<h:form>
            <h:commandButton
                action="#{mainPageBB.goToLink}" value="#{msgs.clickhere}"/>
        </h:form>

@Named("mainPageBB")
@RequestScoped
public class MainPageBB {

    @EJB
    private ILinkManagerEJB linkManagerEJB;


    public String goToLink() {
        String link = linkManagerEJB.retrieveLink();
        if(link != null) {
                    System.out.println(link);
            return link.trim() + "?faces-redirect=true";
        }
        return null;
    }

public String goToRandomLink() {
        String link = linkManagerEJB.retrieveRandomLink();
        if(link != null) {
            ExternalContext externalContext = FacesContext.getCurrentInstance().getExternalContext();
            try {
                externalContext.redirect(link.trim());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

ExternalContext externalContext = FacesContext.getCurrentInstance().getExternalContext();
externalContext.redirect(link.trim());