Spring Boot项目如何优雅实现Excel导入与导出功能

<dependency>
    <groupId>com.zzuhkp</groupId>
    <artifactId>easyexcel-spring-boot-starter</artifactId>
    <version>1.0-SNAPSHOT</version>
</dependency>

@Data
public class DemoData {
    @ExcelProperty(index = 0)
    private Integer integer;

    @ExcelProperty(index = 1)
    private String string;

    @ExcelProperty(index = 2)
    private Date date;
}

@PostMapping("/list/obj")
public List<DemoData> listObj(@ExcelParam List<DemoData> list) {
    return list;
}

@ExcelParam(value = "file", required = true)

@PostMapping("/list/rows")
public ReadRows<DemoData> readRows(@ExcelParam ReadRows<DemoData> readRows) {
    return readRows;
}

public class ReadRows<T> {

    private ExcelReadHeadProperty excelReadHeadProperty;

    private List<ReadRow<T>> rows;
}

public class ReadRow<T> {

    // 行索引，从 0 开始
    private final Integer rowIndex;

    // 行记录对应对象
    private final T data;
}

// 对象字段名称 -> 从 0 开始的列索引
Map<String, Integer> fieldColumnIndexMap = readRows.getExcelReadHeadProperty().getHeadMap().values()
        .stream().collect(Collectors.toMap(Head::getFieldName, Head::getColumnIndex));

@ExcelResponse
@GetMapping("/list/download")
public List<DemoData> downloadList() {
    return Arrays.asList(new DemoData(1, "hello", new Date()), new DemoData(2, "excel", new Date()));
}

@ExcelResponse(fileName = "测试文件", sheetName = "工作表1")

@PostMapping("/list/obj")
public List<DemoData> listObj(@ExcelParam @Validated List<DemoData> list) {
    return list;
}

@Data
public class DemoData {
    @NotNull(message = "参数不能为空")
    private Integer integer;

    private String string;

    private Date date;
}

... 省略其他元注解
@Constraint(validatedBy = {DemoDataValid.DemoDataValidator.class})
public @interface DemoDataValid {
		... 省略注解属性
		
    class DemoDataValidator implements ConstraintValidator<DemoDataValid, DemoData> {

        @Override
        public boolean isValid(DemoData value, ConstraintValidatorContext context) {
            context.disableDefaultConstraintViolation();
            context.buildConstraintViolationWithTemplate("测试对象校验").addConstraintViolation();
            return false;
        }
    }
}

@DemoDataValid
public class DemoData {
    ... 省略属性
}

public interface ExcelValidator<T> {
    ExcelValidErrors validate(ReadRows<T> readRows);
}

public class ExcelValidErrors {
	// 行错误信息或单元格错误信息列表
    private final List<ExcelValidObjectError> errors;
}

public interface ExcelValidObjectError {
    // 获取行号，从 1 开始
    Integer getRow();

    // 获取错误消息
    String getMessage();
}

public interface ExcelValidFieldError extends ExcelValidObjectError {
    // 获取列，从 1 开始
    Integer getColumn();
}

@Component
public class CustomExcelValidator implements ExcelValidator<DemoData> {
    @Override
    public ExcelValidErrors validate(ReadRows<DemoData> readRows) {
        ExcelValidErrors errors = new ExcelValidErrors();

        Map<Integer, List<ReadRow<DemoData>>> group = readRows.getRows().stream()
                .collect(Collectors.groupingBy(item -> item.getData().getInteger()));

        for (Map.Entry<Integer, List<ReadRow<DemoData>>> entry : group.entrySet()) {
            if (entry.getValue().size() > 1) {
                for (ReadRow<DemoData> readRow : entry.getValue()) {
                    errors.addError(new DefaultExcelObjectError(readRow.getRowIndex() + 1, "参数重复"));
                }
            }
        }
        return errors;
    }
}

@RestControllerAdvice
public class GlobalExceptionControllerAdvice {
    @ExceptionHandler(ExcelValidException.class)
    public String handleException(ExcelValidException e) {
        ExcelValidErrors errors = e.getErrors();
        return JSON.toJSONString(errors);
    }
}

@PostMapping("/list/obj")
public List<DemoData> listObj(@ExcelParam @Validated List<DemoData> list, ExcelValidErrors errors) {
    if (errors.hasErrors()) {
        String messages = errors.getAllErrors().stream().map(ExcelValidObjectError::getMessage).collect(Collectors.joining(" | "));
        throw new RuntimeException("发现异常:" + messages);
    }
    return list;
}