编写一个简单的EasyExcel枚举类转换器

最近项目中用到了阿里的EasyExcel，一个简单方便读写excel的工具。

需求场景

在项目中会定义一些枚举类来保存一些状态值，在存储进数据库时保存的是code,而我们在生成excel时需要展示对应的值。

代码实现

原

需要写入excel的对象

@Data
public class TestExcel {

    /**
     * 状态
     */
    @ExcelProperty(value = "状态",converter = StatusEnumConvert.class)
    private String status;
}

枚举类

public enum StatusEnum {
    WAIT_COMMIT("1","待提交"),
    WAIT_AUDIT("2","待审核"),
    AUDITED("3","已审核"),
    RETURNED("4","已退回");

    private final String code;
    private final String info;

    StatusEnum(String code, String info)
    {
        this.code = code;
        this.info = info;
    }

    public String getCode()
    {
        return code;
    }

    public String getInfo()
    {
        return info;
    }

    /**
     * 根据code获取info
     */
    public static String getInfoByCode(String code){
        for (StatusEnum statusEnum : StatusEnum.values()) {
            if (statusEnum.getCode().equals(code)){
                return statusEnum.getInfo();
            }
        }
        return null;
    }

    public static String getCodeByInfo(String info){
        for (StatusEnum statusEnum : StatusEnum.values()) {
            if (statusEnum.getInfo().equals(info)){
                return statusEnum.getCode();
            }
        }
        return null;
    }
}

转换器

public class StatusEnumConvert implements Converter<String> {

    @Override
    public Class supportJavaTypeKey() {
        return String.class;
    }

    @Override
    public CellDataTypeEnum supportExcelTypeKey() {
        return CellDataTypeEnum.STRING;
    }

    @Override
    public String convertToJavaData(CellData cellData, ExcelContentProperty excelContentProperty, GlobalConfiguration globalConfiguration) throws Exception {
        String info = cellData.toString();
        return StatusEnum.getCodeByInfo(info);
    }

    @Override
    public CellData convertToExcelData(String s, ExcelContentProperty excelContentProperty, GlobalConfiguration globalConfiguration) throws Exception {
        return new CellData(Objects.requireNonNull(StatusEnum.getInfoByCode(s)));
    }
}

---

应网友反馈，使用注解和反射改进了转换器，提高复用性；

改进后

先自定义一个注解

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface TargetEnum {
    Class<? extends Enum> targetEnum();
}

需要转换的枚举类

不再需要getCodeByInfo()与getInfoById()方法

public enum StatusEnum implements GetEnum {
    WAIT_COMMIT("1","待提交"),
    WAIT_AUDIT("2","待审核"),
    AUDITED("3","已审核"),
    RETURNED("4","已退回");

    private final String code;
    private final String info;

    StatusEnum(String code, String info)
    {
        this.code = code;
        this.info = info;
    }

    public String getCode()
    {
        return code;
    }

    public String getInfo()
    {
        return info;
    }
}

需要写入excel的对象

@Data
public class TestExcel {
    //加上自定义注解，并写上对应的枚举类作为参数
    @TargetEnum(targetEnum = StatusEnum.class)
    @ExcelProperty(value = "状态",converter = StatusEnumConverter.class)
    private String status;
}

修改后的转换器

利用反射获取字段上注解的枚举类型，然后调用get..()方法取值

public class StatusEnumConverter implements Converter<String> {
    @Override
    public Class supportJavaTypeKey() {
        return String.class;
    }

    @Override
    public CellDataTypeEnum supportExcelTypeKey() {
        return CellDataTypeEnum.STRING;
    }

    @Override
    public String convertToJavaData(CellData cellData, ExcelContentProperty excelContentProperty, GlobalConfiguration globalConfiguration) throws Exception {
        String code="";
        String info = cellData.toString();
        Field field = excelContentProperty.getField();
        TargetEnum annotation = field.getDeclaredAnnotation(TargetEnum.class);
        Class clazz = annotation.targetEnum();
        Object[] enumConstants = clazz.getEnumConstants();
        Method getInfo = clazz.getMethod("getInfo");
        Method getCode = clazz.getMethod("getCode");
        for (Object enumConstant : enumConstants) {
            if (getInfo.invoke(enumConstant, null).equals(info)) {
                code = (String) getCode.invoke(enumConstant, null);
                break;
            }
        }
        return code;
    }

    @Override
    public CellData convertToExcelData(String s, ExcelContentProperty excelContentProperty, GlobalConfiguration globalConfiguration) throws Exception {
        String info = "";
        Field field = excelContentProperty.getField();
        TargetEnum annotation = field.getDeclaredAnnotation(TargetEnum.class);
        Class clazz = annotation.targetEnum();
        Object[] enumConstants = clazz.getEnumConstants();
        Method getInfo = clazz.getMethod("getInfo");
        Method getCode = clazz.getMethod("getCode");
        for (Object enumConstant : enumConstants) {
            if (getCode.invoke(enumConstant, null).equals(s)) {
                info = (String) getInfo.invoke(enumConstant, null);
                break;
            }
        }
        return new CellData(info);
    }
}

调用

EasyExcel.write(filePath,TestExcel.class).sheet("枚举转换器").doWrite(dataList());

效果