Question

I only need to use this class org.apache.commons.io.FileUtils, and yet I’m downloading all commons Classes which I actually don’t need, is there a way to say to maven download just FileUtils class? Not whole commons like from dependency below

<dependency>
   <groupId>commons-io</groupId>
   <artifactId>commons-io</artifactId>
   <version>1.4</version>
</dependency>

Answer 1

is there a way to say to maven download just FileUtils class?

No. But depending on your exact use case, you could maybe use the Maven Shade Plugin to create an uber-jar and filter the content of the included dependencies:

Selecting Contents for Uber JAR

…

For fine-grained control of which
classes from the selected dependencies
are included, artifact filters can be
used:

<project>
  ... 
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>1.3.3</version>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <filters>
                <filter>
                  <artifact>junit:junit</artifact>
                  <includes>
                    <include>junit/framework/**</include>
                    <include>org/junit/**</include>
                  </includes>
                  <excludes>
                    <exclude>org/junit/experimental/**</exclude>
                    <exclude>org/junit/runners/**</exclude>
                  </excludes>
                </filter>
                <filter>
                  <artifact>*:*</artifact>
                  <excludes>
                    <exclude>META-INF/*.SF</exclude>
                    <exclude>META-INF/*.DSA</exclude>
                    <exclude>META-INF/*.RSA</exclude>
                  </excludes>
                </filter>
              </filters>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  ...
</project>

Here, Ant-like patterns are used to
specify that from the dependency
junit:junit only certain
classes/resources should be included
in the uber JAR. The second filter
demonstrates the use of wildcards for
the artifact identity which was
introduced in plugin version 1.3. It
excludes all signature related files
from every artifact, regardless of its
group or artifact id.

But note that FileUtils depends on other classes:

import org.apache.commons.io.filefilter.DirectoryFileFilter;
import org.apache.commons.io.filefilter.FalseFileFilter;
import org.apache.commons.io.filefilter.FileFilterUtils;
import org.apache.commons.io.filefilter.IOFileFilter;
import org.apache.commons.io.filefilter.SuffixFileFilter; // depends on org.apache.commons.io.IOCase
import org.apache.commons.io.filefilter.TrueFileFilter;
import org.apache.commons.io.output.NullOutputStream;

That you’ll obviously need to include too.