package com.company.model.entities;
 
import java.util.List;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
 
/**
 *
 * @author gus
 */
@XmlRootElement(name="Gestion")
@XmlAccessorType(XmlAccessType.FIELD)
public class Management {
    @XmlElement(name="Velocidad")
    private Double velocity;
    @XmlElement(name="Process")
    private List<Process> processes;
 
    public Management() {
 
    }
    public Management(Double velocity, List<Process> processes) {
    	this.velocity = velocity;
    	this.processes = processes;
    }
    public Double getVelocity() {
        return velocity;
    }
    public void setVelocity(Double velocity) {
        this.velocity = velocity;
    }
    public List<Process> getProcesses() {
        return processes;
    }
    public void setProcesses(List<Process> processes) {
        this.processes = processes;
    }
 
}

• @XmlRootElement: Indica que es el elemento padre de una jerarquía.
• @XmlElement: Indica que es un elemento XML (un tag).
• @XmlAccessorType, @XmlAccessType.FIELD: La primera se usa para establecer el tipo de acceso. La segunda indica que se accederá a los valores por propiedades (y no por getters/setters).

package com.company.model.entities;
 
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
 
/**
 *
 * @author gus
 */
@XmlAccessorType(XmlAccessType.FIELD)
public class Process {
    @XmlElement(name="Pid")
    private Short pid;
    @XmlElement(name="Name")
    private String name;
    @XmlElement(name="Quantum")
    private Short quantum; // ¿quántico?
    @XmlElement(name="Actividad")
    private Activity activity;
 
    public Process() {
 
    }
    public Process(Short pid, String name, Short quantum, Activity activity) {
        this.pid = pid;
        this.name = name;
        this.quantum = quantum;
        this.activity = activity;
    }
    public Short getPid() {
        return pid;
    }
    public void setPid(Short pid) {
        this.pid = pid;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Short getQuantum() {
        return quantum;
    }
    public void setQuantum(Short quantum) {
        this.quantum = quantum;
    }
    public Activity getActivity() {
        return activity;
    }
    public void setActivity(Activity activity) {
        this.activity = activity;
    }
 
}

package com.company.model.entities;
 
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
 
/**
 *
 * @author gus
 */
@XmlAccessorType(XmlAccessType.FIELD)
public class Activity {
    @XmlElement(name="Archivo_fuente")
    private String source;
    @XmlElement(name="Archivo_destino")
    private String target;
 
    public Activity() {
 
    }
    public Activity(String source, String target) {
        this.source = source;
        this.target = target;
    }
    public String getSource() {
        return source;
    }
    public void setSource(String source) {
        this.source = source;
    }
    public String getTarget() {
        return target;
    }
    public void setTarget(String target) {
        this.target = target;
    }
 
}

package com.company.model.jaxb;
import java.io.File;
 
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
 
 
 
public class MarshallerUtil<T> {
	private static JAXBContext jaxbContext;
	private final Class<T> clazz;
 
	public MarshallerUtil(Class<T> aClazz) throws JAXBException {
		this.clazz = aClazz;
		jaxbContext = JAXBContext.newInstance(clazz);
	}
 
	public void marshal(T entity, File output) throws JAXBException {
		Marshaller marshaller = jaxbContext.createMarshaller();
		marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
		marshaller.marshal(entity, output);
	}
 
	public T unmarshal(File input) throws JAXBException {
		Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
		return (T) unmarshaller.unmarshal(input);
	}
 
}

• T: Es el tipo de clase (entidad) que será trabajada por el Marshaller (transformador).
• marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);: Formatea el XML.
• marshaller.marshall(entity, file): Recibe la entidad a convertir a XML y el destino (ruta) en un objeto File.
• marshaller.unmarshal(file): Recibe la ruta del XML a convertir. Con el cast hacia T decimos que el XML se convierta a la entidad con la que se está trabajando (T = MarshallerUtil<CLASE_DE_ENTIDAD>).
  
  Por último, hagamos una prueba:
  
  Main
  
  

package com.company.main;
 
import com.company.model.entities.Activity;
import com.company.model.entities.Management;
import com.company.model.entities.Process;
import com.company.model.jaxb.MarshallerUtil;
import com.sun.istack.internal.logging.Logger;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.xml.bind.JAXBException;
 
 
public class Main {
 
	public static void main(String[] args) {
            Logger logger = Logger.getLogger(Main.class);
            try {
                /*Management management = new Management();
                List<Process> processes = new ArrayList<>();
                Collections.addAll(processes,
                        new Process(new Short("1"), "Proceso 1", new Short("1"),
                            new Activity("/home/gus/Documentos/origen.txt", "home/gus/Documentos")),
                        new Process(new Short("2"), "Proceso 2", new Short("4"),
                            new Activity("/home/gus/Documentos/origen.xml", "home/gus/Documentos")),
                        new Process(new Short("3"), "Proceso 3", new Short("3"),
                            new Activity("/home/gus/Documentos/origen.sh", "home/gus/Documentos"))
                );
                management.setVelocity(100.05d);
                management.setProcesses(processes);
                MarshallerUtil<Management> marshaller = new MarshallerUtil(Management.class);
                marshaller.marshal(management, new java.io.File("/home/gus/Documentos/prueba1.xml"));*/
 
                MarshallerUtil<Management> marshaller = new MarshallerUtil(Management.class);
                Management management = marshaller
                        .unmarshal(new java.io.File("/home/gus/Documentos/prueba.xml"));
                System.out.println(management.getVelocity());
                for(Process process : management.getProcesses()) {
                    System.out.println(process.getPid());
                    System.out.println(process.getName());
                    System.out.println(process.getQuantum());
                    System.out.println(process.getActivity().getSource());
                    System.out.println(process.getActivity().getTarget());
                    System.out.println();
                }
            } catch (JAXBException e) {
                logger.warning(e.getMessage());
            }
 
	}
 
}