net.sf.jasperreports.engine.JRException：没有提供给导出器的输入源

Question

我有一个例外。 “net.sf.jasperreports.engine.JRException：没有提供给导出器的输入源”。

源代码（在jsp文件中）：

try {
    CustomerReport report = new CustomerReport();
    report.setReportType((Integer) session.getAttribute("reportType"));
    report.setEndTime((String) session.getAttribute("endTime"));
    report.setBeginTime((String) session.getAttribute("beginTime"));
    List<CustomerStatistics> stasList =
            (List<CustomerStatistics>) session.getAttribute("stasList");
    dataSize = stasList.size();
    ds = report.getDataSource(stasList).toString();
    JasperPrint print = report.getPrint(stasList);

    JRHtmlExporter exporter = new JRHtmlExporter();
    session.setAttribute(ImageServlet.DEFAULT_JASPER_PRINT_SESSION_ATTRIBUTE, print);
    exporter.setParameter(JRExporterParameter.JASPER_PRINT, print);
    exporter.setParameter(JRExporterParameter.OUTPUT_WRITER, out);
    exporter.setParameter(JRHtmlExporterParameter.IS_USING_IMAGES_TO_ALIGN, true);
    exporter.setParameter(JRHtmlExporterParameter.IMAGES_URI, "../servlets/image?image=");

    exporter.exportReport();
} catch (Exception e) {
    logger.error(this.getClass(), e);
}

CustomerReport代码：

public JasperPrint getPrint(List<CustomerStatistics> stasList) {
    JasperPrint print = null;
    FontBuilder boldFont = stl.fontArialBold().setFontSize(12).setFontName("SansSerif");
    TextColumnBuilder<String> areaNameColumn = col.column("区域", "areaName", type.stringType());
    TextColumnBuilder<Integer> businessConsultColumn = col.column("业务咨询", "businessConsultSum", type.integerType());
    TextColumnBuilder<Integer> openReserveColumn = col.column("开通预约", "openReserveSum", type.integerType());
    TextColumnBuilder<Integer> complainAcceptColumn = col.column("投诉受理", "complainAcceptSum", type.integerType());

    try {
        print = report()
                .setPageFormat(900, 600, PageOrientation.PORTRAIT)
                .setTemplate(Templates.reportTemplate)
                .title(Templates.createTitleComponent(title + "   [ " + beginTime + " 至 " + endTime + " ]"))
                .summary(
                        cht.bar3DChart()
                                .setShowValues(true)
                                .setTitleFont(boldFont)
                                .setCategory(areaNameColumn)
                                .series(cht.serie(businessConsultColumn), cht.serie(openReserveColumn), cht.serie(complainAcceptColumn))
                                .setCategoryAxisFormat(
                                        cht.axisFormat().setLabel("区域"))
                )
                .pageFooter(Templates.footerComponent)
                .setDataSource(getDataSource(stasList))
                .toJasperPrint();


    } catch (Exception e) {
        logger.error("________________****   getPrint()   ***____________________");
        logger.error(this.getClass(), e);
    }

public JRDataSource getDataSource(List<CustomerStatistics> stasList) {
    DRDataSource ds =
            new DRDataSource("areaName", "businessConsultSum", "openReserveSum", "complainAcceptSum");
    for (CustomerStatistics stas : stasList) {

        ds.add(stas.getAreaName(), stas.getBusinessConsultSum(),
                stas.getOpenReserveSum(), stas.getComplainAcceptSum());
    }

    return ds;
}

动作功能源代码：

stasList=customerStatisticsService.getCustomerStatisList(map);
if(stasList==null||stasList.size()<=0)  {
    isNoData = true;
    noDataHide = true;
}

HttpSession session = ServletActionContext.getRequest()
        .getSession();
session.setAttribute("reportType",reportType);
session.setAttribute("stasList",stasList);
session.setAttribute("reportTitle",reportTitle);
session.setAttribute("beginTime",beginTime);
session.setAttribute("endTime",endTime);
String dir = System.getProperty("user.dir");
session.setAttribute("dir",dir);