AJAX上传文件

<form   id="uploadForm"  method="post" enctype="multipart/form-data">
   <label  >上传电子书</label>
   <input type="file"  name="file" >
   <button  id="upload" type="button"  name="button" >上传</button>
</form>

$("#upload").click(function () {
   var formData = new FormData($('#uploadForm')[0]);
   $.ajax({
    type: 'post',
    url: "https://****:8443/fileUpload", //上传文件的请求路径必须是绝对路劲
     data: formData,
     cache: false,
     processData: false,
     contentType: false,
      }).success(function (data) {
        console.log(data);
        alert("上传成功"+data);
        filename=data;
      }).error(function () {
         alert("上传失败");
     });
    });

@PostMapping(value = "/fileUpload")
    @ResponseBody
    public String  fileUpload(@RequestParam(value = "file") MultipartFile file, Model model, HttpServletRequest request) {
        if (file.isEmpty()) {
            System.out.println("文件为空空");
        }
            String fileName = file.getOriginalFilename();  // 文件名
            System.out.println(file.getOriginalFilename());
            String suffixName = fileName.substring(fileName.lastIndexOf("."));  // 后缀名
            String filePath = "C://pdf//"; // 上传后的路径
            fileName = UUID.randomUUID() + suffixName; // 新文件名
            File dest = new File(filePath + fileName);
            System.out.println("pdf文件路径为："+dest.getPath());
            if (!dest.getParentFile().exists()) {
                dest.getParentFile().mkdirs();
                System.out.println("上传pdf文件+++++++++++");
                System.out.println("pdf文件路径为："+dest.getPath());
            }
            try {
                file.transferTo(dest);
            } catch (IOException e) {
                e.printStackTrace();
            }
            String filename = "/pdf/" + fileName;
          return fileName;


    }