1：如果單獨的只有實體對象，對象里面沒有MultipartFile屬性

1-1：DTO對象

@Slf4j
@Data
public class PaperFileDTO {
    private String paperFileName;
    private Integer auditTypeId;
    private String studyType;
    private Integer studyTypeId;
    private Integer paperDuration;
    private String joinNumber;
    private String paperAttention;
    private String[] paperTime;
}

1-2：第一種方法：springMVC接受參數@RequestBody

@PostMapping(value = "/upload/document")
public Result<String> uploadFile( @RequestBody PaperFileDTO paperFileDTO) {
        MultipartFile file=null;
        String result = sysStudyPaperFileService.uploadFile(paperFileDTO,file);
        return Result.OK(result);
    }

1-3：第二種方法：springMVC接受參數

@PostMapping(value = "/upload/document")
public Result<String> uploadFile( PaperFileDTO paperFileDTO) {
        MultipartFile file=null;
        String result = sysStudyPaperFileService.uploadFile(paperFileDTO,file);
        return Result.OK(result);
    }

2：第一種接受方法：前端傳送過來有對象和MultipartFile

2-1：DTO對象

@Slf4j
@Data
public class PaperFileDTO {
    private String paperFileName;
    private Integer auditTypeId;
    private String studyType;
    private Integer studyTypeId;
    private Integer paperDuration;
    private String joinNumber;
    private String paperAttention;
    private String[] paperTime;
    private MultipartFile file;
}

2-2：MultipartFile 封裝在對象里，就不能使用@RequestBody接受springMVC參數，只能這樣接收

public Result<String> uploadFile(PaperFileDTO paperFileDTO) {
        MultipartFile file=null;
        String result = sysStudyPaperFileService.uploadFile(paperFileDTO,file);
        return Result.OK(result);
    }

3：第二種接受方法：前端傳送過來有對象和MultipartFile

2-1：DTO對象

@Slf4j
@Data
public class PaperFileDTO {
    private String paperFileName;
    private Integer auditTypeId;
    private String studyType;
    private Integer studyTypeId;
    private Integer paperDuration;
    private String joinNumber;
    private String paperAttention;
    private String[] paperTime;
}

2-2：MultipartFile 不封裝在對象里，這樣接收

public Result<String> uploadFile(  PaperFileDTO paperFileDTO,@RequestBody MultipartFile file) {
        String result = sysStudyPaperFileService.uploadFile(paperFileDTO,file);
        return Result.OK(result);
    }

前端必須使用multipart 和form-data

3：接受MultipartFile接受參數必須和前端傳參一致或者用@RequestParam(“file”)指定

public Result<String> uploadFile(  PaperFileDTO paperFileDTO,@RequestParam("file") MultipartFile multipartFile ) {
        String result = sysStudyPaperFileService.uploadFile(paperFileDTO,multipartFile );
        return Result.OK(result);
    }

4：多文件上傳用MultipartFile[] 接受

public Result<String> uploadFile( @RequestBody MultipartFile[] multipartFile ) {
		for (int i = 0; i < multipartFile.length ; i++) {
            sysStudyPaperFileService.uploadFile(multipartFile[i] );
        }
        
        return Result.OK("上傳完成");
    }

5：不可以這樣傳參，只能會有一個傳參成功paperFile或者file：

@Data
public class PaperFileDTO {
    private PaperFile paperFile;
    private MultipartFile file;
}