<script type="text/javascript" src="resources/js/jquery-3.3.1.min.js"></script>
  <script type="text/javascript" src="resources/js/ajaxFileUpload.js"></script>

 <!--使用springMVC上傳圖片 ajaxFileUpload-->
  <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <property name="maxUploadSize" value="10485760" />
  </bean>

 <input type="file" id="headImg" name="headImg"/>

function headImgUpload(){ //圖片上傳函數
  var results = "";
  var account = $("#account").val(); //account、identity 這兩個變量，根據我的需求會在后面用到，閱讀者可以根據自己的需求刪掉或者修改這兩個變量
  var identity = $("input[name='identity']:checked").val();
  $.ajaxFileUpload({
    url:"register/headImgUpload?account="+account+"&identity="+identity,//根據url訪問controller層中的方法
    secureuri:false,
    fileElementId:"headImg", //<input>標簽中的id屬性
    type:"POST",
    dataType:"text", //服務器返回的數據類型
    success:function (result) {
      result = result.replace(/<pre.*?>/g, ''); //ajaxFileUpload會對服務器響應回來的text內容加上<pre >text</pre>前后綴
      result = result.replace(/<PRE.*?>/g, '');
      result = result.replace("<PRE>", '');
      result = result.replace("</PRE>", '');
      result = result.replace("<pre>", '');
      result = result.replace("</pre>", '');
      result = JSON.parse(result);//轉換為json格式
      results = result.result;
      alert(result);
    },
    error:function (data,status,error) {
      alert("失敗！！！"+error);
    }
  });
}

@Controller
@RequestMapping(value = "register")
public class RegisterController {
  //用戶頭像上傳
  @RequestMapping(value = "/headImgUpload",method = RequestMethod.POST)
  @ResponseBody
  public Map<String,Object> headImgUpload(@RequestParam MultipartFile headImg, String account, String identity, HttpServletRequest request){
    //上傳的結果
    String result = "fail";
    //頭像上傳到的位置
    String imgRealPath = "";
    try{
      //確保上傳的圖片不為空
      if(headImg != null && !headImg.isEmpty()){
        //判斷注冊用戶的身份，商戶還是會員
        if(identity.equals("member")){
          //會員
          imgRealPath = request.getSession().getServletContext().getRealPath("/resources/image/member");
        }else if(identity.equals("businessman")){
          //商戶
          imgRealPath = request.getSession().getServletContext().getRealPath("/resources/image/businessman");
        }
        System.out.println(imgRealPath);//在控制臺打印一下路徑
        //上傳完成后保存的文件名
        String fileName= account + ".jpg";
        //文件夾不存在的話，新建一個
        File fileFolder = new File(imgRealPath);
        if(!fileFolder.exists()){
          fileFolder.mkdirs();
        }
        File file = new File(fileFolder,fileName);
        //transferTo(),springMVC的方法，用于圖片上傳時，將內存中的圖片寫入磁盤
        headImg.transferTo(file);//會報IO異常
        result = "success";
      }
    }catch (IOException e){
      e.printStackTrace();
    }
    Map<String,Object> resultMap = new HashMap<String,Object>();
    resultMap.put("result",result);
    return resultMap;
  }
}