为了确保在我的RESTful web服务中来回发送的数据不是多余的,每个嵌套对象都只有ID序列化(Message
的User
创建者只有userId
序列化,因为客户机和服务器都会知道用户的所有细节)。
序列化工作得很好,产生了以下结果:
{"messageCreatorUser":"60d01602-c04d-4a3f-bbf2-132eb0ebbfc6","messageBody":"Body", ...}
Problem:反序列化不会产生只具有ID的嵌套对象。结果反序列化的嵌套对象为null。
下面是前面提到的Message
和User
对象。在这里指定的第三个选项中使用了序列化“策略”:How to serialize only the ID of a child with Jackson。
Message.java
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "messageId")
public class Message implements Serializable {
// -- Hibernate definitions omitted --
private UUID messageId;
// -----------------------------------------------------------------
// Here is what makes the serializer print out the ID specified on the class definition
@JsonIdentityReference(alwaysAsId = true)
// Here is my attempt to get the User class back when I deserialize
@JsonDeserialize(as = User.class)
@JsonSerialize(as = User.class)
private User messageCreatorUser;
// ------------------------------------------------------------------
// -- more arbitrary properties --
public Message() {
}
public Message(UUID messageId) {
this.messageId = messageId;
}
public Message(String messageId) {
this.messageId = UUID.fromString(messageId);
}
// -- getters and setters --
User.java
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "userId")
@JsonInclude(JsonInclude.Include.NON_NULL)
public class User implements Serializable {
private UUID userId;
// -- other arbitrary properties --
public User() {
}
public User(UUID userId) {
this.userId = userId;
}
public User(String userId) {
this.userId = UUID.fromString(userId);
}
// -- getters and setters --
预期反序列化对象:
Message object =
String messageBody = "Body";
User messageCreatorUser =
UUID userId = 60d01602-c04d-4a3f-bbf2-132eb0ebbfc6;
实际反序列化对象:
Message object =
String messageBody = "Body";
User messageCreatorUser = null;
就像我说的,我希望创建一个嵌套的User
对象,只使用60d01602-c04d-4a3f-bbf2-132eb0ebbfc6
的ID。
使用:
为什么结果不同?
发布于 2016-07-18 20:37:03
正如这里的答案(Jackson deserialize JsonIdentityReference (alwaysAsId = true))所述,使用setter反序列化器工作得很好,不需要讨厌的自定义反序列化器:
Message.java
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "messageId")
public class Message implements Serializable {
private UUID messageId;
@JsonIdentityReference(alwaysAsId = true)
private User messageCreatorUser;
// -- other fields and such --
public User getMessageCreatorUser() {
return messageCreatorUser;
}
public void setMessageCreatorUser(User messageCreatorUser) {
this.messageCreatorUser = messageCreatorUser;
}
@JsonProperty("messageCreatorUser")
public void setMessageCreatorUser(String userId) {
this.messageCreatorUser = new User(userId);
}
User.java
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "userId")
public class User implements Serializable {
private UUID userId;
// -- other fields --
public User(String userId) {
this.userId = UUID.fromString(userId);
}
}
请注意,为了使用@JsonIdentityReference(alwaysAsId = true)
,您需要在某个地方拥有@JsonIdentityInfo(...)
。
https://stackoverflow.com/questions/38443016
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