enum json convert

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java里，enum类型跟json的互相转换，以及利用orm库doma2时的转换

enum和实用类

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@RequiredArgsConstructor
@Getter
public enum ReportType {
    OPPORTUNITY("01", "合同"),
    PARKING_LOT("02", "车库"),
    COMPANY("03", "公司");

    private final String value;
    private final String name;
}
@Data
@AllArgsConstructor
public class Report{
    private Integer reportId;
    private ReprortType reprortType;
}

enum->json

使用@JsonValue，可以在转换为json时输出赋予的字段

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@RequiredArgsConstructor
@Getter
public enum ReportType {
    OPPORTUNITY("01", "合同"),
    PARKING_LOT("02", "车库"),
    COMPANY("03", "公司");

    @JsonValue
    private final String value;
    private final String name;
}

下面这个实例

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new Reprot(1, ReportType.PARKING_LOT);

输出为

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{"reportId":1, "reprortType":"02"}

使用@JsonFormat，可以把enum作为整体输出

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@RequiredArgsConstructor
@Getter
@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum ReportType {
    OPPORTUNITY("01", "合同"),
    PARKING_LOT("02", "车库"),
    COMPANY("03", "公司");

    private final String value;
    private final String name;
}

下面这个实例

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new Reprot(1, ReportType.PARKING_LOT);

输出为

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{"reportId":1, "reprortType":{"value":"02", "name":"车库"}}

自定义Serializer

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public class ReportSerializer extends StdSerializer<ReportType> {
    public ReportSerializer() {
        super(ReportType.class);
    }

    @Override
    public void serialize(ReportType reportType, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeStartObject();
        gen.writeFieldName("value");
        gen.writeString(reportType.getValue());
        gen.writeFieldName("name");
        gen.writeString(reportType.getName());
        gen.writeEndObject();
    }
}

制定一个Module

如果类似的enum比较多，可以定义一个interface

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public interface Enumerator {
    String getValue();
    String getName;
}

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@RequiredArgsConstructor
@Getter
public enum ReportType implements Enumerator{
    OPPORTUNITY("01", "合同"),
    PARKING_LOT("02", "车库"),
    COMPANY("03", "公司");

    private final String value;
    private final String name;
}

然后制定一个Module，注册到spring里

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@Bean
public Jackson2ObjectMapperBuilderCustomizer enumCustomizer(){
    return jacksonObjectMapperBuilder -> jacksonObjectMapperBuilder.serializerByType(Enumerator.class, new JsonSerializer<Enumerator>() {
        @Override
        public void serialize(Enumerator value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
                    gen.writeStartObject();
                    gen.writeStringField("code",value.getValue());
                    gen.writeStringField("description",value.getName());
                    gen.writeEndObject();


        }
    });
}

json->enum

使用@JsonValue，使用指定字段构建enum

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{"reportId":1, "reprortType":"02"}

转换为

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new Reprot(1, ReportType.PARKING_LOT);

使用JsonCreator，自定义创建发方法

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@RequiredArgsConstructor
@Getter
public enum ReportType {
    OPPORTUNITY("01", "合同"),
    PARKING_LOT("02", "车库"),
    COMPANY("03", "公司");

    private final String value;
    private final String name;

    @JsonCreator(mode = JsonCreator.Mode.DELEGATING)
    public static ReportType of(String value) {
        for (ReportType reportType : ReportType.values()) {
            if (reportType.value.equals(value)) {
                return reportType;
            }
        }
        throw new IllegalArgumentException(value);
    }
}

根据需求自由组合

一般项目会根据前端用关键字段进行json<->enum的转换，所以使用@JsonValue最为方便。
另外如果在输出的时候，有特殊要求，可以用自定义Serializer的形式进行注解
结合doma2的使用，最终的形式为：

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@Domain(valueType = String.class, factoryMethod = "of")
@RequiredArgsConstructor
@Getter
public enum ReportType {
    OPPORTUNITY("01", "合同"),
    PARKING_LOT("02", "车库"),
    COMPANY("03", "公司");

    @JsonValue
    private final String value;
    private final String name;

    public static ReportType of(String value) {
        for (ReportType reportType : ReportType.values()) {
            if (reportType.value.equals(value)) {
                return reportType;
            }
        }
        throw new IllegalArgumentException(value);
    }

    public static List<ReportType> getAll() {
        return List.of(ReportType.values());
    }
}

public class ReportSerializer extends StdSerializer<ReportType> {
    public ReportSerializer() {
        super(ReportType.class);
    }

    @Override
    public void serialize(ReportType reportType, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeStartObject();
        gen.writeFieldName("value");
        gen.writeString(reportType.getValue());
        gen.writeFieldName("name");
        gen.writeString(reportType.getName());
        gen.writeEndObject();
    }
}

使用

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@Data
public class Report{
    private Integer reportId;
    private ReprortType reprortType;
}

@Data
public class ReportDefinition{
    @JsonSerialize(contentUsing = ReportSerializer.class)
    private List<ReprortType> reprortType;
}