Jackson Json 反序列化：无法识别的字段“...”，未标记为可忽略

Question

I'm getting the following error and no resolution i found did the trick for me:

Unrecognized field "GaugeDeviceId" (Class GaugeDevice), not marked as ignorable

The problem seems, that the service returns the property names with a leading upper letter, while the class properties begin with a lower letter.

I tried:

3. changing the propertyNames to first upper letter - same error
4. adding @JsonProperty("SerialNo") to the property instantiation - same error
5. adding @JsonProperty("SerialNo") to the corresponding getters - same error
6. adding @JsonProperty("SerialNo") to the corresponding setters - same error
7. adding @JsonProperty("SerialNo") to all of them (just for fun) - same error

(note: @JsonProperty("SerialNo") is just an example)

The strange thing is, that annotation: @JsonIgnoreProperties(ignoreUnknown = true) should suppress exactly that error, but it is still triggering...

here the Class: (note: not complete)

@JsonIgnoreProperties(ignoreUnknown = true)
public class GaugeDevice 
{
    private int gaugeDeviceId;
    private Date utcInstallation;
    private String manufacturer;
    private float valueOffset;
    private String serialNo;
    private String comment;
    private int digitCount;
    private int decimalPlaces;

    @JsonProperty("SerialNo")
    public String getSerialNo() {
        return serialNo;
    }

    public void setSerialNo(String serialNo) {
        this.serialNo = serialNo;
    }

    @JsonProperty("Comment")
    public String getComment() {
        return comment;
    }

    public void setComment(String comment) {
        this.comment = comment;
    }

Where is the way out here? Please help.

edit:

Here is the Client Class: (just a simple test client)

import ccc.android.meterdata.*;

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Invocation;
import org.glassfish.jersey.jackson.JacksonFeature;

public class RestClient
{
    private String connectionUrl;
    private javax.ws.rs.client.Client client;

    public RestClient(String baseUrl) {
         client = ClientBuilder.newClient();;
         connectionUrl = baseUrl;
         client.register(JacksonFeature.class); 
    }

    public GaugeDevice GetGaugeDevice(int id){

        String uri = connectionUrl + "/GetGaugeDevice/" + id;
        Invocation.Builder bldr = client.target(uri).request("application/json");
        return bldr.get(GaugeDevice.class);
    }
}

I hope the error has its root here?

Answer 1

I had the same issue and I resolved it by changing the annotation import from:

com.fasterxml.jackson.annotation.JsonIgnoreProperties

to

org.codehaus.jackson.annotate.JsonIgnoreProperties

Didn't have to define any NamingStrategy or ObjectMapper.

Answer 2

I had the same issue and solved it by changing the annotation import from

com.fasterxml.jackson.annotation.JsonProperty

to

org.codehaus.jackson.annotate.JsonProperty

Answer 3

Another thing to check out is PropertyNamingStrategy , which would allow Jackson to use "Pascal naming" and match JSON properties with POJO properties. See f.ex here: http://www.javacodegeeks.com/2013/04/how-to-use-propertynamingstrategy-in-jackson.html

Answer 4

Given the following is your error:

Unrecognized field "GaugeDeviceId" (Class GaugeDevice), not marked as ignorable

I'm pretty sure you need to do the same thing for the GaugeDeviceId property as you've done for the SerialNo property.

@JsonProperty("SerialNo")
public String getSerialNo() {
    return this.serialNo;
}

@JsonProperty("GaugeDeviceId")
public int getGaugeDeviceId() {
    return this.gaugeDeviceId;
}

Here I have a quick test class that is not throwing errors.

import org.codehaus.jackson.map.ObjectMapper;

public class JsonDeserialization {
    public static void main(final String[] args) {
        final String json = "{ \"SerialNo\":\"123\", \"GaugeDeviceId\":\"456\"}";

        final ObjectMapper mapper = new ObjectMapper();

        try {
            final GaugeDevice readValue = mapper.readValue(json, GaugeDevice.class);
            System.out.println(readValue.getSerialNo());
            System.out.println(readValue.getGaugeDeviceId());
        } catch (final Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

And it outputs:

123
456

EDIT: Version information

Not that it matters, as I believe the above is all using some pretty standard stuff from jackson, I'm using version 1.9.13 of the core-asl and the mapper-asl libraries

---

EDIT: Client Provided

I wonder if this is related to this issue ? I believe the resolution is the configuration of dependencies that you're using.

I'm not sure, but I feel like I'm close with the following dependency setup (note I'm using maven)

    <dependency>
        <groupId>javax.ws.rs</groupId>
        <artifactId>javax.ws.rs-api</artifactId>
        <version>2.0</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.media</groupId>
        <artifactId>jersey-media-json-jackson</artifactId>
        <version>2.0</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.core</groupId>
        <artifactId>jersey-client</artifactId>
        <version>2.0</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.media</groupId>
        <artifactId>jersey-media-json-processing</artifactId>
        <version>2.0</version>
    </dependency>

These links have provided the configuration information: Link 1 , Link 2

Answer 5

You can ignore the unknown properties while deserializing by using an annotation at class level.

For example :

@JsonIgnoreProperties(ignoreUnknown=true)
class Foo{
 ...
}

The above snippet will ignore any unknown properties. ( Annotation import : org.codehaus.jackson.annotate.JsonIgnoreProperties )

Answer 6

The solution that worked for me is the following

1. Add the import

   import org.codehaus.jackson.map.DeserializationConfig;

2. Configure the ObjectMapper

   objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES,false);

3. The complete solution

   ObjectMapper objectMapper = new ObjectMapper(); objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false); String jsonInString = objectMapper.writeValueAsString(eje); Eje newElement = objectMapper.readValue(jsonInString, Eje.class); this.eje = newElement;

Answer 7

Make all your private variables and members to public . Jackson works on public members variables.

public int gaugeDeviceId;
public Date utcInstallation; 
....

or add public Getters to private fields.