使用MultipartFile的多个文件上传在Spring Boot中不起作用，从JSP在Controller中获取空数组

Question

I am using MultipartFile to upload multiple files. But from Jsp page when i select multiple files and click submit, I get empty array in controller.

Here are my code snippet,

in pom.xml

<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency> 

CommonsMultipartResolver Bean Config.

     @Bean
      public CommonsMultipartResolver multipartResolver() {
          CommonsMultipartResolver resolver=new CommonsMultipartResolver();
          resolver.setDefaultEncoding("utf-8");
          resolver.setMaxUploadSize(999999999);
          return resolver;
      }

JSP Code

<form:form method="POST" action="/createRequest"
        enctype="multipart/form-data">
        <input type="file" name="fileUpload" multiple />
        <br>
        <br><br>
        Select User
        <select name="userDirectory">
            <c:forEach items="${userslist}" var="user">
                <option value=${user.userDirectory}>${user.userName}</option>
            </c:forEach>

        </select>

        <input type="submit" value="Upload Files">
    </form:form>

Controller's Code

@PostMapping(value = "/createRequest")
    public ModelAndView createRequest(@RequestParam("fileUpload") MultipartFile[] fileUpload,
            @RequestParam("userDirectory") String userDirectory) throws IOException {

        log.info("In createRequest method");
        if (fileUpload != null && fileUpload.length > 0) {
            Flow not coming here because fileUpload.length coming zero.
        }
        return new ModelAndView("success");
    }

In controller fileUpload.length is coming zero from JSP page. Any help will be appriciated, Thanks.

Answer 1

private void initMultipartResolver(ApplicationContext context)
  {
    try
    {
      this.multipartResolver = ((MultipartResolver)context.getBean("multipartResolver", MultipartResolver.class));
      if (this.logger.isDebugEnabled()) {
        this.logger.debug("Using MultipartResolver [" + this.multipartResolver + "]");
      }
    }
    catch (NoSuchBeanDefinitionException ex)
    {
      this.multipartResolver = null;
      if (this.logger.isDebugEnabled())
        this.logger.debug("Unable to locate MultipartResolver with name 'multipartResolver': no multipart request handling provided");
    }
  }

Add this configuration, with this configuration , any request with enctype as multipart/form-data will be handled by multipartResolver before passing on to the Controller class.