public class Log4jInit extends HttpServlet{

private static final long serialVersionUID = 1L;

public void init(){

    String file = getInitParameter(Constantes.LOG4JINIT);

    try{
        if(file != null){
            Properties props = new Properties();
            props.load(new FileInputStream(file));
            PropertyConfigurator.configure(props);
        }

    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

<servlet>
    <servlet-name>log4j-init</servlet-name>
    <servlet-class>es.elcorteingles.n005.utils.Log4jInit</servlet-class>
    <init-param>
        <param-name>log4j-init-file</param-name>
        <param-value>classpath:log4j.properties</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

<resource>
        <directory>src/main/resource</directory>
        <targetPath>${project.build.directory}</targetPath>
        <filtering>true</filtering>
         <includes>
          <include>**/*.properties</include>
        </includes>
      </resource>