最后，我找到了从字节数组下载文件的解决方案
在download.jspx中：

<af:commandButton text="Печать" id="cbPrint"
                                styleClass="AFStretchWidth btn btn-default"
                                inlineStyle="text-align:center; width:100.0px; font-size:14px;margin:10px">
                <af:fileDownloadActionListener filename="download.pdf"
                                               contentType="application/pdf"
                                               method="#{RequestBean.downloadReport}"/>
              </af:commandButton>

在requestbean.java中

public void downloadReport(FacesContext facesContext,
                               OutputStream outputStream) {
        try {
            outputStream.write(getPrintBytes());
            outputStream.flush();
            outputStream.close();
        } catch (Exception e) {
            logger.log(Level.SEVERE, "downloadReport", e);
        }
        facesContext.responseComplete();
    }