poi-tl模板套红合并文件

这两天工作中遇到个需求，要求模板套红然后和另一个文档合并生成一个新文档。先讲下遇到的几个问题：

1、poi-tl只支持docx格式的文件，doc是不支持的

2、使用的文档一定不能是损坏的（测试时用的一个文档文件已经损坏，排查了很久）

public Result<String> mergeFiles(String headFileId, String mainFileId, List<KeyWordVo> keyWords) {
   try {
      byte[] headBytes = feginFileDownloadService.downloadFileByte(headFileId);//头文件字节数组
      InputStream headInputStream = new ByteArrayInputStream(headBytes);
      XWPFTemplate headTemplate = XWPFTemplate.compile(headInputStream).render(
         new HashMap<String, Object>(){{
            //模板套红
            if(null!=keyWords && keyWords.size()>0){
               keyWords.forEach(keyWordVo -> {
                  put(keyWordVo.getKey(),keyWordVo.getValue());
               });
            }
         }}
      );
      headInputStream.close();
      NiceXWPFDocument head = headTemplate.getXWPFDocument();//根据关键词填写完模板
      byte[] mainBytes = feginFileDownloadService.downloadFileByte(mainFileId);//主文件字节数组
      InputStream mainInputStream = new ByteArrayInputStream(mainBytes);
      NiceXWPFDocument main = new NiceXWPFDocument(mainInputStream);
      mainInputStream.close();
      // 合并两个文档
      NiceXWPFDocument newDoc = head.merge(main);

      // 生成新文档
      Attachment oldAttachment = feginDiscFileService.queryById(mainFileId);
      String contentType = ".doc".equals(oldAttachment.getPrefix())?CONTENT_TYPE_DOC:CONTENT_TYPE_DOCX;
      ByteArrayOutputStream out = new ByteArrayOutputStream();//二进制OutputStream
      newDoc.write(out);//文档写入流
      InputStream in = new ByteArrayInputStream(out.toByteArray());//OutputStream写入InputStream二进制流
      out.close();
      MultipartFile multipartFile = new MockMultipartFile("file", oldAttachment.getName(), contentType, in);
      in.close();
      //feginDiscFileService.deleteFile(oldAttachment.getId());//删除原文件
      Attachment newAttachment = feginDiscFileService.overwriteFile(multipartFile,oldAttachment.getId());//覆盖原文件
      System.out.println(newAttachment.toString());
      return Result.succeed("合并成功");
   } catch (IOException e) {
      e.printStackTrace();
      return Result.succeed("合并失败："+e.getMessage());
   } catch (Exception e) {
      System.out.println(e.getMessage());
      e.printStackTrace();
      return Result.succeed("合并失败："+e.getMessage());
   }
}