Java使用itext5实现生成多个PDF并合并

    /**
     * 根据id查询数据
     * @param id 数据id
     * @return
     */
    private Map<String, String> queryEntityDataById(String id) {
        //根据id查询
        Box entity = BoxService.getById(id);

        Map<String, String> data = new HashMap<String, String>();
        //显示内容
        //id
        data.put("id", entity.getJdKh());
        //动态生成当前时间的yymmddhh格式
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyMMddHH");
        String currentDate = LocalDateTime.now().format(formatter);
        data.put("date", currentDate);

        //二维码内容
        data.put("imsi", entity.getImsi());
        data.put("imei", entity.getImei());

        String type = entity.getType();
        if (type == null || type.isEmpty()) {
            type = "A";
        }
        data.put("type", type);
        return data;
    }

    //根据数据生成PDF
    private void generatePdfForData(Map<String, String> data, ByteArrayOutputStream outputStream) throws Exception {
        // Load the PDF template
        InputStream templateStream = getClass().getResourceAsStream("/template/ddentitytemplate.pdf");
        PdfReader reader = new PdfReader(templateStream);
        PdfStamper stamper = new PdfStamper(reader, outputStream);

        AcroFields form = stamper.getAcroFields();
        String fontPath = File.separator + "font" + File.separator + "micosoftyh.ttf";
        BaseFont bfChinese = BaseFont.createFont(fontPath, BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
        Map<String, AcroFields.Item> fields = form.getFields();
        for (String k : fields.keySet()) {
            form.setFieldProperty(k, "textfont", bfChinese, null);
            form.setFieldProperty(k, "textsize", Float.valueOf("55"), null);
            form.setFieldProperty(k, "textstyle", com.itextpdf.text.Font.BOLD, null);
            form.setFieldProperty(k, "textalign", Element.ALIGN_MIDDLE, null);
        }
        //特殊文本框字体大小重置
        form.setFieldProperty("$serialnumber$", "textsize", Float.valueOf("40"), null);
        //标签内容
        //ID
        form.setField("$id$", data.get("id"));
        //日期
        form.setField("$date$", data.get("date"));

        //二维码
        String qrContent = String.format(
                        "ID:%s\n" +
                        "IMSI:%s\n" +
                        "IMEI:%s\n" +
                        "type:%s",
                data.get("id"), data.get("imsi"), data.get("imei"),data.get("type"));
        PdfContentByte cb = stamper.getOverContent(1);
        generateQRcode(qrContent, cb);
        stamper.setFormFlattening(true);
        stamper.close();
        reader.close();
    }

    /**
     * 根据ID批量生成pdf并合并
     * @param ids ids集合
     * @return 可直接访问的pdf流文件
     */
    @GetMapping("/generateMergePdfStream")
    public ResponseEntity<ByteArrayResource> generateMergePdfStream(@RequestParam String ids) {
        long startTime = System.currentTimeMillis();
        System.out.println("开始生成PDF: " + startTime);
        try {
            String[] idArray = ids.split(",");
            ByteArrayOutputStream mergedOutputStream = new ByteArrayOutputStream();
            Document mergedDocument = new Document();
            PdfSmartCopy copy = new PdfSmartCopy(mergedDocument, mergedOutputStream);
            mergedDocument.open();

            for (String id : idArray) {
                Map<String, String> data = queryEntityDataById(id.trim());

                ByteArrayOutputStream pdfOutputStream = new ByteArrayOutputStream();
                generatePdfForData(data, pdfOutputStream);

                System.out.println("生成的PDF文件大小: " + pdfOutputStream.size());

                PdfReader reader = new PdfReader(new ByteArrayInputStream(pdfOutputStream.toByteArray()));
                copy.addDocument(reader);
                reader.close();
                pdfOutputStream.close();
            }

            mergedDocument.close();

            ByteArrayResource resource = new ByteArrayResource(mergedOutputStream.toByteArray());

            HttpHeaders headers = new HttpHeaders();
            headers.add("Content-Disposition", "inline; filename=merged.pdf");

            long generationEnd = System.currentTimeMillis();
            System.out.println("PDF生成与合并完成，总耗时: " + (generationEnd - startTime) + " 毫秒");

            return ResponseEntity.ok()
                    .headers(headers)
                    .contentType(MediaType.APPLICATION_PDF)
                    .body(resource);

        } catch (Exception e) {
            e.printStackTrace();
            return ResponseEntity.status(500).build();
        }
    }

#访问jar包位置的同级files文件，可以直接通过http://IP:port/files下的文件名访问
spring.web.resources.static-locations=file:./files/

    /**
     * 生成合并的pdf文件保存到服务器下面
     * application.properties下面需要配置spring.web.resources.static-locations=file:./files/
     * jar包运行的文件夹目录
     * @param ids ids集合
     * @return 可直接访问的http://IP:Port/*.pdf
     */
    @GetMapping("/generateentityLogPdf")
    public ResponseEntity generateMergeSavePdf(@RequestParam String ids, HttpServletRequest request) {
        try {
            // 分割ids
            String[] idArray = ids.split(",");

            // 输出流
            ByteArrayOutputStream mergedOutputStream = new ByteArrayOutputStream();
            Document mergedDocument = new Document();
            PdfCopy copy = new PdfCopy(mergedDocument, mergedOutputStream);
            mergedDocument.open();

            for (String id : idArray) {
                //根据id查询pdf所需要数据
                Map<String, String> data = queryEntityDataById(id.trim());

                // 根据id生成pdf数据流
                ByteArrayOutputStream pdfOutputStream = new ByteArrayOutputStream();
                generatePdfForData(data, pdfOutputStream);

                // 将生成的pdf数据流
                PdfReader reader = new PdfReader(new ByteArrayInputStream(pdfOutputStream.toByteArray()));
                copy.addDocument(reader);
                reader.close();
            }

            mergedDocument.close();

            //保存文件路径
            String currentDateDir = LocalDate.now().format(DateTimeFormatter.ofPattern("yyyyMMdd"));
            // 获取运行目录下的 files 目录路径
            String filePath = System.getProperty("user.dir") + File.separator + "files" + File.separator + currentDateDir;
            File directory = new File(filePath);

            // 检查目录是否存在，不存在则创建
            if (!directory.exists()) {
                directory.mkdirs();
            }

            // 保存文件名
            Random random = new Random();
            int randomNumber = random.nextInt(1000);
            String fileName = System.currentTimeMillis() + "_" + randomNumber + ".pdf";

            File file = new File(directory, fileName);
            try (FileOutputStream fos = new FileOutputStream(file)) {
                fos.write(mergedOutputStream.toByteArray());
                fos.flush();
                System.out.println("文件保存成功：" + file.getAbsolutePath());
            } catch (IOException e) {
                e.printStackTrace();
            }
            //返回直接访问pdf的url
            String ip = request.getServerName();
            int port = request.getServerPort();
            String fileUrl = "http://" + ip + ":" + port + "/" + currentDateDir + "/" + fileName;
            return ResponseEntity.ok(fileUrl);
        } catch (Exception e) {
            e.printStackTrace();
            return ResponseEntity.status(500).build();
        }
    }