[英]How to skip wrapper object in jackson json deserialization
我正在尝试使用 jackson 反序列化以下字符串。
{
"roomName": "u8ec29p0j7q2m9f",
"broadcastPresenceRoles": {
"broadcastPresenceRole": [
"moderator",
"participant",
"visitor"
]
},
"owners": {
"owner": "anewuser@shahanshah"
},
"admins": {
"admin": "sanjeet@shahanshah"
},
"members": null,
"outcasts": {
"outcast": [
"sawan@shahanshah",
"sus@shahanshah"
]
},
"ownerGroups": {
"ownerGroup": "Friends"
}
}
这是来自 openfire rest apis 的响应。 我在包装数组的包装器对象上遇到问题。 这里
"broadcastPresenceRoles": {
"broadcastPresenceRole": [
"moderator",
"participant",
"visitor"
]
},
我试图用这个来打开容器,但没有成功。 我不认为编写包装类是个好主意(因为我将不得不编写几个包装类)。此外,我需要通用解决方案,以便我可以将它与其他响应一起使用,因为 apis 具有类似包装对象格式的其他响应. 提前致谢。
您可以在内部使用@JsonDeserialize
创建自定义注释,并创建一个实现ContextualDeserializer
的自定义JsonDeserializer
。 这个想法的灵感来自您提到的解决方案,但在 json 对象中解包任何一个属性更为通用。
以下是使用@JacksonAnnotationsInside
作为注释容器包含@JsonDeserialize
的自定义注释:
@Retention(RetentionPolicy.RUNTIME)
@JacksonAnnotationsInside
@JsonDeserialize(using = JsonUnwrapPropertyDeserializer.class)
public @interface JsonUnwrapProperty {
}
以及实现ContextualDeserializer
的自定义JsonDeserializer
:
public class JsonUnwrapPropertyDeserializer extends JsonDeserializer<Object> implements ContextualDeserializer {
private JavaType unwrappedJavaType;
private String unwrappedProperty;
@Override
public JsonDeserializer<?> createContextual(final DeserializationContext deserializationContext, final BeanProperty beanProperty) throws JsonMappingException {
unwrappedProperty = beanProperty.getMember().getName();
unwrappedJavaType = beanProperty.getType();
return this;
}
@Override
public Object deserialize(final JsonParser jsonParser, final DeserializationContext deserializationContext) throws IOException {
final TreeNode targetObjectNode = jsonParser.readValueAsTree().get(unwrappedProperty);
return jsonParser.getCodec().readValue(targetObjectNode.traverse(), unwrappedJavaType);
}
}
和使用示例:
public class MyBean {
@JsonProperty("broadcastPresenceRoles")
@JsonUnwrapProperty
private List<String> broadcastPresenceRole;
@JsonProperty("admins")
@JsonUnwrapProperty
private String admin;
// constructor, getter and setter
}
@JsonProperty
是定位包装器对象, @JsonUnwrappProperty
是反序列化json 对象并将属性提取到注释字段中。
编辑:
以下是ObjectMapper
的示例:
String json = "{\n" +
" \"broadcastPresenceRoles\": {\n" +
" \"broadcastPresenceRole\": [\n" +
" \"moderator\",\n" +
" \"participant\",\n" +
" \"visitor\"\n" +
" ]\n" +
" },\n" +
" \"admins\": {\n" +
" \"admin\": \"sanjeet@shahanshah\"\n" +
" }\n" +
"}";
final ObjectMapper mapper = new ObjectMapper();
final MyBean myBean = mapper.readValue(json, MyBean.class);
System.out.println(myBean.getBroadcastPresenceRole());
System.out.println(myBean.getAdmin());
输出:
[主持人、参与者、访客]
sanjeet@shahanshah
我创建了一个基于@wilson 响应解决 NPE 的变体
import java.io.IOException;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import com.fasterxml.jackson.annotation.JacksonAnnotationsInside;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.BeanProperty;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.deser.ContextualDeserializer;
@Retention(RetentionPolicy.RUNTIME)
@JacksonAnnotationsInside
@JsonDeserialize(using = JsonUnwrapProperty.JsonUnwrapPropertyDeserializer.class)
public @interface JsonUnwrapProperty {
public static class JsonUnwrapPropertyDeserializer extends JsonDeserializer<Object>
implements ContextualDeserializer {
private JavaType unwrappedJavaType;
private String unwrappedProperty;
@Override
public JsonDeserializer<?> createContextual(final DeserializationContext deserializationContext,
final BeanProperty beanProperty) throws JsonMappingException {
unwrappedProperty = beanProperty.getMember().getName();
unwrappedJavaType = beanProperty.getType();
return this;
}
@Override
public Object deserialize(final JsonParser jsonParser, final DeserializationContext deserializationContext)
throws IOException {
System.out.println(String.format("Ignoring %s in %s/%s", unwrappedProperty,
jsonParser.currentName(), jsonParser.nextFieldName()));
JsonToken token = jsonParser.nextValue();
return jsonParser.getCodec().readValue(jsonParser, unwrappedJavaType);
}
}
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.