cloud endpoint not respecting Jackson annotations

问题:

I have a class Organization with few date fields as follows.

public class Organization {

    private String _id;

    private String name;

    @JsonDeserialize(using=JsonDateDeserializer.class)
    @JsonSerialize(using=JsonDateSerializer.class)
    private Date createdTime;

// getters and setters

}

To handle the date in simple way on client side I convert date to long and send it to client using these JsonSerializer as follows

public class JsonDateSerializer extends JsonSerializer<Date>{

    @Override
    public void serialize(Date date, JsonGenerator gen, SerializerProvider provider) throws IOException, JsonProcessingException {
        gen.writeNumber(date.getTime());
    }

}

I have a endpoint which will execute get organization and insert the results in response map like this.

@ApiMethod(name="organization.get", path="organizations/{organizationId}", httpMethod=HttpMethod.GET)
public Map<String, Object> organizationDetails(@Named("organizationId") String organizationId){
    Organization org = DB.getOrganization("123");
    Map<String, Object> response = new HashMap<String, Object>();
    response.put("status", HttpServletResponse.SC_OK);
    response.put("success", true);
    response.put("entity", org);
    return response;
} 

But the end resultant JSON I see on client side is

{
  "status" : 200,
  "entity" : [ {
    "_id" : "966a03b3-8e46-41ee-b330-6533409b2b4a",
    "name" : "POKURI",    
    "createdTime" : "2015-05-16T15:02:31.499+05:30"
  } ],
  "success" : true
}

Here the date coming in some format instead of long. If I convert the same using Jackson ObjectMapper without using cloud endpoints I am getting response in expected way. Why cloud endpoints not respecting Jackson annotations? Is there a way to configure that?

Note: Even I observed that long is coming as string on client side if you use cloud endpoints. I am using appengine SDK 1.9.19

回答1:

You aren't supposed to use Jackson annotations with Endpoints (and if you do, you have to use the repackaged version, not your own). You can do what you want with @ApiResourceProperty or @ApiTransformer, depending on how you want to do it. See the annotation documentation here.

Regarding long, it is serialized as a string due to floating point imprecision--it's not possible to represent all values of a long accurately using a double, which is what JavaScript and JSON.parse will store a numeric in, so it is always transmitted as a string. Any of our client libraries for Endpoints automatically convert them to the correct data type.