How to use Genson provider as default in Jersey client?

Question

I have simple client based on Jersey framework.
I want to use Genson as default JSON provider.
Firstly I created some class which implemented ContextResolver :

@Provider
public class GensonCustomResolver implements ContextResolver<Genson> {

    private final Genson genson = new Genson.Builder().setSkipNull(true).setDateFormat(new UtcDateFormat()).create();

    @Override
    public Genson getContext(Class<?> type) {
        return genson;
    }
}

And UtcDateFormat class:

public class UtcDateFormat extends DateFormat {
    @Override
    public StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition) {
        return new StringBuffer("" + date.getTime());
    }

    @Override
    public Date parse(String source, ParsePosition pos) {
        return new Date(Long.parseLong(source));
    }
}

Then I used this:

ClientConfig cfg = new DefaultClientConfig(GensonCustomResolver.class);
Client client = Client.create(cfg);

Integer meetingId = 1;

Meeting result = client.resource("http://mywebservise.com/").path("meeting")
.path(meetingId.toString()).get(ClientResponse.class).getEntity(Meeting.class);

But, it failed. Here are log:

javax.ws.rs.WebApplicationException: com.owlike.genson.TransformationException: Could not deserialize to property 'created' of class class com.mypack.model.Meeting
    at com.owlike.genson.ext.jaxrs.GensonJsonConverter.readFrom(GensonJsonConverter.java:127)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:565)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:517)
    at com.mypack.ws.MeetingsTest.getItem(MeetingsTest.java:159)
    at com.mypack.ws.MeetingsTest.getItem(MeetingsTest.java:68)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:85)
    at org.testng.internal.Invoker.invokeMethod(Invoker.java:659)
    at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:845)
    at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1153)
    at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
    at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:108)
    at org.testng.TestRunner.privateRun(TestRunner.java:771)
    at org.testng.TestRunner.run(TestRunner.java:621)
    at org.testng.SuiteRunner.runTest(SuiteRunner.java:357)
    at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:352)
    at org.testng.SuiteRunner.privateRun(SuiteRunner.java:310)
    at org.testng.SuiteRunner.run(SuiteRunner.java:259)
    at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
    at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
    at org.testng.TestNG.runSuitesSequentially(TestNG.java:1199)
    at org.testng.TestNG.runSuitesLocally(TestNG.java:1124)
    at org.testng.TestNG.run(TestNG.java:1032)
    at org.gradle.api.internal.tasks.testing.testng.TestNGTestClassProcessor.stop(TestNGTestClassProcessor.java:110)
    at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:58)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.gradle.messaging.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:35)
    at org.gradle.messaging.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
    at org.gradle.messaging.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:32)
    at org.gradle.messaging.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:93)
    at com.sun.proxy.$Proxy2.stop(Unknown Source)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker.stop(TestWorker.java:113)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.gradle.messaging.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:35)
    at org.gradle.messaging.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
    at org.gradle.messaging.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:355)
    at org.gradle.internal.concurrent.DefaultExecutorFactory$StoppableExecutorImpl$1.run(DefaultExecutorFactory.java:66)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)
Caused by: com.owlike.genson.TransformationException: Could not deserialize to property 'created' of class class com.mypack.model.Meeting
    at com.owlike.genson.reflect.PropertyMutator.couldNotDeserialize(PropertyMutator.java:56)
    at com.owlike.genson.reflect.PropertyMutator.deserialize(PropertyMutator.java:39)
    at com.owlike.genson.reflect.BeanDescriptor.deserialize(BeanDescriptor.java:116)
    at com.owlike.genson.reflect.BeanDescriptor.deserialize(BeanDescriptor.java:98)
    at com.owlike.genson.convert.NullConverter$NullConverterWrapper.deserialize(NullConverter.java:61)
    at com.owlike.genson.Genson.deserialize(Genson.java:452)
    at com.owlike.genson.ext.jaxrs.GensonJsonConverter.readFrom(GensonJsonConverter.java:125)
    ... 48 more
Caused by: com.owlike.genson.TransformationException: Could not parse date 1432800716000
    at com.owlike.genson.convert.DefaultConverters$DateConverter.deserialize(DefaultConverters.java:824)
    at com.owlike.genson.convert.DefaultConverters$DateConverter.deserialize(DefaultConverters.java:788)
    at com.owlike.genson.convert.NullConverter$NullConverterWrapper.deserialize(NullConverter.java:61)
    at com.owlike.genson.reflect.PropertyMutator.deserialize(PropertyMutator.java:37)
    ... 53 more
Caused by: java.text.ParseException: Unparseable date: "1432800716000"
    at java.text.DateFormat.parse(DateFormat.java:357)
    at com.owlike.genson.convert.DefaultConverters$DateConverter.read(DefaultConverters.java:830)
    at com.owlike.genson.convert.DefaultConverters$DateConverter.deserialize(DefaultConverters.java:822)
    ... 56 more

What's wrong?
PS Jersey client 1.8
Genson 0.98

Answer 1

You should upgrade to the latest Genson version, there have been some improvements and providing a custom instance to jersey is easier.

In the newer versions, Genson will automatically detect if the input is the time in millis or a date string and deser it accordingly.

The dateformat registered with useDateFormat(...) will be used during deserialization, but this will also serialize the dates as strings. If you want to serialize them as a long (which is the default in the newever versions), you have define it with useDateAsTimestamp(true).

I hope this makes things a bit more clear. You can have a look at the config options for more details.