Java consume JSON list from Rest service GET

Question

The error I receive:

SEVERE: A message body reader for Java class java.util.List, 
and Java type java.util.List<com.testapp.Category>, 
and MIME media type text/html; charset=utf-8 was not found

Trying to consume a JSON response from a Rest service using the GET method with Jersey. The response from the server looks like this when I use curl:

[{"category":{"id":"4d9c5dfc8ddfd90828000002","description":"Cows"}},
{"category":{"id":"4d9c5dfc8ddfd90828000023","description":"Dogs"}},
...
{"category":{"id":"4d9c5dfc8ddfd90828000024","description":"Mules"}}]

Consuming the service with:

public List<Category> getAnimalCategories(Cookie cookie) {
    Client client = Client.create(new DefaultClientConfig());
    ClientResponse response = client
        .resource(Constants.BASE_URL)
        .path(Constants.CATEGORIES_ANIMALS)
        .accept(MediaType.APPLICATION_JSON)
        .type(MediaType.APPLICATION_JSON)
        .cookie(cookie)
        .get(ClientResponse.class);

    return response.getEntity(new GenericType<List<Category>>(){});
}

Where Category.java is:

public class Category {

public String id;
public String description;

public Category() {
}

public Category(String id, String description) {
    super();
    this.id = id;
    this.description = description;
}

The service uses cookie based authentication - that part works and I have other service calls working with the cookie.

possible duplicate of Cannot unmarshal a JSON array of objects using Jersey Client — bdoughan
– bdoughan, Commented Apr 2, 2012 at 20:38
Fixed by adding the Jackson 1.9.6 jar and adding to the ClientConfig: clientConfig.getClasses().add(JacksonJsonProvider.class); — Cobus Bernard
– Cobus Bernard, Commented Apr 2, 2012 at 21:34

Cobus Bernard · Accepted Answer · 2012-04-03 06:42:33Z

5

Used the Jackson 1.9.6 lib to resolve the issue - see the 2nd line below:

ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getClasses().add(JacksonJsonProvider.class);
Client client = Client.create(clientConfig);

return client
    .resource(Constants.BASE_URL)
    .path(Constants.CATEGORIES_ANIMALS)
    .type(MediaType.APPLICATION_JSON)
    .accept(MediaType.APPLICATION_JSON)
    .cookie(cookie)
    .get(new GenericType<List<AnimalCategoryResponse>>(){});

Also needed to use a new response class:

public class AnimalCategoryResponse {
    public Category[] category;
    public AnimalCategoryReponse() { }
}

answered Apr 3, 2012 at 6:42

Cobus Bernard

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1 Comment

Chris Hinshaw Over a year ago

Thanks I had this problem for quite a while, I saw somewhere in the jersey documenation that it would scan the classpath for providers and the JacksonProvider would be automatically discovered but this appears to be incorrect. After addin the JacksonJsonProvider it my code works.

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