Jersey ClientResponse.getEntity of generic type

Question

I got a problem to deserialize using jeresy ClientRespone.getEntity

I've tried to follow some tutorials and questions, include this: http://jersey.576304.n2.nabble.com/How-can-I-parse-a-java-util-List-lt-gt-Is-it-supported-by-the-Jersey-client-td2300852.html https://jersey.java.net/nonav/documentation/1.5/json.html http://www.programcreek.com/java-api-examples/index.php?api=com.sun.jersey.api.client.GenericType

and i still got the same exception over and over again..

My goal is: instead of:

response.getEntity(String.class); --> {"name":"Ben","type":"The man","id":0}

and then parse it (using Jackson for example), I want to get the entity into my POJO object.

this is my tryings so far:

ServerSide:

@POST
@Path("/account") // route to a specific method.re
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response saveDataIntoHash(Account account) {
    Account createdAccount = new Account(account.getName(), account.getType());
    accountHash.put(createdAccount.getID(), createdAccount);
    return Response.status(201).entity(new AccountResponse(createdAccount.getID())).build();
}

Server side Account Class:

private String name;
private String type;
private int ID;

private static int classID = 0;

public Account(String name, String type) {
    this.name = name;
    this.type = type;
    this.ID = classID++;
}

public Account() {
}

public void setName(String name) { this.name = name; }

public String getName() { return name; }

public void setType(String type) { this.type = type; }

public String getType() { return type; }

public int getID() {
    return ID;
}

public void setID(int ID) {
    this.ID = ID;
}

public static int getClassID() {
    return classID;
}

public static void setClassID(int classID) {
    Account.classID = classID;
}

ClientSide

private static void getToRestPartner(Client client) {
    WebResource webResource = client.resource("http://localhost:8080/RESTfulExample/rest/account/0");
    ClientResponse response = webResource.type("application/json").get(ClientResponse.class);

    if (!(response.getStatus() == 201 || response.getStatus() == 200)) {
        throw new RuntimeException("Failed : HTTP error code : " + response.getStatus());
    }

    System.out.println("Output from Server .... \n");

    List<Account> accountList =  response.getEntity(new GenericType<List<Account>>() {
    });

    System.out.println(accountList.size());
}

Client Account class:

@XmlRootElement
public class Account {
@XmlElement
private String name;
@XmlElement
private String type;
@XmlElement
private int id;

public Account(String name, String type, Integer id) {
    this.name = name;
    this.type = type;
    this.id = id;
}

public Account() {
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getType() {
    return type;
}

public void setType(String type) {
    this.type = type;
}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

It throws this exception:

Dec 7, 2014 12:15:58 PM com.sun.jersey.api.client.ClientResponse getEntity
SEVERE: A message body reader for Java class java.util.List, and Java type java.util.List<Account>, and MIME media type application/json was not found
Dec 7, 2014 12:15:58 PM com.sun.jersey.api.client.ClientResponse getEntity
SEVERE: The registered message body readers compatible with the MIME media type are:
*/* ->
  com.sun.jersey.core.impl.provider.entity.FormProvider
  com.sun.jersey.core.impl.provider.entity.StringProvider
  com.sun.jersey.core.impl.provider.entity.ByteArrayProvider
  com.sun.jersey.core.impl.provider.entity.FileProvider
  com.sun.jersey.core.impl.provider.entity.InputStreamProvider
  com.sun.jersey.core.impl.provider.entity.DataSourceProvider
  com.sun.jersey.core.impl.provider.entity.XMLJAXBElementProvider$General
  com.sun.jersey.core.impl.provider.entity.ReaderProvider
  com.sun.jersey.core.impl.provider.entity.DocumentProvider
  com.sun.jersey.core.impl.provider.entity.SourceProvider$StreamSourceReader
  com.sun.jersey.core.impl.provider.entity.SourceProvider$SAXSourceReader
  com.sun.jersey.core.impl.provider.entity.SourceProvider$DOMSourceReader
  com.sun.jersey.core.impl.provider.entity.XMLRootElementProvider$General
  com.sun.jersey.core.impl.provider.entity.XMLListElementProvider$General
  com.sun.jersey.core.impl.provider.entity.XMLRootObjectProvider$General
  com.sun.jersey.core.impl.provider.entity.EntityHolderReader

Exception in thread "main" com.sun.jersey.api.client.ClientHandlerException: A message body reader for Java class java.util.List, and Java type java.util.List<Account>, and MIME media type application/json was not found
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:549)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:523)
    at com.sample.Sample.getToRestPartner(Sample.java:59)
    at com.sample.Sample.main(Sample.java:22)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)

Your help will be appreciated !!

Answer 1

Few things either need to be fixed or added (not sure in your case as some parts are missing)

Resource: Made my own to test, as yours was missing a few items

@Path("/")
public class AccountResource {
    @GET
    @Path("/account") // route to a specific method.re
    @Produces(MediaType.APPLICATION_JSON)
    public Response saveDataIntoHash() {
        List<Account> accounts = new ArrayList<Account>();
        accounts.add(new Account("Stack", "Savings"));
        accounts.add(new Account("Overflow", "Checkings"));
        GenericEntity generic = new GenericEntity<List<Account>>(accounts){};
        return Response.status(201).entity(generic).build();
    }
}

Assumed you have this dependency:

<dependency>
    <groupId>com.sun.jersey</groupId>
    <artifactId>jersey-json</artifactId>
    <version>${jersey-version}</version>
</dependency>

Test case: Notice the client configuration. This is needed.

public void testMyResource() {
    ClientConfig config = new DefaultClientConfig();
    config.getClasses().add(JacksonJaxbJsonProvider.class);
    config.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);

    Client c = Client.create(config);

    WebResource resource = c.resource(Main.BASE_URI);
    ClientResponse response = resource.path("account")
            .accept("application/json").get(ClientResponse.class);

    List<Account> accounts
                = response.getEntity(new GenericType<List<Account>>(){});

    StringBuilder builder = new StringBuilder("=== Accounts ===\n");
    for (Account account: accounts) {
        builder.append("Name: ").append(account.getName()).append(", ")
                .append("Type: ").append(account.getType()).append("\n");          
    }
    builder.append("==================");
    System.out.println(builder.toString());    
}

Account (client) class is missing one annotation. It is required as you are using field annotations. Another option is to add a getter and setter for the id

@XmlRootElement  
@XmlAccessorType(XmlAccessType.FIELD)  // <======= This Here
public class Account {
    // added toString for testing
    @Override
    public String toString() {
        return "Account{" + "name=" + name 
                          + ", type=" + type 
                          + ", id=" + id + '}';
    }
}

Result from test:

=== Accounts ===
Name: Stack, Type: Savings
Name: Overflow, Type: Checkings
==================

Note: this test is based on the assumption that nothing is wrong on your server side.