spring boot项目同时传递参数和文件的多种方式

在开发接口中，遇到了需要同时接收参数和文件的情况，可以有多种方式实现文件+参数的接收，这里基于spring boot 3 + vue 3 + axios，做一个简单的代码演示。

1 简单参数 + 文件参数

参数较少时，比较方便，直接参数接受即可

1.1 后端接口

@RestController
@RequestMapping("/param")
@Validated
public class FileParamController extends BaseController {
    /**
     * 简单参数
     *
     * @param test1
     * @param test2
     * @param file
     * @return
     */
    @PostMapping("/file-simple-param")
    public Map<String, Object> fileAndSimpleParam(@RequestParam @NotBlank String test1,
                                                  @RequestParam @NotBlank String test2,
                                                  @RequestParam MultipartFile file) {
        Map<String, Object> objectMap = new HashMap<>();
        objectMap.put("test1", test1);
        objectMap.put("test2", test2);
        objectMap.put("fileName", file.getOriginalFilename());
        return objectMap;
    }
}

1.2 前端请求

const fileAndSimpleParamFuc = (methodParam: { file: string | Blob }) => {
	let formData = new FormData()
	formData.append('test1', 'test1')
	formData.append('test2', 'test2')
	formData.append('file', methodParam.file)
	fileAndSimpleParam(formData).then(resp => {
		console.log(resp)
	})
}

fileAndSimpleParam 为封装的api请求方法，可查看下文的 param.ts

2 简单参数转JavaBean + 文件参数

将各个参数封装到一个JavaBean中接收，同时接收文件参数，此时JavaBean参数不加任何注解，不支持接收List参数

2.1 后端接口

@RestController
@RequestMapping("/param")
@Validated
public class FileParamController extends BaseController {
    /**
     * 简单参数转JavaBean接收，不支持如：LIst<xxx> 这样的属性
     *
     * @param bean
     * @param file
     * @return
     */
    @PostMapping("/file-simple-bean")
    public SimpleBean fileAndSimpleJavaBean(@Validated SimpleBean bean, @RequestParam MultipartFile file) {
        bean.setFileName(file.getOriginalFilename());
        return bean;
    }
}

SimpleBean.java

@Data
public class SimpleBean {
    @NotBlank
    private String test1;

    @NotBlank
    private String test2;
    
    @Null(message = "The fileName is not support to be used")
    private String fileName;
}

2.2 前端请求

const fileAndSimpleJavaBeanFuc = (methodParam: { file: string | Blob }) => {
	let formData = new FormData()
	formData.append('test1', 'test1')
	formData.append('test2', 'test2')
	formData.append('file', methodParam.file)
	fileAndSimpleJavaBean(formData).then(resp => {
		console.log(resp)
	})
}

fileAndSimpleJavaBean 为封装的api请求方法，可查看下文的 param.ts

3 简单参数转String + 文件参数

在这种接收方式中，使用String来接收参数，在使用工具（如fastjson）手动转为JavaBean，支持接收List参数，但是需要自行校验参数是否满足要求

3.1 后端接口

@RestController
@RequestMapping("/param")
@Validated
public class FileParamController extends BaseController {
    /**
     * 参数转字符串接收，支持复杂参数属性，如：List<xxx>
     *
     * @param bean
     * @param file
     * @return
     */
    @PostMapping("/file-and-json")
    public SimpleBean fileAndJsonJavaBean(String bean, @RequestParam MultipartFile file) {
        SimpleBean simpleBean = JSON.parseObject(bean, SimpleBean.class);
        //自定义参数校验
        List<String> valid = ValidatorUtils.validFast(simpleBean);
        if (!valid.isEmpty()) {
            throw new FailException(String.join(",", valid));
        }
        simpleBean.setFileName(file.getOriginalFilename());
        return simpleBean;
    }
}

SimpleBean.java

@Data
public class SimpleBean {
    @NotBlank
    private String test1;

    @NotBlank
    private String test2;

    private List<ParamBO> params;

    @Null(message = "The fileName is not support to be used")
    private String fileName;
}

ValidatorUtils.java

借助spring的参数校验做自定义调用

public class ValidatorUtils {
    private static final Validator VALIDATOR_FAST = Validation.byProvider(HibernateValidator.class).configure().failFast(true).buildValidatorFactory().getValidator();
    private static final Validator VALIDATOR_ALL = Validation.byProvider(HibernateValidator.class).configure().failFast(false).buildValidatorFactory().getValidator();

    private ValidatorUtils(){}

    /**
     * 参数校验，遇到第一个不合法的字段直接返回不合法字段，后续字段不再校验
     *
     * @param object
     * @return
     * @param <T>
     */
    public static <T> List<String> validFast(T object, Class<?>... groups){
        return valid(VALIDATOR_FAST, object, groups);
    }

    /**
     * 校验所有字段并返回不合法字段
     *
     * @param object
     * @return
     * @param <T>
     */
    public static <T> List<String> validAll(T object, Class<?>... groups){
        return valid(VALIDATOR_ALL, object, groups);
    }

    private static <T> List<String> valid(Validator validator, T object, Class<?>... groups){
        Set<ConstraintViolation<T>> errors = validator.validate(object, groups);
        return errors.stream().map(ConstraintViolation::getMessage).toList();
    }
}

3.2 前端请求

const fileAndJsonStringToJavaBeanFuc = (methodParam: { file: string | Blob }) => {
	let paramList = []
	for (let i = 0; i < 3; i++) {
		let param = { username: '参数' + i, data: '参数值' + i }
		paramList.push(param)
	}
	let data = {
		test1: 'test1',
		test2: 'test2',
		params: paramList
	}
	let formData = new FormData()
	formData.append('bean', JSON.stringify(data))
	formData.append('file', methodParam.file)
	fileAndJsonStringToJavaBean(formData).then(resp => {
		console.log(resp)
	})
}

fileAndJsonStringToJavaBean 为封装的api请求方法，可查看下文的 param.ts

4 文件放入JavaBean接收

将文件作为JavaBean的属性，随参数一起接收

4.1 后端接口

@RestController
@RequestMapping("/param")
@Validated
public class FileParamController extends BaseController {
    /**
     * 文件放入JavaBean一起提交
     *
     * @param bean
     * @return
     */
    @PostMapping(value = "/file-in-bean")
    public String fileInJavaBean(@Validated FileInBeanBO bean) {
        bean.setFileName(bean.getFile().getOriginalFilename());
        return bean.getFile().getOriginalFilename();
    }
}

FileInBeanBO.java

@Data
public class SimpleBean {
    @NotBlank
    private String test1;

    @NotBlank
    private String test2;

    @Null(message = "The fileName is not support to be used")
    private String fileName;

    private MultipartFile file;
}

4.2 前端请求

此处需要特别注意，需要修改Content-Type

const fileInJavaBeanFuc = (methodParam: { file: string | Blob }) => {
	let formData = new FormData()
	formData.append('test1', 'test1')
	formData.append('test2', 'test2')
	formData.append('file', methodParam.file)
	fileInJavaBean(formData).then(resp => {
		console.log(resp)
	})
}

fileInJavaBean 为封装的api请求方法，可查看下文的 param.ts

5 文件和参数分别接收，@RequestPart注解

使用@RequestPart注解，实现参数与文件分别接收，应该来说是最优解，优先推荐

5.1 后端接口

@RestController
@RequestMapping("/param")
@Validated
public class FileParamController extends BaseController {
    /**
     * 参数与文件分开接收，支持复杂参数属性，如：List<xxx>
     *
     * @param bean
     * @param file
     * @return
     */
    @PostMapping("/file-and-bean")
    public FileBeanBO fileAndJavaBean(@RequestPart @Validated FileBeanBO bean, @RequestPart MultipartFile[] file) {
        String collect = Arrays.stream(file).map(MultipartFile::getOriginalFilename).collect(Collectors.joining(","));
        bean.setFileName(collect);
        return bean;
    }
}

FileBeanBO.java

@Data
public class SimpleBean {
    @NotBlank
    private String username;

    @Valid
    @NotEmpty
    private List<ParamBO> params;

    @Null(message = "The fileName is not support to be used")
    private String fileName;
    
    @Data
    public class ParamBO {
        private String username;
        private Object data;
    }
}

5.2 前端请求

此处需要特别注意，需要手动指定JavaBean的类型 Content-Type

const fileAndJavaBeanFuc = (methodParam: { file: string | Blob }) => {
	let formData = new FormData()
	let paramList = []
	for (let i = 0; i < 3; i++) {
		let param = { username: '参数' + i, data: '参数值' + i }
		paramList.push(param)
	}
	let data = {
		username: '张三',
		params: paramList
	}
	formData.append('bean', new Blob([JSON.stringify(data)], { type: 'application/json' }))
	formData.append('file', methodParam.file)
	fileAndJavaBean(formData).then(resp => {
		console.log(resp)
	})
}

fileAndJavaBean 为封装的api请求方法，可查看下文的 param.ts

6 前端封装 param.ts

export const fileAndSimpleParam = (params: any) => {
	return axios.post('/param/file-simple-param', params)
}

export const fileAndSimpleJavaBean = (params: any) => {
	return axios.post('/param/file-simple-bean', params)
}

export const fileAndJsonStringToJavaBean = (params: any) => {
	return axios.post('/param/file-and-json', params)
}

export const fileInJavaBean = (params: any) => {
	return axios.post('/param/file-in-bean', params, {
		headers: {
			'Content-Type': 'multipart/form-data'
		}
	})
}

export const fileAndJavaBean = (params: any) => {
	return axios.post('/param/file-and-bean', params)
}

7 后记

以上5种方式，都能实现参数与文件同时接受，至于使用哪一种，看具体需求，参数太多的时候，可以优先考虑@RequestPart注解。