前端和后端交互数据类型转换

页面是男/女 后端pojo类以及数据库中是Integer 0/1 怎么样很方便地转化?

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Person implements Serializable {
    private static final long serialVersionUID = 4346092911489022673L;

    private Integer id;
    private String name;
    private Integer age;

    /**
     * 1 男，0 女
     */
    private Integer gender;

    @JsonDeserialize(using = GenderJsonDeserializer.class)
    public void setGender(Integer gender) {
        this.gender = gender;
    }

    @JsonSerialize(using = GenderJsonSerializer.class)
    public Integer getGender() {
        return gender;
    }
}

@Component
@Slf4j
public class GenderJsonDeserializer extends JsonDeserializer {

    @Override
    public Integer deserialize(JsonParser p, DeserializationContext ctxt)
            throws IOException, JsonProcessingException {
            
        if (ObjectUtils.isEmpty(p)) {
            return null;
        }

        int gender = 0;

        switch (p.getText()) {
            case "男":
                gender = 1;
                break;
            case "女":
                break;
            default:
                throw new RuntimeException("传入的性别为非法字符！");
        }

        log.info("【 GenderJsonDeserializer.deserialize() 】  p.getText() ==> " 
                        + p.getText() + "，转换后的结果 ==> " + gender);

        return gender;
    }
}

@Component
@Slf4j
public class GenderJsonSerializer extends JsonSerializer {
    @Override
    public void serialize(Object value, JsonGenerator gen, SerializerProvider serializers) 
            throws IOException {
            
        log.info("【 GenderJsonSerializer.serialize() 】  value ==> " + value);
        if (value.equals(1)) {
            gen.writeString("男");
        } else if (value.equals(0)) {
            gen.writeString("女");
        }
    }
}

----枚举转化--

在web开发中有时会使用枚举作为参数，而前端在调接口时就会出现传错或者传空导致后端拿不到枚举类型。在这里就使用反序列化@JsonDeserialize

这里是对枚举进行反序列化，所以首先编写一个类

public class EnumDeserializer extends JsonDeserializer<Enum<?>> {

@Override
 public Enum<?> deserialize(JsonParser jp, DeserializationContext cxt) throws IOException {
     String value = jp.getValueAsString();
     if (StringUtils.isBlank(value))
         return null;
     Class findPropertyType = BeanUtils.findPropertyType(jp.currentName(), jp.getCurrentValue().getClass());
     try {
         return Enum.valueOf(findPropertyType, value);
     } catch (IllegalArgumentException e) {
         return null;
     }
 }

}

该类会判断前端传入的数据的某个字段是否能够解析为枚举，如果不能则返回null。
最后在传入的请求类的枚举字段上加入@JsonDeserialize注解

@JsonDeserialize(using = EnumDeserializer.class)
 private EventEnum event;

而之后又遇到了数组枚举，那么在反序列化的时候的问题就主要是要拿到数组的泛型类，而通过反射可以做到这一点。

public class ListEnumDeserializer extends JsonDeserializer<List<Enum<?>>> { @Override public List<Enum<?>> deserialize(JsonParser jp, DeserializationContext cxt) throws IOException {
ArrayNode treeNode = jp.readValueAsTree();
Field field;
try {
field = jp.getCurrentValue().getClass().getDeclaredField(jp.currentName());
} catch (NoSuchFieldException e) {
return null;
}
field.setAccessible(true);
if (!field.getType().equals(List.class)) {
return null;
}
ParameterizedType genericType = (ParameterizedType) field.getGenericType();
Class actualTypeArgument = (Class) genericType.getActualTypeArguments()[0];
List<Enum<?>> result = new ArrayList<>();
Iterator<JsonNode> elements = treeNode.elements();
while (elements.hasNext()) {
String appCase = elements.next().asText();
try {
Enum anEnum = Enum.valueOf(actualTypeArgument, appCase);
result.add(anEnum);
} catch (IllegalArgumentException e) {
continue;
}
}
if (result.isEmpty()) {
return null;
} else {
return result;
}
}
}

同样在最后字段上加入注解

@JsonDeserialize(using = ListEnumDeserializer.class)
 private List<AppCaseEnum> appCase;