1 问题现象

springboot、knife4j、swagger3整合后，swagger上文件上传接口的上传域出不来，无法进行调试，代码如下：

    @PostMapping(value = "/upload")
    @ApiOperation(value = "文件上传接口", notes = "文件上传接口")
    public ApiResult<UploadInfoVo> upload(MultipartFile uploadFile) throws Exception {
        return ApiResult.ok();
    }

swagger页面没有任何参数信息：

2 解决方式

可以使用@RequestPart注解，如下：

    @PostMapping(value = "/upload")
    @ApiOperation(value = "文件上传接口", notes = "文件上传接口")
    public ApiResult<UploadInfoVo> upload(@RequestPart("uploadFile") MultipartFile uploadFile) throws Exception {
        return ApiResult.ok();
    }

swagger中页面如下，调试页面的上传域已经出来了：

如果想要添加@ApiImplicitParam注解，经尝试，必须设置dataTypeClass才可以生效。代码如下：

    @PostMapping(value = "/upload")
    @ApiOperation(value = "文件上传接口", notes = "文件上传接口")
    @ApiImplicitParam(name = "uploadFile", value = "上传的文件", dataType = "_File", dataTypeClass = MultipartFile.class, required = true)
    public ApiResult<UploadInfoVo> upload(@RequestPart("uploadFile") MultipartFile uploadFile) throws Exception {
        return ApiResult.ok();
    }

swagger页面如下：

3 失败案例

以下为部分不生效的案例，以下案例中swagger的调试页面无任何参数信息：

    @PostMapping(value = "/upload", headers = "Content-Type=multipart/form-data")
    @ApiOperation(value = "文件上传接口", notes = "文件上传接口")
    public ApiResult<UploadInfoVo> upload(@RequestParam("uploadFile") MultipartFile uploadFile) throws Exception {
        return ApiResult.ok();
    }

    @PostMapping(value = "/upload", headers = "Content-Type=multipart/form-data")
    @ApiOperation(value = "文件上传接口", notes = "文件上传接口")
    @ApiImplicitParam(name = "uploadFile", value = "上传的文件", dataType = "_File", required = true, paramType = "query")
    public ApiResult<UploadInfoVo> upload(@RequestParam("uploadFile") MultipartFile uploadFile) throws Exception {
        return ApiResult.ok();
    }

    @PostMapping(value = "/upload")
    @ApiOperation(value = "文件上传接口", notes = "文件上传接口")
    @ApiImplicitParam(name = "uploadFile", value = "上传的文件", dataType = "_File", required = true, paramType = "query")
    public ApiResult<UploadInfoVo> upload(@RequestParam("uploadFile") MultipartFile uploadFile) throws Exception {
        return ApiResult.ok();
    }

以下案例虽然上传文件请求参数可以显示出来，但是不显示选择文件的按钮：

@PostMapping(value = "/upload", headers = "Content-Type=multipart/form-data", consumes = {MediaType.MULTIPART_FORM_DATA_VALUE})
    @ApiOperation(value = "文件上传接口", notes = "文件上传接口")
    @SysLog(value = "文件上传", type = LogTypeEnum.UPLOAD)
    @ApiImplicitParam(name = "uploadFile", value = "上传的文件", dataType = "File", required = true, paramType = "query")
    public ApiResult<UploadInfoVo> upload(@RequestPart("uploadFile") MultipartFile uploadFile) throws Exception {
        return ApiResult.ok();
    }