Java 子类的Jackson序列化
在下面的示例中,我有一个主类-a和它的子类-B。它们都可以用作一般类X中的属性Java 子类的Jackson序列化,java,json,jackson,Java,Json,Jackson,在下面的示例中,我有一个主类-a和它的子类-B。它们都可以用作一般类X中的属性 public class A { @JsonProperty("primary_key") public final String primaryKey; @JsonCreator A(@JsonProperty("primary_key") String primaryKey) { this.primaryKey = primaryKey; } } public
public class A
{
@JsonProperty("primary_key")
public final String primaryKey;
@JsonCreator
A(@JsonProperty("primary_key") String primaryKey)
{
this.primaryKey = primaryKey;
}
}
public class B extends A
{
@JsonProperty("secondary_key")
public final String secondaryKey;
@JsonCreator
B(@JsonProperty("primary_key") String primaryKey, @JsonProperty("secondary_key") String secondaryKey)
{
super(primaryKey);
this.secondaryKey = secondaryKey;
}
}
public class X
{
@JsonProperty("keys")
public final A keys;
@JsonCreator
X(@JsonProperty("keys") A keys)
{
this.keys = keys;
}
}
如何使用Jackson多态特性将以下给定的json正确反序列化为各自的类:
JSON A:
{ "keys" :{
"primary_key" : "abc"
}
}
JSON B:
{ "keys" : {
"primary_key" : "abc",
"secondary_key" : "xyz"
}
}
预期结果:将keys对象映射到JSON A的类A和JSON B的类B
也请提供其他建议。如果我正确理解,只需传递值即可,无需任何配置。我相信这就是你想要的:
public class Test {
private static final String JSON = "{\"keys\":{\"primary_key\":\"abc\",\"secondary_key\":\"xyz\"}}";
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
X x = mapper.readValue(JSON, X.class);
System.out.println(mapper.writeValueAsString(x));
}
}
class A {
private String primary_key;
public String getPrimary_key() {
return primary_key;
}
public void setPrimary_key(String primary_key) {
this.primary_key = primary_key;
}
}
class B extends A {
private String secondary_key;
public String getSecondary_key() {
return secondary_key;
}
public void setSecondary_key(String secondary_key) {
this.secondary_key = secondary_key;
}
}
class X {
private B keys;
public B getKeys() {
return keys;
}
public void setKeys(B keys) {
this.keys = keys;
}
}
输出将是:
{"keys":{"primary_key":"abc","secondary_key":"xyz"}}
如果这不是您所期望的,请提供另一个解释,我将根据需要编辑答案。这感觉像是一个非常常见的问题,没有简单的方法来解决它(或者我只是找不到): 您可以做的一件事是将自定义反序列化器添加到对象映射器中。下面是这种方法的一个很好的演示: 下面是与您的示例相关的演示:
import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.ObjectCodec;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.module.SimpleModule;
import java.io.IOException;
public class Main4 {
private static final String jsonA = "{ \"keys\" : { \"primary_key\" : \"abc\" } }";
private static final String jsonB =
"{ \"keys\" : { \"primary_key\" : \"abc\", \"secondary_key\" : \"xyz\" } }";
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
SimpleModule idAsRefModule = new SimpleModule("ID-to-ref");
idAsRefModule.addDeserializer(A.class, new AJsonDeserializer());
mapper.registerModule(idAsRefModule);
X tl = mapper.readValue(jsonA, X.class);
System.out.println(tl);
X t2 = mapper.readValue(jsonB, X.class);
System.out.println(t2);
}
public static class AJsonDeserializer extends JsonDeserializer<A>{
@Override
public A deserialize(JsonParser jp, DeserializationContext dc)
throws IOException {
ObjectCodec codec = jp.getCodec();
JsonNode node = codec.readTree(jp);
if (node.has("secondary_key")) {
return codec.treeToValue(node, B.class);
}
return new A(node.findValue("primary_key").asText());
}
}
public static class A
{
@JsonProperty("primary_key")
public final String primaryKey;
@JsonCreator
A(@JsonProperty("primary_key") String primaryKey)
{
this.primaryKey = primaryKey;
}
@Override
public String toString() {
return "A{" +
"primaryKey='" + primaryKey + '\'' +
'}';
}
}
public static class B extends A
{
@JsonProperty("secondary_key")
public final String secondaryKey;
@JsonCreator
B(@JsonProperty("primary_key") String primaryKey,
@JsonProperty("secondary_key") String secondaryKey)
{
super(primaryKey);
this.secondaryKey = secondaryKey;
}
@Override
public String toString() {
return "B{" +
"primaryKey='" + primaryKey + '\'' +
"secondaryKey='" + secondaryKey + '\'' +
'}';
}
}
public static class X
{
@JsonProperty("keys")
public final A keys;
@JsonCreator
X(@JsonProperty("keys") A keys)
{
this.keys = keys;
}
@Override
public String toString() {
return "X{" +
"keys=" + keys +
'}';
}
}
}
import com.fasterxml.jackson.annotation.*;
导入com.fasterxml.jackson.core.JsonParser;
导入com.fasterxml.jackson.core.ObjectCodec;
导入com.fasterxml.jackson.databind.*;
导入com.fasterxml.jackson.databind.module.SimpleModule;
导入java.io.IOException;
公共类main 4{
私有静态最终字符串jsonA=“{\'keys\”:{\'primary\u key\”:\'abc\'}”;
私有静态最终字符串jsonB=
“{\'keys\':{\'primary\'u key\':\'abc\',\'secondary\'u key\':\'xyz\'}”;
公共静态void main(字符串[]args)引发IOException{
ObjectMapper mapper=新的ObjectMapper();
SimpleModule idAsRefModule=新的SimpleModule(“ID到ref”);
addDeserializer(A.class,新的AJsonDeserializer());
mapper.registerModule(idAsRefModule);
X tl=mapper.readValue(jsonA,X.class);
系统输出打印项次(tl);
x2=mapper.readValue(jsonB,X.class);
系统输出打印项次(t2);
}
公共静态类AJsonDeserializer extends JsonDeserializerİt不清楚您的实际结果和预期结果是什么?@YusufK。我想将第一个json映射到类A,第二个json映射到类B。我想您想从每个给定的json创建对象吗?是@YusufK。我想从给定的json创建对象。如果(给定json包含“secondary_key”),那么X中的keys对象应该属于B,否则X中的keys对象应该属于A