@Override
  public String printFile(Long id) throws IOException {
    try {
      FileDypeVo fileDypeVos = fileMapper.selectFileId(id);
      String path = fileDypeVos.getFilePath();
      String name = fileDypeVos.getFileName();
      File file = new File(path + name);
      // 获取后缀
      String str = name.substring(name.lastIndexOf(".") + 1);
      // 获取前面的名字
      String str1 = name.substring(0, name.lastIndexOf(".") - 1);
      // 拼装为pdf
      String str2 = str1 + ".pdf";
      LOGGER.info("str==》" + str);
      LOGGER.info("str1===>" + str1);
      LOGGER.info("str2===>" + str2);
      LOGGER.info("file===>" + file);
      BASE64Encoder encoder = new BASE64Encoder();
      if (str.equals("pdf")) {
        FileInputStream inputFile = new FileInputStream(file);
        byte[] buffer = new byte[(int) file.length()];
        inputFile.read(buffer);
        inputFile.close();
        System.out.println("pdf预览成功");
        return encoder.encode(buffer);
      }
      if (str.equals("docx") || str.equals("doc")) {
        String sourcePath = path + name;
        String targetPath = path + str2;
        String files01 = str2;
        LOGGER.info("sourcePath==>" + sourcePath + "==>targetPath==>" + targetPath + "==files" + files01);
        File fileYan = new File(targetPath);
        // 查看是否生成过pdf了查看文件是否是存在 不存在则进入 存在不执行
        if (!fileYan.exists()) {
          ExcelPdToWord.documents4jWordToPdf(sourcePath, targetPath);
        }
        FileInputStream inputFile = new FileInputStream(fileYan);
        byte[] buffer = new byte[(int) fileYan.length()];
        inputFile.read(buffer);
        inputFile.close();
        System.out.println("pdf预览成功");
        return encoder.encode(buffer);
      } else {
        throw new ServiceException("该文档格式无法预览");
      }
    } catch (Exception e) {
      throw new ServiceException("预览失败" + e.getMessage());
      // TODO: handle exception
    }
  }

/**
     * 通过documents4j 实现word转pdf
     *
     * @param sourcePath 源文件地址 如 /root/example.doc
     * @param targetPath 目标文件地址 如 /root/example.pdf
     */
    public static void documents4jWordToPdf(String sourcePath, String targetPath) {
        File inputWord = new File(sourcePath);
        File outputFile = new File(targetPath);
        try  {
            InputStream docxInputStream = new FileInputStream(inputWord);
            OutputStream outputStream = new FileOutputStream(outputFile);
            IConverter converter = LocalConverter.builder().build();
            converter.convert(docxInputStream)
                    .as(DocumentType.DOCX)
                    .to(outputStream)
                    .as(DocumentType.PDF).execute();
            outputStream.close();
        } catch (Exception e) {
          LOGGER.error("[documents4J] word转pdf失败:{}"+ e.toString());
           // log.error("[documents4J] word转pdf失败:{}", e.toString());
        }
    }

<dependency>
      <groupId>com.documents4j</groupId>
      <artifactId>documents4j-local</artifactId>
      <version>1.0.3</version>
    </dependency>
    <dependency>
      <groupId>com.documents4j</groupId>
      <artifactId>documents4j-transformer-msoffice-word</artifactId>
      <version>1.0.3</version>
          </dependency>

compile group: 'com.documents4j', name: 'documents4j-local', version: '1.0.3'
     // https://mvnrepository.com/artifact/com.documents4j/documents4j-transformer-msoffice-word
     compile group: 'com.documents4j', name: 'documents4j-transformer-msoffice-word', version: '1.0.3'
     compile group: 'com.documents4j', name: 'documents4j-api', version: '1.0.3'
  // https://mvnrepository.com/artifact/com.documents4j/documents4j-transformer
     compile group: 'com.documents4j', name: 'documents4j-transformer', version: '1.0.3'
     compile group: 'com.documents4j', name: 'documents4j-transformer-api', version: '1.0.3'
     compile group: 'com.documents4j', name: 'documents4j-transformer-msoffice-base', version: '1.0.3'
     compile group: 'com.documents4j', name: 'documents4j-util-all', version: '1.0.3'
     compile group: 'com.documents4j', name: 'documents4j-util-conversion', version: '1.0.3'
     compile group: 'com.documents4j', name: 'documents4j-util-transformer-process', version: '1.0.3'
     compile group: 'org.zeroturnaround', name: 'zt-exec', version: '1.8'