How to place the output jar into another folder with maven?

Another way would be maven-resources-plugin (find the current version here):

<plugin>
   <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-resources-plugin</artifactId>
    <version>3.0.2</version>
    <executions>
        <execution>
            <id>copy-files-on-build</id>
            <phase>package</phase>
            <goals>
                <goal>copy-resources</goal>
            </goals>
            <configuration>
                <outputDirectory>${basedir}/[TO-DIR]</outputDirectory>
                <resources>
                    <resource>
                        <directory>[FROM-DIR]</directory>
                        <!--<include>*.[MIME-TYPE]</include>-->
                        <filtering>false</filtering>
                    </resource>
                </resources>
            </configuration>
        </execution>
    </executions>
</plugin>

You can use the outputDirectory parameter of the maven-jar-plugin for this purpose:

<project>
  ...
  <build>
    <plugins>
      ...
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <version>2.3.1</version>
        <configuration>
          <outputDirectory>../libs</outputDirectory>
        </configuration>
      </plugin>
      ...
    </plugins>
  </build>
  ...
</project>

But as cdegroot wrote, you should probably better not fight the maven way.

If you want to copy the artifact into a directory outside your project, solutions might be:

• maven-jar-plugin and configure outputDirectory
• maven-antrun-plugin and copy task
• copy-maven-plugin by Evgeny Goldin

Example for the copy-maven-plugin is:

<plugin>
    <groupId>com.github.goldin</groupId>
    <artifactId>copy-maven-plugin</artifactId>
    <version>0.2.5</version>
    <executions>
        <execution>
            <id>deploy-to-local-directory</id>
            <phase>install</phase>
            <goals>
                <goal>copy</goal>
            </goals>
            <configuration>
                <skipIdentical>false</skipIdentical>
                <failIfNotFound>false</failIfNotFound>
                <resources>
                    <resource>
                        <description>Copy artifact to another directory</description>
                        <targetPath>/your/local/path</targetPath>
                        <directory>${project.build.directory}</directory>
                        <includes>
                            <include>*.jar</include>
                        </includes>
                    </resource>
                </resources>
            </configuration>
        </execution>
    </executions>
</plugin>