问题描述
当我在嵌套字段上使用@JsonUnwrapped
时:
When I use @JsonUnwrapped
on nested field:
public class Person{
private int id;
@JsonUnwrapped
private Father father
//getters/setters
@Data
@AllArgsConstructor
private static class Father {
private String name;
private String surname;
}
同时使用@JsonCreator
:
@JsonCreator // DESERIALIZATION: JSON -> POJO
public Person(...
@JsonProperty("name") String name,
@JsonProperty("surname") String surname) {
(...)
this.father = new Father(name, surname);
,其中Father
是嵌套类.
我得到了错误:
Father` (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creat
但是当我删除@JsonUnwrapped
时,该字段可以反序列化,但是在序列化期间不会变平.How to assure that Father field will be serialised and deserialised flatten at the same time?
But when I remove the @JsonUnwrapped
the field gets deserialised ok but is not flatten during serialisation. How to assure that Father field will be serialised and deserialised flatten at the same time?
我粘贴完整的代码:
@Data
@JsonIgnoreProperties(ignoreUnknown = true)
public class Person {
private int id;
private String firstName;
private String lastName;
private boolean active;
private Address address;
private String[] languages;
@JsonIgnore private boolean isTheKing;
@JsonUnwrapped // SERIALIZATIONL POJO -> JSON
private Father father;
@JsonCreator // DESERIALIZATION: JSON -> POJO
public Student(
@JsonProperty("id") int id,
@JsonProperty("firstName") String firstName,
@JsonProperty("lastName") String lastName,
@JsonProperty("active") boolean active,
@JsonProperty("address") Address address,
@JsonProperty("languages") String[] languages,
@JsonProperty("isTheKing") boolean isTheKing,
@JsonProperty("name") String name,
@JsonProperty("surname") String surname) {
this.id = id;
this.firstName = firstName;
this.lastName = lastName;
this.active = active;
this.address = address;
this.languages = languages;
this.isTheKing = isTheKing;
this.father = new Father(name, surname);
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public boolean isActive() {
return active;
}
public void setActive(boolean active) {
this.active = active;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public String[] getLanguages() {
return languages;
}
public void setLanguages(String[] languages) {
this.languages = languages;
}
public Father getFather() {
return father;
}
public void setFather(Father father) {
this.father = father;
}
@Data
@AllArgsConstructor
static class Father {
private String name;
private String surname;
}
}
以下主要方法失败:
ObjectMapper mapper = new ObjectMapper();
Person myStudent =
mapper.readValue(new File("src/main/resources/data/rest/studentIN.json"), Person.class);
System.out.println(myStudent);
有错误:
我用龙目岛:
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.6</version>
</dependency>
推荐答案
它应该适用于简单的POJO
模型. Father
类应为public
:
It should work for simple POJO
model. Father
class should be public
:
import com.fasterxml.jackson.annotation.JsonUnwrapped;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
public class JsonApp {
public static void main(String[] args) throws Exception {
ObjectMapper mapper = new ObjectMapper();
mapper.enable(SerializationFeature.INDENT_OUTPUT);
Person.Father father = new Person.Father();
father.setName("Wit");
father.setSurname("Pil");
Person person = new Person();
person.setId(1909);
person.setFather(father);
String json = mapper.writeValueAsString(person);
System.out.println(json);
System.out.println(mapper.readValue(json, Person.class));
}
}
class Person {
private int id;
@JsonUnwrapped
private Father father;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public Father getFather() {
return father;
}
public void setFather(Father father) {
this.father = father;
}
@Override
public String toString() {
return "Person{" +
"id=" + id +
", father=" + father +
'}';
}
static class Father {
private String name;
private String surname;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSurname() {
return surname;
}
public void setSurname(String surname) {
this.surname = surname;
}
@Override
public String toString() {
return "Father{" +
"name='" + name + '\'' +
", surname='" + surname + '\'' +
'}';
}
}
}
上面的代码显示:
{
"id" : 1909,
"name" : "Wit",
"surname" : "Pil"
}
Person{id=1909, father=Father{name='Wit', surname='Pil'}}
自2.6.7
以来,我已经对其进行了许多版本的测试,并且效果很好.
I've tested it for many version since 2.6.7
and it works fine.
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