@Data
@AllArgsConstructor
@NoArgsConstructor
class Nation extends BaseSerializable {
    @JSONField(defaultValue = "汉族", name= "name")
    private String na_me;

    @JSONField(ordinal = 1, name = "DRESS")
    private String dress;

    @JSONField(ordinal = 3, format = "yyyy-MM-dd")
    private Date celebrateHoliday;
    @JSONField(ordinal = 2, name = "number")
    private Integer num;
}

Nation nationBean1 = Nation.builder().name("汉族").build();
String str = JSON.toJSONString(nationBean1);
System.out.println(str);