杰克逊系列化问题

Question

我在序列化/反序列化下面的类时遇到一些问题。

我的Data类包含其他类的列表。

当我调用Data类中的序列化/反序列化方法时，我会得到以下错误：

Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.amazon.rancor.storage.types.ChildData: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?)

错误来自反序列化方法。但我也认为序列化工作不正常。这就是序列化的Data对象的样子：

{childData:[{zipCode:{present:true},countryCode:"US"}]

尽管我已经设置了objectMapper.registerModule(new Jdk8Module());字段，但可选字段没有正确序列化

---

我似乎不明白自己做错了什么。也许我需要更改ChildData和ChildDataV2类中的某些内容。但我不确定是什么。

任何建议都将不胜感激！

---

public class Data {
private List<ChildData> childData;
private List<ChildDataV2> childDataV2;
private static ObjectMapper objectMapper;
static {
objectMapper = new ObjectMapper();
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
objectMapper.registerModule(new Jdk8Module());
}
public Data() { }
@JsonCreator
public Data(@JsonProperty("childData") final List<ChildData> childData,
@JsonProperty("childDataV2") final List<ChildDataV2> childDataV2) {
this.childData = childData;
this.childDataV2 = childDataV2;
}
public List<ChildData> getChildData() {
return childData;
}

public void setChildData(final List<ChildData> childData) {
this.childData = childData;
}
public List<ChildDataV2> getChildDataV2() {
return childDataV2;
}
public void setChildDataV2(final List<ChildDataV2> childDataV2) {
this.childDataV2 = childDataV2;
}
public String serialize() {
try {
return objectMapper.writeValueAsString(this);
} catch (JsonProcessingException e) {
throw new RuntimeException("Failed to serialize. Data: " + this, e);
}
}
public Data deSerialize(final String data) {
try {
return objectMapper.readValue(data, Data.class);
} catch (IOException e) {
throw new RuntimeException("Failed to deserialize. Data" + data, e);
}
}
}

public class ChildData {
private final String countryCode;
private final Optional<String> zipCode;
public ChildData(final String countryCode, final Optional<String> zipCode) {
this.countryCode = countryCode;
this.zipCode = zipCode;
}
public Optional<String> getZipCode() {
return zipCode;
}
public String getCountryCode() {
return countryCode;
}
}

public class ChildDataV2 extends ChildData {
private final Object struct;
public ChildDataV2(final String cc, final Optional<String> postalCode,
final Object struct) {
super(cc, postalcode);
this.struct = struct;
}
}

Answer 1

异常非常清楚，对吗？您需要为ChildData添加一个默认构造函数，或者像这样注释现有构造函数：

@JsonCreator
public ChildData(@JsonProperty("countryCode") String countryCode, @JsonProperty("zipCode") Optional<String> zipCode) {
this.countryCode = countryCode;
this.zipCode = zipCode;
}