word ，pdf ，转图片通过base 64 转前端

@PostMapping("/convertToBase64/{fileRename}")
public AjaxResult convertToBase64(@PathVariable String fileRename) throws IOException {
List<String> base64Images = new ArrayList<>();
if (StringUtils.isEmpty(fileRename))
return AjaxResult.error("文件不能为空");
String result = businessManagementService.detailsNodeDataDownload(fileRename);
if (StringUtils.isEmpty(result) || result.contains("access")){
return AjaxResult.error("下载失败！");
}

    String fileUrl = result;
    int dotIndex = fileRename.lastIndexOf('.');
    String fileType =   fileRename.substring(dotIndex + 1);

    byte[] fileBytes;
    if ("pdf".equalsIgnoreCase(fileType)) {
        // 对PDF文件进行转换
        base64Images = convertPdfToBase64(fileUrl);
    } else if ("img".equalsIgnoreCase(fileType)||"png".equalsIgnoreCase(fileType)) {
        // 对图片文件进行转换
        fileBytes = convertImageToBase64(fileUrl);
        String base64File = "data:image/png;base64," + Base64.getEncoder().encodeToString(fileBytes);
        base64Images.add(base64File);

    } else if ("doc".equalsIgnoreCase(fileType)||"docx".equals(fileType)) {
        // 对Word文件进行转换
        base64Images = convertWordToBase64(fileUrl);

    } else {
        return error("Unsupported file type");
    }


    return success(base64Images);
}

private List<String> convertPdfToBase64(String imageUrl) throws IOException {
    // 从远程 URL 获取 PDF 文档
    URL url = new URL(imageUrl);
    try (PDDocument document = PDDocument.load(url.openStream())) {
        int numPages = document.getNumberOfPages();
        List<String> base64Images = new ArrayList<>();
        // 使用 PDFBox 将 PDF 转换为 BufferedImage
        PDFRenderer renderer = new PDFRenderer(document);
        for (int pageIndex = 0; pageIndex < numPages; pageIndex++) {
            BufferedImage image = renderer.renderImage(pageIndex);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ImageIO.write(image, "png", baos);

            byte[] imageBytes = baos.toByteArray();
            String base64Image = "data:image/png;base64," + Base64.getEncoder().encodeToString(imageBytes);

            base64Images.add(base64Image);
        }
        return base64Images;
    }
}

private byte[] convertImageToBase64(String imageUrl) throws IOException {
    URL url = new URL(imageUrl);
    BufferedImage image = ImageIO.read(url);
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ImageIO.write(image, "png", baos);

    return baos.toByteArray();
}

private List<String> convertWordToBase64(String wordFilePath) throws IOException {
    // 创建Document实例
    Document doc = new Document();
    List<String> base64Images = new ArrayList<>();
    InputStream inputStream = new URL(wordFilePath).openStream();
    // 加载Word文档
    doc.loadFromStream(inputStream, FileFormat.Auto);

    BufferedImage[] images = doc.saveToImages(0, doc.getPageCount(), ImageType.Bitmap, 500, 500);

    for (BufferedImage image : images) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ImageIO.write(image, "png", baos);
        String base64Image = "data:image/png;base64," + Base64.getEncoder().encodeToString(baos.toByteArray());

        base64Images.add(base64Image);
     //   base64Images.add("base64Image");
    }
    return base64Images;

}