Getting JSON out put from restful java client

Question

I'm developing a web service using REST (Jersey 1.8). Currently I'm using XML to communicate between the Java client and the server.

I need to change it to JSON: how can I do that? I have bunch of auto generated code from NetBeans, and have no idea what to do and how. When the testing the service it shows the JSON data. What I'm unable to do is deal with it within my main method.

these are the tutorial I followed

• http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/RESTfulWebServices/RESTfulWebservices.htm
• http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/RESTfulWebServices_Part2/RESTfulWebservicesPart2.htm
• http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/RESTfulWebServices_Part3/RESTfulWebservicesPart3.htm

My Java client main method:

public class SOATestClient {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        PersonJerseyClient client = new PersonJerseyClient();
        ClientResponse response = client.findAll_XML(ClientResponse.class);


        GenericType<List<Person>> genericType = new GenericType<List<Person>>() {
        };
// Returns an ArrayList of Players from the web service
        List<Person> data = new ArrayList<Person>();
        data = (response.getEntity(genericType));
        System.out.println("Retreiving and Displaying Players Details");
        for (Person person : data) {
            System.out.println("FirstName: " + person.getName());
            System.out.println("ID : " + person.getId());
            System.out.println(" Age : " + person.getAge());
        }
        client.close();
    }
}

personjerseycilent

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package jerseyclients;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.UniformInterfaceException;
import com.sun.jersey.api.client.WebResource;

/**
 * Jersey REST client generated for REST resource:PersonFacadeREST
 * [entity.person]<br>
 *  USAGE:
 * <pre>
 *        PersonJerseyClient client = new PersonJerseyClient();
 *        Object response = client.XXX(...);
 *        // do whatever with response
 *        client.close();
 * </pre>
 *
 * @author rj45
 */
public class PersonJerseyClient {
    private WebResource webResource;
    private Client client;
    private static final String BASE_URI = "http://localhost:8080/SOATestService/resources";

    public PersonJerseyClient() {
        com.sun.jersey.api.client.config.ClientConfig config = new com.sun.jersey.api.client.config.DefaultClientConfig();
        client = Client.create(config);
        webResource = client.resource(BASE_URI).path("entity.person");
    }

    public void remove(String id) throws UniformInterfaceException {
        webResource.path(java.text.MessageFormat.format("{0}", new Object[]{id})).delete();
    }

    public String countREST() throws UniformInterfaceException {
        WebResource resource = webResource;
        resource = resource.path("count");
        return resource.accept(javax.ws.rs.core.MediaType.TEXT_PLAIN).get(String.class);
    }

    public <T> T findAll_XML(Class<T> responseType) throws UniformInterfaceException {
        WebResource resource = webResource;
        return resource.accept(javax.ws.rs.core.MediaType.APPLICATION_XML).get(responseType);
    }

    public <T> T findAll_JSON(Class<T> responseType) throws UniformInterfaceException {
        WebResource resource = webResource;
        return resource.accept(javax.ws.rs.core.MediaType.APPLICATION_JSON).get(responseType);
    }

    public void edit_XML(Object requestEntity) throws UniformInterfaceException {
        webResource.type(javax.ws.rs.core.MediaType.APPLICATION_XML).put(requestEntity);
    }

    public void edit_JSON(Object requestEntity) throws UniformInterfaceException {
        webResource.type(javax.ws.rs.core.MediaType.APPLICATION_JSON).put(requestEntity);
    }

    public void create_XML(Object requestEntity) throws UniformInterfaceException {
        webResource.type(javax.ws.rs.core.MediaType.APPLICATION_XML).post(requestEntity);
    }

    public void create_JSON(Object requestEntity) throws UniformInterfaceException {
        webResource.type(javax.ws.rs.core.MediaType.APPLICATION_JSON).post(requestEntity);
    }

    public <T> T findRange_XML(Class<T> responseType, String from, String to) throws UniformInterfaceException {
        WebResource resource = webResource;
        resource = resource.path(java.text.MessageFormat.format("{0}/{1}", new Object[]{from, to}));
        return resource.accept(javax.ws.rs.core.MediaType.APPLICATION_XML).get(responseType);
    }

    public <T> T findRange_JSON(Class<T> responseType, String from, String to) throws UniformInterfaceException {
        WebResource resource = webResource;
        resource = resource.path(java.text.MessageFormat.format("{0}/{1}", new Object[]{from, to}));
        return resource.accept(javax.ws.rs.core.MediaType.APPLICATION_JSON).get(responseType);
    }

    public <T> T find_XML(Class<T> responseType, String id) throws UniformInterfaceException {
        WebResource resource = webResource;
        resource = resource.path(java.text.MessageFormat.format("{0}", new Object[]{id}));
        return resource.accept(javax.ws.rs.core.MediaType.APPLICATION_XML).get(responseType);
    }

    public <T> T find_JSON(Class<T> responseType, String id) throws UniformInterfaceException {
        WebResource resource = webResource;
        resource = resource.path(java.text.MessageFormat.format("{0}", new Object[]{id}));
        return resource.accept(javax.ws.rs.core.MediaType.APPLICATION_JSON).get(responseType);
    }

    public void close() {
        client.destroy();
    }

}

I try to access it with the following, and deal it with same way as XML,

ClientResponse response = client.findAll_JSON(ClientResponse.class);

but it gives me

Exception in thread "main" javax.ws.rs.WebApplicationException: javax.xml.bind.UnmarshalException
 - with linked exception:
[com.sun.istack.internal.SAXParseException2; lineNumber: 0; columnNumber: 0; unexpected element (uri:"", local:"id"). Expected elements are <{}person>]
    at com.sun.jersey.core.provider.jaxb.AbstractListElementProvider.readFrom(AbstractListElementProvider.java:251)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:553)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:523)
    at soatestclient.SOATestClient.main(SOATestClient.java:33)
Caused by: javax.xml.bind.UnmarshalException

I would be grateful to if you could help me on this matter. Thank you!

Answer 1

i resolved the same question. if your exception is : unexpected element (uri:"", local:"id").........

don't forget add follow code:

    DefaultClientConfig clientConfig = new DefaultClientConfig();
    clientConfig.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);
    Client client = Client.create(clientConfig);

then the code:

return resource.type(MediaType.APPLICATION_JSON_TYPE).get(new GenericType<List<MyClass>>(){});

will be ok.

Answer 2

1) Whoever is generating this error, is clearly expecting XML input. Not JSON. You need to change that ASAP:

 javax.ws.rs.WebApplicationException: javax.xml.bind.UnmarshalException
 com.sun.istack.internal.SAXParseException2;
 <= javax.xml.bind and SAXParse are both XML-only: JSON not invited

2) The stuff in your screen shot (presumably Jersey?) is definitely OK.

3) I haven't followed the whole tutorial, and you haven't given enough information to tell where you went astray.

SUGGESTION:

Just retrace your steps in the tutorial, and make sure you're selecting "JSON" ( not XML, and not SOAP) every step of the way.

=========== ADDENDUM ===========

OK - Thanx for the update. Here's where we're at:

1) This is the problem:

Exception in thread "main" javax.ws.rs.WebApplicationException: javax.xml.bind.UnmarshalException
 - with linked exception:
[com.sun.istack.internal.SAXParseException2; lineNumber: 0; columnNumber: 0; unexpected element (uri:"", local:"id"). Expected elements are <{}person>]
    at com.sun.jersey.core.provider.jaxb.AbstractListElementProvider.readFrom(AbstractListElementProvider.java:251)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:553)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:523)
    at soatestclient.SOATestClient.main(SOATestClient.java:33)
Caused by: javax.xml.bind.UnmarshalException

2) You said this stack traceback is coming from the client.

So your server is 100% OK - the ONLY thing you need to do is fix your client. Cool :)

3) The traceback shows the client is expecting XML ... but getting JSON instead.

So the ONLY thing you should need to fix is to tell your client "Hey: read JSON, not XML". Again - cool :)

4) How do you do that?

Well, for starters, you need to get rid of this line (if you haven't already):

// Bad, bad bad.  Don't do this!|
ClientResponse response = client.findAll_XML(ClientResponse.class);

5) You might want to change other parts of your client code - I don't know.

You might also want to change your client's configuration - I don't know that, either.

6) Suggestion: look at this other tutorial - it might point you in the right direction:

• http://www.vogella.com/articles/REST/article.html

NOTE:

WHATEVER you need to do - it should be REALLY simple! Please review the link, review your code and your test client configuration ... and post back what you find!

Thank you in advance...

Answer 3

http://smoothexample.com/webservices/apache_cxf_rest_web_services_client.html

The above example gives sample client application using apache cxf, here client can consume both xml and json by providing the "Accept" header.

Also a simple example for cxf rest web service is also available here, which even returns both xml and json based on the "Accept" header.