configuration>
          <archive>
            <index>true</index>
            <manifest>
              <addClasspath>true</addClasspath>
            </manifest>
            <manifestEntries>
              <mode>development</mode>
              <url>${project.url}</url>
              <key>value</key>
            </manifestEntries>
          </archive>
        </configuration>
        ...
      </plugin>
    </plugins>
  </build>

Include/Exclude content from Jar: The following configuration will exclude all txt files in the build artifact.

<build>
  <plugins>
    ...
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-jar-plugin</artifactId>
      <version>3.2.0</version>
      <configuration>
        <excludes>
          <exclude>**/*.txt/*</exclude>
        </excludes>
      </configuration>
    </plugin>
    ...
  </plugins>
</build>