大橙子

        private MimetypesFileTypeMap mtftp;

        mtftp = new MimetypesFileTypeMap();
        mtftp.addMimeTypes("image png tif jpg jpeg bmp");
        String contentType;
        try {
            contentType = mtftp.getContentType(multipartFileToFile(multipartFile));
        } catch (IOException e) {
            e.printStackTrace();
        }
        String type = contentType.split("/")[0];
        if(!"image".equals(type)){
            //非图片类型
        }

    /**
     * MultipartFile 转 File
     *
     * @param file
     * @throws Exception
     */
    public File multipartFileToFile(MultipartFile file) throws IOException {

        File toFile = null;
        if (file.equals("") || file.getSize() <= 0) {
            file = null;
        } else {
            InputStream ins = null;
            ins = file.getInputStream();
            toFile = new File(file.getOriginalFilename());
            inputStreamToFile(ins, toFile);
            ins.close();
        }
        return toFile;
    }
    //获取流文件
    private void inputStreamToFile(InputStream ins, File file) {
        try {
            OutputStream os = new FileOutputStream(file);
            int bytesRead = 0;
            byte[] buffer = new byte[8192];
            while ((bytesRead = ins.read(buffer, 0, 8192)) != -1) {
                os.write(buffer, 0, bytesRead);
            }
            os.close();
            ins.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }