import net.sf.jasperreports.engine.fill.JRFileVirtualizer; //导入依赖的package包/类
private static JasperPrint fillReport(JRFileVirtualizer virtualizer) throws JRException
{
	long start = System.currentTimeMillis();

	// Virtualization works only with in memory JasperPrint objects.
	// All the operations will first fill the report and then export
	// the filled object.
	
	// creating the data source
	JRDataSource dataSource = new JREmptyDataSource(1000);
	
	// Preparing parameters
	Map<String, Object> parameters = new HashMap<String, Object>();
	parameters.put(JRParameter.REPORT_VIRTUALIZER, virtualizer);

	// filling the report
	JasperPrint jasperPrint = JasperFillManager.fillReport("build/reports/VirtualizerReport.jasper", parameters, dataSource);
	
	virtualizer.setReadOnly(true);

	System.err.println("Filling time : " + (System.currentTimeMillis() - start));
	return jasperPrint;
}
 

import net.sf.jasperreports.engine.fill.JRFileVirtualizer; //导入依赖的package包/类
public static void getDefaults(IPreferenceStore store) {
	store.setDefault(NSF_FILES_DELETE_ONEXIT, "true"); //$NON-NLS-1$
	store.setDefault(JSS_VIRTUALIZER_USE, "false"); //$NON-NLS-1$
	store.setDefault(JSS_VIRTUALIZER_TYPE, JRFileVirtualizer.class.getName());
	store.setDefault(JSS_VIRTUALIZER_MAX_SIZE, 100);
	store.setDefault(JSS_VIRTUALIZER_TMP, ""); //$NON-NLS-1$
	store.setDefault(JSS_VIRTUALIZER_BLOCK_SIZE, 100);
	store.setDefault(JSS_VIRTUALIZER_MIN_GROW_COUNT, 100);
	store.setDefault(JSS_VIRTUALIZER_PAGE_ELEMENT_SIZE, 1);

	store.setDefault(JSS_LIMIT_RECORDS, "false");//$NON-NLS-1$
	store.setDefault(JSS_MAX_RECORDS, -1);//$NON-NLS-1$
	store.setDefault(JSS_IGNOREPAGINATION, "false");//$NON-NLS-1$
	store.setDefault(JSS_REPORT_LOCALE, Locale.getDefault().toString());//$NON-NLS-1$
	store.setDefault(JSS_REPORT_TIMEZONE, TimeZone.getDefault().getID());//$NON-NLS-1$ 
}
 

import net.sf.jasperreports.engine.fill.JRFileVirtualizer; //导入依赖的package包/类
private void build() {
	TextColumnBuilder<String>     itemColumn     = col.column("Item",       "item",      type.stringType());
	TextColumnBuilder<Integer>    quantityColumn = col.column("Quantity",   "quantity",  type.integerType());
	TextColumnBuilder<BigDecimal> priceColumn    = col.column("Unit price", "unitprice", type.bigDecimalType());
	
	try {
		report()
		  .setTemplate(Templates.reportTemplate)
		  .columns(
		  	itemColumn, quantityColumn, priceColumn)
		  .title(Templates.createTitleComponent("Virtualizer"))
		  .pageFooter(Templates.footerComponent)
		  .setDataSource(createDataSource())
		  .setVirtualizer(new JRFileVirtualizer(2))
		  .show();
	} catch (DRException e) {
		e.printStackTrace();
	}
}
 

import net.sf.jasperreports.engine.fill.JRFileVirtualizer; //导入依赖的package包/类
/**
 *
 */
public void export() throws JRException
{
	// creating the virtualizer
	JRFileVirtualizer virtualizer = new JRFileVirtualizer(2, "tmp");

	JasperPrint jasperPrint = fillReport(virtualizer);

	exportPdf(jasperPrint);
	exportXml(jasperPrint, false);
	exportHtml(jasperPrint);
	exportCsv(jasperPrint);
	
	// manually cleaning up
	virtualizer.cleanup();
}
 

import net.sf.jasperreports.engine.fill.JRFileVirtualizer; //导入依赖的package包/类
/**
 * @return the jrVirtualizer
 */
public JRFileVirtualizer getJrVirtualizer() {
    return jrVirtualizer;
}
 

import net.sf.jasperreports.engine.fill.JRFileVirtualizer; //导入依赖的package包/类
/**
 * @param jrVirtualizer the jrVirtualizer to set
 */
public void setJrVirtualizer(JRFileVirtualizer jrVirtualizer) {
    this.jrVirtualizer = jrVirtualizer;
}
 

import net.sf.jasperreports.engine.fill.JRFileVirtualizer; //导入依赖的package包/类
@Override
protected void configureReport(JasperReportBuilder rb) {
	rb.title(cmp.text("title"))
	  .setVirtualizer(new JRFileVirtualizer(2));
}