<html>
<head>
 <title>Title</title>
 <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
</head>
<body>
<form enctype="multipart/form-data" id="form_example">
 <input type="file" id="files" multiple/><br/><br/>
 <input type="submit" value="提交"/>
</form>

<div id='file-list-display'></div>
</body>
</html>

js代碼：

<script type="text/javascript">
 $(document).ready(function () {
  var fileList = [];
  var fileCatcher = document.getElementById('form_example');
  var files = document.getElementById("files"), renderFileList;
  var fileListDisplay = document.getElementById('file-list-display'), sendFile;

  fileCatcher.addEventListener("submit", function (event) {
   event.preventDefault();
   //上傳文件
   sendFile();
  });

  files.addEventListener("change", function (event) {
   for (var i = 0; i < files.files.length; i++) {
    fileList.push(files.files[i]);
   }
   renderFileList();
  });

  renderFileList = function () {
   fileListDisplay.innerHTML = '';
   fileList.forEach(function (file, index) {
    var fileDisplayEl = document.createElement("p");
    fileDisplayEl.innerHTML = (index + 1) + ":" + file.name;
    fileListDisplay.appendChild(fileDisplayEl);
   })
  };

  sendFile = function () {
   var formData = new FormData();
   var request = new XMLHttpRequest();
   //循環(huán)添加到formData中
   fileList.forEach(function (file) {
    formData.append('files', file, file.name);
   })
   request.open("POST", "/test/upload.do");
   request.send(formData);
  }
 })
</script>

后端使用Spring MVC接收前端文件

配置multipart解析器：

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"
   p:defaultEncoding="utf-8"/>

Controller：

@RequestMapping("/upload.do")
@ResponseBody
public Object upload(@RequestParam MultipartFile[] files) {
  System.out.println(files.length);
  return "ok";
}

前端頁面：