Java 如何用JasperReportsContext替换JRParameter.REPORT\U FILE\U解析器的使用？

JR参数.REPORT\u FILE\u解析器在5.0版中不推荐使用。 Javadoc建议改用JasperReportsContext

如何使用JasperReportsContext

使用Struts2 jasper插件时需要使用

connection=dataSource.getConnection();
reportParams.put(JRParameter.REPORT_FILE_RESOLVER, new SimpleFileResolver(reportsDir));

我也有同样的问题（），几个小时后，我在JasperReports的资料中找到了答案

LocalJasperReportsContext ctx = new LocalJasperReportsContext(DefaultJasperReportsContext.getInstance());
ctx.setClassLoader(getClass().getClassLoader());
ctx.setFileResolver(new FileResolver() {
        @Override
        public File resolveFile(String s) {
            return new File(s);
        }
    });
JasperReport jasperReport = (JasperReport) JRLoader.loadObject(jasperfile);

JasperFillManager fillmgr = JasperFillManager.getInstance(ctx);
JasperExportManager exmgr = JasperExportManager.getInstance(ctx);

编辑： 正确的解决方案包括向插件的项目票务系统报告问题，并可能为解析器实现提供补丁

在等待补丁被接受时，您可以扩展

JasperReportsResult

类，只需使用上面的代码覆盖

doExecute（）

方法，如下所示：

protected void doExecute(String finalLocation, ActionInvocation invocation) throws Exception {
        // Will throw a runtime exception if no "datasource" property. TODO Best place for that is...?
        initializeProperties(invocation);

        LOG.debug("Creating JasperReport for dataSource = {}, format = {}", dataSource, format);

        HttpServletRequest request = (HttpServletRequest) invocation.getInvocationContext().get(ServletActionContext.HTTP_REQUEST);
        HttpServletResponse response = (HttpServletResponse) invocation.getInvocationContext().get(ServletActionContext.HTTP_RESPONSE);

        // Handle IE special case: it sends a "contype" request first.
        // TODO Set content type to config settings?
        if ("contype".equals(request.getHeader("User-Agent"))) {
            try (OutputStream outputStream = response.getOutputStream()) {
                response.setContentType("application/pdf");
                response.setContentLength(0);
            } catch (IOException e) {
                LOG.error("Error writing report output", e);
                throw new ServletException(e.getMessage(), e);
            }
            return;
        }

        // Construct the data source for the report.
        ValueStack stack = invocation.getStack();
        ValueStackDataSource stackDataSource = null;

        Connection conn = (Connection) stack.findValue(connection);
        if (conn == null)
            stackDataSource = new ValueStackDataSource(stack, dataSource, wrapField);

        if ("https".equalsIgnoreCase(request.getScheme())) {
            // set the the HTTP Header to work around IE SSL weirdness
            response.setHeader("CACHE-CONTROL", "PRIVATE");
            response.setHeader("Cache-Control", "maxage=3600");
            response.setHeader("Pragma", "public");
            response.setHeader("Accept-Ranges", "none");
        }

        // Determine the directory that the report file is in and set the reportDirectory parameter
        // For WW 2.1.7:
        //  ServletContext servletContext = ((ServletConfig) invocation.getInvocationContext().get(ServletActionContext.SERVLET_CONFIG)).getServletContext();
        ServletContext servletContext = (ServletContext) invocation.getInvocationContext().get(ServletActionContext.SERVLET_CONTEXT);
        String systemId = servletContext.getRealPath(finalLocation);
        Map parameters = new ValueStackShadowMap(stack);
        File directory = new File(systemId.substring(0, systemId.lastIndexOf(File.separator)));
        parameters.put("reportDirectory", directory);
        parameters.put(JRParameter.REPORT_LOCALE, invocation.getInvocationContext().getLocale());

        // put timezone in jasper report parameter
        if (timeZone != null) {
            timeZone = conditionalParse(timeZone, invocation);
            final TimeZone tz = TimeZone.getTimeZone(timeZone);
            if (tz != null) {
                // put the report time zone
                parameters.put(JRParameter.REPORT_TIME_ZONE, tz);
            }
        }

        // Add any report parameters from action to param map.
        Map reportParams = (Map) stack.findValue(reportParameters);
        if (reportParams != null) {
            LOG.debug("Found report parameters; adding to parameters...");
            parameters.putAll(reportParams);
        }

        ByteArrayOutputStream output;
        JasperPrint jasperPrint;

        LocalJasperReportsContext ctx = new LocalJasperReportsContext(DefaultJasperReportsContext.getInstance());
        ctx.setClassLoader(getClass().getClassLoader());
        ctx.setFileResolver(parameters.get());
        JasperReport jasperReport = (JasperReport) JRLoader.loadObject(jasperfile);

        JasperFillManager fillmgr = JasperFillManager.getInstance(ctx);
        JasperExportManager exmgr = JasperExportManager.getInstance(ctx);

        // Fill the report and produce a print object
        try {
            JasperReport jasperReport = (JasperReport) JRLoader.loadObject(new File(systemId));
            if (conn == null) {
                jasperPrint = fillmgr.fillReport(jasperReport, parameters, stackDataSource);
            }
            else {
                jasperPrint = fillmgr.fillReport(jasperReport, parameters, conn);
            }
        } catch (JRException e) {
            LOG.error("Error building report for uri {}", systemId, e);
            throw new ServletException(e.getMessage(), e);
        }

        // Export the print object to the desired output format
        try {
            if (contentDisposition != null || documentName != null) {
                final StringBuffer tmp = new StringBuffer();
                tmp.append((contentDisposition == null) ? "inline" : contentDisposition);

                if (documentName != null) {
                    tmp.append("; filename=");
                    tmp.append(documentName);
                    tmp.append(".");
                    tmp.append(format.toLowerCase());
                }

                response.setHeader("Content-disposition", tmp.toString());
            }

            JRExporter exporter;

            if (format.equals(FORMAT_PDF)) {
                response.setContentType("application/pdf");
                exporter = new JRPdfExporter(ctx);
            } else if (format.equals(FORMAT_CSV)) {
                response.setContentType("text/csv");
                exporter = new JRCsvExporter(ctx);
            } else if (format.equals(FORMAT_HTML)) {
                response.setContentType("text/html");

                // IMAGES_MAPS seems to be only supported as "backward compatible" from JasperReports 1.1.0

                Map imagesMap = new HashMap();
                request.getSession(true).setAttribute("IMAGES_MAP", imagesMap);

                exporter = new JRHtmlExporter(ctx);
                exporter.setParameter(JRHtmlExporterParameter.IMAGES_MAP, imagesMap);
                exporter.setParameter(JRHtmlExporterParameter.IMAGES_URI, request.getContextPath() + imageServletUrl);

                // Needed to support chart images:
                exporter.setParameter(JRExporterParameter.JASPER_PRINT, jasperPrint);
                request.getSession().setAttribute("net.sf.jasperreports.j2ee.jasper_print", jasperPrint);
            } else if (format.equals(FORMAT_XLS)) {
                response.setContentType("application/vnd.ms-excel");
                exporter = new JRXlsExporter(ctx);
            } else if (format.equals(FORMAT_XML)) {
                response.setContentType("text/xml");
                exporter = new JRXmlExporter(ctx);
            } else if (format.equals(FORMAT_RTF)) {
                response.setContentType("application/rtf");
                exporter = new JRRtfExporter(ctx);
            } else {
                throw new ServletException("Unknown report format: " + format);
            }

            Map exportParams = (Map) stack.findValue(exportParameters);
            if (exportParams != null) {
                LOG.debug("Found export parameters; adding to exporter parameters...");
                exporter.getParameters().putAll(exportParams);
            }

            output = exportReportToBytes(jasperPrint, exporter);
        } catch (JRException e) {
            LOG.error("Error producing {} report for uri {}", format, systemId, e);
            throw new ServletException(e.getMessage(), e);
        } finally {
            try {
                conn.close();
            } catch (Exception e) {
                LOG.warn("Could not close db connection properly", e);
            }
        }

        response.setContentLength(output.size());
        // Will throw ServletException on IOException.
        writeReport(response, output);
    }

然后在Struts中使用新扩展作为结果。请测试该方法是否正确实现

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最终的解决方案应该包括在结果对象上使用上下文实例设置器，或者可以从结果对象访问全局静态上下文实例。

我的问题（这么长）不太好。我使用jasper struts2插件，您需要传递参数（struts自己管理填充和导出操作）。我向struts传递了一个hashmap参数。在这个hashmap中，我放置了我的参数和文件解析器：reportParams.put（JRParameter.REPORT_FILE_RESOLVER，new SimpleFileResolver（reportsDir））；这就是我不想取代的东西。@Rydermark但这个问题的答案是正确的，不是吗？不幸的是，不，或者我不知道怎么做。也许你能更精确地描述一些事情。@Rydermark现在更明显了吗？您必须将文件解析器传递到上下文，而不是将其填充到

reportParams

。仍然不能。这个问题非常特定于Struts2 jasper插件，您不需要构建上下文。“以正常方式”生成ByteArrayOutputStream没有任何问题。使用插件时无法访问上下文。您只有参数映射、连接和报告的位置。非常感谢您的努力。请看下面的图片。你可以打开一个问题。