问JasperReports: fillReport非常慢

EN

DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
FileInputStream fileStream = new FileInputStream(rawXmlFile);
ds = docBuilder.parse(fileStream);

Map<String, Object> params = new HashMap<String, Object>();
params.put(JRXPathQueryExecuterFactory.PARAMETER_XML_DATA_DOCUMENT, ds);
params.put(JRXPathQueryExecuterFactory.XML_DATE_PATTERN, com.vodafone.gdsp.reporting.enums.xml.DateFormat.DATE_FORMAT_ISO8601);
params.put(JRXPathQueryExecuterFactory.XML_NUMBER_PATTERN, "##0.##");
params.put(JRXPathQueryExecuterFactory.XML_LOCALE, Locale.ENGLISH);
params.put(JRParameter.REPORT_LOCALE, Locale.UK);
params.put("REPORT_DIR", jasperFile.substring(0, jasperFile.lastIndexOf("/")));

try {
    virtPageSize = Integer.parseInt(reportConfig.getJasperVirtPageSize());
    virtPageDir = reportConfig.getJasperVirtPageDir();
} catch (NullPointerException npe) {
    logger.info("Virtual page size and directory not assigned, using the default value of virtPageSize {} and virtPageDir {}", virtPageSize, virtPageDir);
} catch (Exception ex) {
    logger.error("Exception while fetching virtual page size and directory {}", ex.getMessage());
}
logger.info("Using Jasper virtual parameters ({}, {})", virtPageSize, virtPageDir);

JRFileVirtualizer virtualizer = new JRFileVirtualizer(virtPageSize, virtPageDir);
JRVirtualizationHelper.setThreadVirtualizer(virtualizer);
params.put(JRParameter.REPORT_VIRTUALIZER, virtualizer);

DefaultJasperReportsContext context = DefaultJasperReportsContext.getInstance();
JRPropertiesUtil.getInstance(context).setProperty("net.sf.jasperreports.xpath.executer.factory",
    "net.sf.jasperreports.engine.util.xml.JaxenXPathExecuterFactory");

File jasperReport = new File(jasperFile);
JasperPrint jasperPrint = JasperFillManager.fillReport(new FileInputStream(jasperReport), params);