Jackson，序列化引用的一个属性

当序列化具有其他对象引用的Java对象时，我只需要序列化嵌套对象的一个​​属性（通常是外键，因此序列化对象引用的“id”属性）。英戈尔其他一切。

例如，我有两个类需要序列化为 JSON 和 XML（为了清楚起见，删除了 JPA 注释）：

关系：用户->（一对多）地址信息； 另外：地址信息 ->（一对一）用户

@XmlRootElement
public class User {
    private String id;
    private String firstName;
    private String lastName;
    private String email;
    private AddressInformation defaultAddress;
    private Set<AddressInformation> addressInformation;

    public User() {
    }

    @JsonProperty(value = "id")
    @XmlAttribute(name = "id")
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    @JsonProperty(value = "firstname")
    @XmlAttribute(name = "firstname")
    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    @JsonProperty(value = "lastname")
    @XmlAttribute(name = "lastname")
    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    @JsonProperty(value = "email")
    @XmlAttribute(name = "email")
    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @JsonIgnore
    public Set<AddressInformation> getAddressInformation() {
        return addressInformation;
    }

    public void setAddressInformation(Set<AddressInformation> addressInformation) {
        this.addressInformation = addressInformation;
    }

    @JsonProperty(value = "defaultaddress")
    @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
    public AddressInformation getDefaultAddress() {
        return defaultAddress;
    }

    public void setDefaultAddress(AddressInformation defaultAddress) {
        this.defaultAddress = defaultAddress;
    }
}

地址信息：

@XmlRootElement
public class AddressInformation  {
    private String id;
    private String address;
    private String details;
    private User user;

    @JsonProperty(value = "id")
    @XmlAttribute(name = "id")
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    @JsonProperty(value = "details")
    @XmlAttribute(name = "details")
    public String getDetails() {
        return details;
    }

    public void setDetails(String details) {
        this.details = details;
    }

    @JsonProperty(value = "address")
    @XmlAttribute(name = "address")
    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public AddressInformation() {
        super();
    }
}
enter code here

例如，当序列化 User 时，我需要：

{
  "id" : "idofuser01",
  "email" : "[email protected]",
  "status" : "OK",
  "firstname" : "Filan",
  "lastname" : "Ovni",
  "defaultaddressid" : "idofaddress01",
}
enter code here

序列化AddressInformation时：

{
  "id" : "idofaddress01",
  "address" : "R.8. adn",
  "details" : "blah blah",
  "userid" : "idofuser01",
}

我努力了@JsonManageReference & @JsonBackReference没有成功。正如你所看到的，我也尝试过@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")

刚刚找到了一种使用 Jackson 2.1+ 的方法。

用（这将仅选择id的属性AddressInformation):

@JsonProperty(value = "defaultaddressid")
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
@JsonIdentityReference(alwaysAsId = true) 
public AddressInformation getDefaultAddress() {
    return defaultAddress;
}

序列化效果非常好。