一:引入所需jar包

// https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload
compile group: 'commons-fileupload', name: 'commons-fileupload', version: '1.3.1'
// https://mvnrepository.com/artifact/commons-io/commons-io
compile group: 'commons-io', name: 'commons-io', version: '2.4'

二:配置文件application.xml
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="104857600" />
<property name="maxInMemorySize" value="4096" />
<property name="defaultEncoding" value="UTF-8"/>
</bean>

三:编写后台
@RequestMapping(value = "/licenseUpload")
    @ResponseBody
    public JSONObject licenseUpLoad(@RequestParam("file") MultipartFile file) {

        JSONObject jsonObject = new JSONObject();
        //判断文件是否为空
        if (!file.isEmpty()) {
            String uploadUrl = PropertyUtil.getValue("upload.url"); // 获取存放路径,可自定义
            String fileName = file.getOriginalFilename(); //获取文件名称
            try {
                file.transferTo(new File(uploadUrl + "//" + fileName));
                jsonObject.put("status", 1);
            } catch (IOException e) {
                jsonObject.put("status", e.getMessage());
                ExceptionUtil.showExceptionMessage(e);
            }
        } else {
            jsonObject.put("status", "未上传文件");
        }

        return jsonObject;
    }

 四:前端

<form action="http://localhost:8080/license/licenseUpload" method="post" enctype="multipart/form-data">
  选择文件:
  <input type="file" name="file">
  <br/>
  <button type="submit" value="提交">
</form>