AutoComplete Primefaces + BD Como fazer?

<p:dialog header="Nova Visita" widgetVar="dialogo2" draggable="true"
	width="790" height="400" resizable="false" modal="true"
	closable="false" position="center">

	<h:form id="formNovaVisita" enctype="multipart/form-data">
		<h:panelGrid columns="2" id="painel2">

			<p:outputLabel for="code2" value="Cpf/RG:" />

 <!-- AUTOCOMPLETE--> 
			<p:autoComplete id="code2" value="#{autoCompleteView.visitante}"
				completeMethod="#{autoCompleteView.completeVisita}" size="16"
				var="dv" itemLabel="#{dv.code}" itemValue="#"
				converter="visitanteConverter" forceSelection="true"
				requiredMessage="O campo CPF/RG é obrigatorio"
				validatorMessage="O numero minimo de caracteres permitido é de 5 caracteres">
				<f:validateLength maximum="15" minimum="5" />
				<f:facet name="itemtip">
					<h:panelGrid columns="2" cellpadding="5">
						<f:facet name="header">
							<h:graphicImage width="50"
								url="http://localhost:8080/uploads/#{v.code}.png"
								style="margin-left:50px" />
						</f:facet>

						<h:outputText value="Nome:" />
						<h:outputText value="#{dv.nome}" />

						<h:outputText value="Empresa:" />
						<h:outputText value="#{dv.empresa}" />

					</h:panelGrid>
				</f:facet>
			</p:autoComplete>

			<p:outputLabel for="nome2" value="Nome:" />
			<p:inputText id="nome2" maxlength="40" size="40" type="text"
				required="true" requiredMessage="O campo Nome é obrigatorio"
				value="#{visitanteBean.visitante.nome}" forceSelection="true"/>


			<p:outputLabel for="empresa2" value="Nome da empresa:" />
			<p:autoComplete id="empresa2" maxlength="45" size="40"
				required="true"
				requiredMessage="O campo Nome da Empresa é obrigatorio"
				value="#{visitanteBean.visitante.empresa}" forceSelection="true">

			</p:autoComplete>

			<p:outputLabel for="obs" value="Observações da Visita:" />
			<p:inputTextarea id="obs" maxlength="200" size="60"
				value="#{visitanteBean.visitante.obs}" />

			<p:outputLabel for="subir" value="Foto:" />
			<h:panelGrid columns="2" id="painelFoto">
				<h:graphicImage width="150"
					url="http://localhost:8080/uploads/#{dv.code}.png" />
				<p:fileUpload id="subir" label="Procurar" mode="advanced"
					fileUploadListener="#{visitanteBean.subir}"
					invalidFileMessage="Tipo de Arquivo incorreto"
					invalidSizeMessage="Foto muito grande" update=":msg" auto="true"
					allowTypes="/(\\.|\\/)(gif|jpe?g|png)$/" />
			</h:panelGrid>
		</h:panelGrid>

		<h:panelGrid columns="3">
			<p:commandButton value="Salvar"
				actionListener="#{visitanteBean.salvar}"
				update=":formLista:table :msg :formNovaVisita:painel2" />
			<p:commandButton value="Limpar" ajax="true" immediate="true"
				type="reset" />
			<p:commandButton value="Fechar" oncomplete="PF('dialogo2').hide();" />
		</h:panelGrid>
	</h:form>
</p:dialog>

@FacesConverter("visitanteConverter")
public class VisitanteConverter implements Converter {

public Object getAsObject(FacesContext fc, UIComponent uic, String value) {
    if(value != null && value.trim().length() > 0) {
        try {
        	VisitaService service = (VisitaService) fc.getExternalContext().getApplicationMap().get("visitaService");
            return service.getVisitas().get(Integer.parseInt(value));
        } catch(NumberFormatException e) {
            throw new ConverterException(new FacesMessage(FacesMessage.SEVERITY_ERROR, "Erro de conversão", "Visitante não é valido."));
        }
    }
    else {
        return null;
    }
}

public String getAsString(FacesContext fc, UIComponent uic, Object object) {
    if(object != null) {
        return String.valueOf(((Visitante) object).getCodigo());
    }
    else {
        return null;
    }
}   
}

@ManagedBean(name="visitaService", eager = true)
@ApplicationScoped
public class VisitaService {
 
private List<Visitante> visitas; 

 
public List<Visitante> getVisitas() {
	return visitas;
}

public void setVisitas(List<Visitante> visitas) {
	this.visitas = visitas;
} 
}