<p>Files List</p>
<h:form prependId="false">
    <p:dataTable value="#{pc_ArchiveFiles.archiveFiles}" var="fs"
        paginator="true" rows="5"
        paginatorTemplate="{CurrentPageReport}  {FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink} {RowsPerPageDropdown}"
        rowsPerPageTemplate="5,10,15">
        <f:facet name="header">
            Client Files
        </f:facet>
        <p:column>
            <f:facet name="header">
                File Name
            </f:facet>
             <h:outputText value="#{fs.fileName}" />
        </p:column>
        <p:column>
            <f:facet name="header">
                File Size
            </f:facet>
            <h:outputText value="#{fs.fileSizeInKB}" />
        </p:column>
        <p:column>
            <f:facet name="header">
               Download File
            </f:facet>
            <p:commandLink id="downloadLink" value="Download" ajax="false">
                    <p:fileDownload value="#{pc_ArchiveFiles.downloadPDF}" />
            </p:commandLink>
        </p:column>
    </p:dataTable>
</h:form>

@ManagedBean(value = "pc_ArchiveFiles")
@RequestScoped
public class ArchiveFiles extends PageCodeBase {
private static final Logger logger = LoggerFactory
        .getLogger(ArchiveFiles.class);
 @Value("${archive.location}")
private String repository;
public List<ArchiveFile> getArchiveFiles() {


    Map<String, String> params = FacesContext.getCurrentInstance()
            .getExternalContext().getRequestParameterMap();
    subCategory = params.get("categoryName");

    // Build request object
    ArchiveFilesRequest request = new ArchiveFilesRequest();
    request.setCaseWorkerId(SecurityUtil.getLoggedInUser().getLoggedUserId());
    request.setClientId(getSelectedConsumer().getConsumerId());
    request.setCategoryName(subCategory);
    ArchiveFilesResponse response = archiveService.getArchiveFiles(request);
    if((response.getResponseType() == ResponseType.SUCCESS || response.getResponseType() == ResponseType.WARNING) && response.getFileCount() > 0) { // There is at least one file
        archiveFiles = new ArrayList<ArchiveFile>();
        archiveFiles.addAll(response.getFileSet());
        return archiveFiles;
    } else {
        return Collections.<ArchiveFile> emptyList();
    }
}


 public void downloadPDF() throws IOException {

        FacesContext facesContext = FacesContext.getCurrentInstance();
        ExternalContext externalContext = facesContext.getExternalContext();
        HttpServletResponse response = (HttpServletResponse) externalContext.getResponse();

        facesContext.responseComplete();
    }

<h:commandLink id="downloadLink" value="Download PDF" target="_blank" action="#{pc_ArchiveFiles.downloadPDF}" />

<p:commandButton id="downloadLink" value="Download" ajax="false" onclick="PrimeFaces.monitorDownload(start, stop)"
        icon="ui-icon-arrowthichk-s">
    <p:fileDownload value="#{fileDownloadController.file}" />
</p:commandButton>



 private StreamedContent file;
 public StreamedContent getFile() {
        return file;
    }
public void setFile(StreamedContent file){
 InputStream stream = ((ServletContext)FacesContext.getCurrentInstance().getExternalContext().getContext()).getResourceAsStream("/images/optimusprime.jpg");
        file = new DefaultStreamedContent(stream, "image/jpg", "downloaded_optimus.jpg");
}

<h:commandLink id="downloadLink" value="Download PDF" target="_blank" actionListener="#{pc_ArchiveFiles.downloadPDF}" />