Estoy intentando deserialise por debajo JSON
de carga útil con Jackson
:
{"code":null,"reason":"subscription yet available","message":"{ Message:\"subscription yet available\", SubscriptionUID:\"46b62920-c519-4555-8973-3b28a7a29463\" }"}
pero yo estoy haciendo esto JsonMappingException
:
Cannot construct instance of `com.ids.utilities.DeserializeSubscription` (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)
at [Source: (String)"{"code":null,"reason":"subscription yet available","message":"{ Message:\"subscription yet available\", SubscriptionUID:\"46b62920-c519-4555-8973-3b28a7a29463\" }"}"; line: 1, column: 2]
He creado dos clases. La primera clase:
import lombok.Data;
@Data
public class DeserializeSubscription {
private String code;
private String reason;
private MessageSubscription message;
public DeserializeSubscription(String code, String reason, MessageSubscription message) {
super();
this.code = code;
this.reason = reason;
this.message = message;
}
y la segunda clase
import lombok.Data;
@Data
public class MessageSubscription {
private String message;
private String subscriptionUID;
public MessageSubscription(String message, String subscriptionUID) {
super();
this.message = message;
this.subscriptionUID = subscriptionUID;
}
En la clase principal:
try
{
ObjectMapper mapper = new ObjectMapper();
mapper.enable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT);
DeserializeSubscription desSub=null;
desSub=mapper.readValue(e.getResponseBody(), DeserializeSubscription.class);
System.out.println(desSub.getMessage().getSubscriptionUID());
}
catch (JsonParseException e1) {
// TODO Auto-generated catch block
e.printStackTrace();
}
catch (JsonMappingException e1) {
System.out.println(e1.getMessage());
e.printStackTrace();
}
catch (IOException e1) {
// TODO Auto-generated catch block
e.printStackTrace();
}
He encontrado esta solución pero que no funcionó https://facingissuesonit.com/2019/07/17/com-fasterxml-jackson-databind-exc-invaliddefinitionexception-cannot-construct-instance-of-xyz-no -creators-like-default-constructo-existir-no puede-deserializar-de-objeto de valor-no-delega /
The Jackson Maven que estoy usando en mi solicitud
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.10.2</version>
</dependency>
Usted tiene que considerar algunos casos:
message
en el campoJSON
es primitivoString
. EnPOJO
el nivel se trata de unMessageSubscription
objeto.message
valor enJSON
contiene los nombres de propiedades no cotizados, que es ilegal, peroJackson
los mangos ellos también.- Si el constructor no se ajusta a
JSON
lo que necesitamos configurarlo usando anotaciones.
Para manejar nombres no cotizados que necesitamos para permitir ALLOW_UNQUOTED_FIELD_NAMES función. Para hacer frente a falta de correspondencia entre JSON
la carga útil y POJO
tenemos que aplicar deserialiser personalizado para MessageSubscription
la clase.
deserialiser personalizada podría tener este aspecto:
class MessageSubscriptionJsonDeserializer extends JsonDeserializer<MessageSubscription> {
@Override
public MessageSubscription deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
final String value = p.getValueAsString();
final Map<String, String> map = deserializeAsMap(value, (ObjectMapper) p.getCodec(), ctxt);
return new MessageSubscription(map.get("Message"), map.get("SubscriptionUID"));
}
private Map<String, String> deserializeAsMap(String value, ObjectMapper mapper, DeserializationContext ctxt) throws IOException {
final MapType mapType = ctxt.getTypeFactory().constructMapType(Map.class, String.class, String.class);
return mapper.readValue(value, mapType);
}
}
Ahora, tenemos que personalizar DeserializeSubscription
's constructor:
@Data
class DeserializeSubscription {
private String code;
private String reason;
private MessageSubscription message;
@JsonCreator
public DeserializeSubscription(
@JsonProperty("code") String code,
@JsonProperty("reason") String reason,
@JsonProperty("message") @JsonDeserialize(using = MessageSubscriptionJsonDeserializer.class) MessageSubscription message) {
super();
this.code = code;
this.reason = reason;
this.message = message;
}
}
Ejemplo cómo usarlo:
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.type.MapType;
import lombok.Data;
import java.io.File;
import java.io.IOException;
import java.util.Map;
public class JsonPathApp {
public static void main(String[] args) throws Exception {
File jsonFile = new File("./resource/test.json").getAbsoluteFile();
ObjectMapper mapper = new ObjectMapper();
mapper.enable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT);
mapper.enable(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES);
DeserializeSubscription value = mapper.readValue(jsonFile, DeserializeSubscription.class);
System.out.println(value);
}
}
Para proporcionado JSON
carga útil por encima de ejemplo imprime:
DeserializeSubscription(code=null, reason=subscription yet available, message=MessageSubscription(message=subscription yet available, subscriptionUID=46b62920-c519-4555-8973-3b28a7a29463))