如何在jsp中显示jasper报告

Question

我已经使用 ireport 设计了 ​​jasper 报告，我想从 jsp 调用该报告，并且我已经使用 sql 查询构建了报告。

Answer 1

您需要在单击 jsp 文件中的按钮或图像时调用 servlet。在 servlet 中编译你的 jrxml（jasper 报告格式）。然后您需要编写代码来下载该 servlet。

以下代码用于编译jasper报告并导出到特定文件夹：

HashMap<String, Object> response = new HashMap<String, Object>();
        String fileName = "C:\\temp\\report.jrxml"; 
        String pdfFile = "C:\\temp\\";
        JasperReport mainReport;
        JasperDesign mainReportDesign;

        try {
            mainReportDesign = JRXmlLoader.load(fileName);
            mainReport = JasperCompileManager.compileReport(mainReportDesign);
            if(reportFormat.equalsIgnoreCase("PDF"))
                pdfFile = pdfFile+"report.pdf";
            else if(reportFormat.equalsIgnoreCase("CSV"))
                pdfFile = pdfFile+"report.csv";
            JasperPrint jasperPrint = JasperFillManager.fillReport(mainReport, params, new JREmptyDataSource());


            if(reportFormat.equalsIgnoreCase("PDF"))
                JasperExportManager.exportReportToPdfFile(jasperPrint, pdfFile);
            else if(reportFormat.equalsIgnoreCase("CSV")) {
                JRExporter exporter = new JRCsvExporter();
                exporter.setParameter(JRExporterParameter.OUTPUT_FILE_NAME, pdfFile);
                exporter.setParameter(JRExporterParameter.JASPER_PRINT, jasperPrint);
                exporter.exportReport();
            }

        } catch (JRException e) {
            e.printStackTrace();
       }

下面的代码用于从该文件夹下载该导出文件。这将在您的 servlet 类中：

        File  f        = new File("C:\\temp\\report.pdf");
        int                 length   = 0;
        ServletOutputStream op       = resp.getOutputStream();
        ServletContext      context  = getServletConfig().getServletContext();
        String              mimetype = context.getMimeType(f.getName());

        resp.setContentType( (mimetype != null) ? mimetype : "application/octet-stream" );
        resp.setContentLength( (int)f.length() );
        resp.setHeader( "Content-Disposition", "attachment; filename="+reportName );

        byte[] bbuf = new byte[1024];
        DataInputStream in = new DataInputStream(new FileInputStream(f));

        while ((in != null) && ((length = in.read(bbuf)) != -1))
        {
            op.write(bbuf,0,length);
        }

        in.close();
        op.flush();
        op.close();