@RequestMapping(value = "/fileUpload", method = RequestMethod.POST)
	public ModelAndView fileUpload(
			@RequestParam("fileUpload") CommonsMultipartFile file) {
		System.out.println(file.getContentType());
		System.out.println(file.getSize());
		System.out.println(file.getOriginalFilename());
		
		String[][] answer = null;

		if (!file.isEmpty()) {
			String path = "/Users/mingyu_zhao/temp/" + file.getOriginalFilename();
			File localFile = new File(path);
			try {
				file.transferTo(localFile);
				answer = fileService.exchangeFile(path);
			} catch (IllegalStateException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return new ModelAndView("showFile", "answer", answer);
	}