Java 使用xls格式创建jasper报表时出现内存错误

我正在使用jasper report创建报告。当我创建包含12000条记录的报告（pdf，xls）时，工作正常，但当我创建包含40000条记录的报告时，堆内存问题严重。问题只在于xls格式。pdf格式很好用。我的代码如下

Map hm = new HashMap();
JasperPrint print = null;
JRSwapFileVirtualizer virtualizer = null;
    JRSwapFile swapFile = new JRSwapFile("D://", 2048, 1024);
virtualizer = new JRSwapFileVirtualizer(2,swapFile,true);
JRVirtualizationHelper.setThreadVirtualizer(virtualizer);
hm.put(JRParameter.REPORT_VIRTUALIZER, virtualizer);
JRBeanCollectionDataSource beanColDataSource = new JRBeanCollectionDataSource(
                    list);
JRExporter exporter = null;
            if (type.toUpperCase().equalsIgnoreCase(FileTypes.PDF.name())) {
                exporter = new JRPdfExporter();

            } else if (type.toUpperCase().equalsIgnoreCase(FileTypes.XLS.name())) {
                exporter = new JRXlsExporter();
            }

            if(exporter != null)
            {
                exporter.setParameter(JRExporterParameter.OUTPUT_FILE_NAME,
                        outFileName);
                exporter.setParameter(JRExporterParameter.JASPER_PRINT, print);
                exporter.exportReport();
            }

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我找到了这个问题的答案。我已经在xls文件中添加了IS_IGNORE_分页，因此它可以正常工作

Map hm = new HashMap();
JasperPrint print = null;
JRSwapFileVirtualizer virtualizer = null;
JRSwapFile swapFile = new JRSwapFile("D://", 2048, 1024);
virtualizer = new JRSwapFileVirtualizer(2,swapFile,true);
JRVirtualizationHelper.setThreadVirtualizer(virtualizer);
hm.put(JRParameter.REPORT_VIRTUALIZER, virtualizer);
if (type.toUpperCase().equalsIgnoreCase(FileTypes.XLS.name()))
{
    hm.put(JRParameter.IS_IGNORE_PAGINATION, new Boolean(false));
}
JRBeanCollectionDataSource beanColDataSource = new JRBeanCollectionDataSource(
                    list);
JRExporter exporter = null;
            if (type.toUpperCase().equalsIgnoreCase(FileTypes.PDF.name())) {
                exporter = new JRPdfExporter();

            } else if (type.toUpperCase().equalsIgnoreCase(FileTypes.XLS.name())) {
                exporter = new JRXlsExporter();
            }

            if(exporter != null)
            {
                exporter.setParameter(JRExporterParameter.OUTPUT_FILE_NAME,
                        outFileName);
                exporter.setParameter(JRExporterParameter.JASPER_PRINT, print);
                exporter.exportReport();
            }