本人遇到问题是错误信息如下：

org.springframework.web.multipart.support.MissingServletRequestPartException: Required request part 'file' is not present
	at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.handleMissingValue(RequestParamMethodArgumentResolver.java:199) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:114) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:167) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at 

前台Postman请求如图
headers:

Body:

后台接受方式：

    @PostMapping(value = "/importData")
    @Operation(method = "导入")
    public String importData(@RequestParam("file") MultipartFile fileNew){
        ResponseResult<Integer> responseResult = new ResponseResult<>();
        
        return outJsonString(responseResult);
    }

解决过程中，各种尝试，将参数换成字符串，只要使用了 @RequestParam标签，都会抛出如上异常，因为赶工期，没深入研究，后来使用项目中的其他用例，曲线救国，获取fileNew的方式如下：

    @PostMapping(value = "/importData)
    @Operation(method = "导入")
    public String importData(HttpServletRequest request){
        ResponseResult<Integer> responseResult = new ResponseResult<>();
        try {
            MultipartResolver resolver = new CommonsMultipartResolver(request.getSession().getServletContext());
            MultipartHttpServletRequest multipartRequest = resolver.resolveMultipart(request);
            MultipartFile fileNew = multipartRequest.getFile("file");

        } catch (Exception e) {
            responseResult.setSuccess(false);
            e.printStackTrace();
        }
        return outJsonString(responseResult);
    }

绕不过去的坑，始终要面对，后来简单写了个测试，发现 使用@RequestParam标签可以接受参数，后来来才看见，数据放在了 body中， @RequestParam是接收url参数中的数据，body需要使用 @RequestBody接收。特此梳理。