java - 如何在 Jersey 客户端中默认使用 Genson 提供程序？

Question

我有一个基于 Jersey 框架的简单客户端。
我想使用 Genson 作为默认的 JSON 提供程序。
首先，我创建了一些实现了 ContextResolver 的类:

@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;
    }
}

和 UtcDateFormat 类:

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));
    }
}

然后我用了这个:

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);

但是，它失败了。这是日志:

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

怎么了？
附言泽西客户端 1.8
根森0.98

Answer 1

你应该升级到最新的 Genson 版本，有一些改进和 providing a custom instance到 Jersey 更容易。

在较新的版本中，Genson 会自动检测输入的是以毫秒为单位的时间还是日期字符串，并相应地对其进行反序列化。

在反序列化期间将使用使用 useDateFormat(...) 注册的日期格式，但这也会将日期序列化为字符串。如果你想将它们序列化为 long(这是新版本中的默认设置)，你已经用 useDateAsTimestamp(true) 定义了它。

我希望这能让事情变得更清楚一些。你可以看看the config options了解更多详情。