java - 将 json 数组值反序列化为特定的 Java 类字段

Question

我有以下 Json

    {
    "coreId" : "1",
    "name" : "name",
    "additionalValueList" : [
      {
       "columnName" : "allow_duplicate",
       "rowId"  : "10",
       "value" :  "1"
      },
      {
       "columnName" : "include_in_display",
       "rowId"  : "11",
       "value" :  "0"
      },
      ...e.t.c
     ]
 },
 ...e.t.c

和Java类

class DTO {
@JsonProperty("coreId")
private Integer id;

private String name;

private Boolean allowDuplicate;

private Boolean includeInDisplay;
}

如何轻松地将“additionalValueList”中的值映射到相应的 java 字段。例如，字段“columnName”中的 Json 值 -“allow_duplicate”= DTO.allowDuplicate。实际上，我知道如何使用带有 @JsonDeserialize 注释和类似内容的自定义反序列化器来完成此操作。但是我有 40 多个 DTO，为每个字段创建自己的反序列化器并不是一个好主意。我正在寻找具有例如 1 个反序列化器的解决方案(因为“additionalValueList”中的值结构对于所有实体都相同)并将参数(我想要映射到该字段的字段名称)传递给将在“中找到的自定义反序列化器”具有“列名称”=参数(我从注释传递的)的“additionalValueList”实体并返回“值”。示例

class DTO {
@JsonProperty("coreId")
private Integer id;

private String name;

@JsonDeserialize(using = MyCustDeser.class,param = allow_duplicate)
private Boolean allowDuplicate;

@JsonDeserialize(using = MyCustDeser.class,param = include_in_display)
private Boolean includeInDisplay;
}

这将是一个很好的解决方案，但可能不容易实现。但是，我将非常感谢您的所有建议。谢谢。

Answer 1

创建 Converter类，然后在 DTO 类上指定它。

以下代码使用 public 字段来简化示例。

/**
 * Intermediate object used for deserializing FooDto from JSON.
 */
public final class FooJson {

    /**
     * Converter used when deserializing FooDto from JSON.
     */
    public static final class ToDtoConverter extends StdConverter<FooJson, FooDto> {
        @Override
        public FooDto convert(FooJson json) {
            FooDto dto = new FooDto();
            dto.name = json.name;
            dto.id = json.coreId;
            dto.allowDuplicate = lookupBoolean(json, "allow_duplicate");
            dto.includeInDisplay = lookupBoolean(json, "include_in_display");
            return dto;
        }
        private static Boolean lookupBoolean(FooJson json, String columnName) {
            String value = lookup(json, columnName);
            return (value == null ? null : (Boolean) ! value.equals("0"));
        }
        private static String lookup(FooJson json, String columnName) {
            if (json.additionalValueList != null)
                for (FooJson.Additional additional : json.additionalValueList)
                    if (columnName.equals(additional.columnName))
                        return additional.value;
            return null;
        }
    }

    public static final class Additional {
        public String columnName;
        public String rowId;
        public String value;
    }

    public Integer coreId;
    public String name;
    public List<Additional> additionalValueList;
}

您现在只需注释 DTO 即可使用它:

@JsonDeserialize(converter = FooJson.ToDtoConverter.class)
public final class FooDto {
    public Integer id;
    public String name;
    public Boolean allowDuplicate;
    public Boolean includeInDisplay;

    @Override
    public String toString() {
        return "FooDto[id=" + this.id +
                    ", name=" + this.name +
                    ", allowDuplicate=" + this.allowDuplicate +
                    ", includeInDisplay=" + this.includeInDisplay + "]";
    }
}

测试

ObjectMapper mapper = new ObjectMapper();
FooDto foo = mapper.readValue(new File("test.json"), FooDto.class);
System.out.println(foo);

输出

FooDto[id=1, name=name, allowDuplicate=true, includeInDisplay=false]