jackson json 日期格式轉換

Question

請幫助更改日期格式。

**來源** json 文件

**對象** 員工 Object

我需要支持將文件 json 日期轉換為 Object. 從文件

{
 "dateOfBirth": {
    "year": 1980,
    "month": "MAY",
    "monthValue": 5,
    "dayOfMonth": 4,
    "dayOfYear": 124,
    "dayOfWeek": "WEDNESDAY",
    "chronology": {
      "calendarType": "iso8601",
      "id": "ISO"
    },
    "era": "CE",
    "leapYear": false
  }
}

至 Object

{"dateOfBirth": "1980-05-04"}

Object

public class Employee {   
    private LocalDate dateOfBirth;
    //setter
    //getter
}

庫"com.fasterxml.jackson.datatype:jackson-datatype-jsr310"

日期： java.time.LocalDate

我的目標是從文件中讀取 json 數據和 map 到 object。

Answer 1

您可以使用自定義反序列化器。

public class EmployeeBirthDateDeserializer extends StdDeserializer<LocalDate> {

  public EmployeeBirthDateDeserializer() {
    super(LocalDate.class);
  }

  @Override
  public LocalDate deserialize(JsonParser parser, DeserializationContext context) throws IOException {
    JsonNode root = parser.getCodec().readTree(parser);
    return LocalDate.of(root.get("year").asInt(), root.get("monthValue").asInt(), root.get("dayOfMonth").asInt());
  }
}

然后使用@JsonDeserialize將它僅應用於Employee中的dateOfBirth字段：

public class Employee {

  @JsonDeserialize(using = EmployeeBirthDateDeserializer.class)
  private LocalDate dateOfBirth;

  //getters and setter
}

測試：

public class Temp {

  public static void main(String[] args) throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    Employee employee = mapper.readValue(ClassLoader.getSystemResourceAsStream("strange-date.json"), Employee.class);
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    System.out.println(formatter.format(employee.getDateOfBirth()));
  }
}

打印： 1980-05-04 。