上传图片文件时如何解决“所需的请求部分'文件'不存在”错误

Question

I have a problem when I try to send an (image) file from html to my spring controller, I did everything as same as when I send any other value but it keeps throwing this exact same error...

HTML

<form th:action="@{/changeLogo}" enctype="multipart/form-data" method="post">

  <div class="form-group">                                     
    <input type="file" name="file"/>                                     
  </div>  

  <button type="submit" class="text-center btn btn-primary"> Upload </button>                                  
</form>

Controller:

@PostMapping(value = "/changeLogo")
public String changelogo(@RequestParam("file") MultipartFile file, Principal principal){

    SystemUser systemUser = 
    systemUserService.findByUsername(principal.getName());
    Company company = systemUser.getCompany();

        try {
            System.out.println("Picture exists:" + file);
            company.setLogo(file.getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        }

    companyRepository.saveAndFlush(company);
    return "redirect:/systemUser";
}

Answer 1

Change

public String changelogo(@RequestParam("file") MultipartFile file, Principal principal)

to

public String changelogo(MultipartHttpServletRequest file)