我有一个使用 Jersey 2.6 框架运行 servlet 的 Tomcat 服务器。在 servlet 中，我将 Jackson 用于 JSON POJO 编码。我最近了解到 Moxy 并正在尝试改用它，因为 Jersey 似乎更喜欢它。
目前，我的 POM 中有以下内容:
<dependency>
<groupId>org.glassfish.jersey.media</groupId>
<artifactId>jersey-media-moxy</artifactId>
<version>2.6</version>
</dependency>
我的 RESTful 服务之一如下:
@GET
@Path("threatSeverities")
@Produces(MediaType.APPLICATION_JSON)
public List<String> getThreatSeverities() {
return dc.selectAllSeverities();
}
这与 jackson 一起工作得很好。当我改为 Moxy 时，单元测试如下:
@Test
public void testThreatSeverities() {
final Response response = target("threatSeverities").request().get();
List<String> severities = response.readEntity(new GenericType<List<String>> () {});
assertNotNull(severities);
}
会产生以下错误:
org.glassfish.jersey.message.internal.MessageBodyProviderNotFoundException: MessageBodyReader not found for media type=text/plain, type=interface java.util.List, genericType=java.util.List<java.lang.String>.
at org.glassfish.jersey.message.internal.ReaderInterceptorExecutor$TerminalReaderInterceptor.aroundReadFrom(ReaderInterceptorExecutor.java:225)
at org.glassfish.jersey.message.internal.ReaderInterceptorExecutor.proceed(ReaderInterceptorExecutor.java:149)
at org.glassfish.jersey.message.internal.MessageBodyFactory.readFrom(MessageBodyFactory.java:1124)
at org.glassfish.jersey.message.internal.InboundMessageContext.readEntity(InboundMessageContext.java:853)
at org.glassfish.jersey.message.internal.InboundMessageContext.readEntity(InboundMessageContext.java:812)
at org.glassfish.jersey.client.ClientResponse.readEntity(ClientResponse.java:377)
at org.glassfish.jersey.client.InboundJaxrsResponse$2.call(InboundJaxrsResponse.java:122)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:228)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:398)
at org.glassfish.jersey.client.InboundJaxrsResponse.readEntity(InboundJaxrsResponse.java:119)
at com.hp.it.scv.mobile.rest.RestTest.testThreatSeverities(RestTest.java:85)
at (... truncated)
值得注意的是，即使 Controller 方法
getThreatSeverities 有一个 @Produces(MediaType.APPLICATION_JSON) ，似乎 Moxy(或其他我看不到的东西)正在更改单元测试中对 Content-Type 的响应的 text/plain header 。这一切都没有发生在 jackson 身上。还有一点要注意，这似乎是特定于
List<String> 对象的。 Moxy 可以毫无问题地整理 POJO 列表。List<String> 对象编码为 JSON 字符串？似乎答案是否定的。我在网上找不到结论性的答案。我想知道是否需要为 MessageBodyReader 对象编写自己的 MessageBodyWriter 和 List<String>。 Content-Type header 更改为 text/plain 吗？我怀疑它是 Moxy，也许是因为它看到我试图返回一个简单的字符串列表。 更新 (2/2/2015):
正如 peeskillet 所指出的，返回的响应是 HTTP 500。我能够从响应中提取堆栈跟踪，并得到以下信息:
Stack trace: javax.ws.rs.WebApplicationException: HTTP 500 Internal Server Error
at org.eclipse.persistence.jaxb.rs.MOXyJsonProvider.writeTo(MOXyJsonProvider.java:810)
at org.glassfish.jersey.message.internal.WriterInterceptorExecutor$TerminalWriterInterceptor.invokeWriteTo(WriterInterceptorExecutor.java:263)
at org.glassfish.jersey.message.internal.WriterInterceptorExecutor$TerminalWriterInterceptor.aroundWriteTo(WriterInterceptorExecutor.java:250)
at org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:162)
at org.glassfish.jersey.server.internal.JsonWithPaddingInterceptor.aroundWriteTo(JsonWithPaddingInterceptor.java:103)
at org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:162)
at org.glassfish.jersey.server.internal.MappableExceptionWrapperInterceptor.aroundWriteTo(MappableExceptionWrapperInterceptor.java:88)
at org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:162)
at org.glassfish.jersey.message.internal.MessageBodyFactory.writeTo(MessageBodyFactory.java:1154)
at org.glassfish.jersey.server.ServerRuntime$Responder.writeResponse(ServerRuntime.java:571)
at org.glassfish.jersey.server.ServerRuntime$Responder.processResponse(ServerRuntime.java:378)
at org.glassfish.jersey.server.ServerRuntime$Responder.process(ServerRuntime.java:368)
at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:262)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:319)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:236)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1028)
at org.glassfish.jersey.grizzly2.httpserver.GrizzlyHttpContainer.service(GrizzlyHttpContainer.java:363)
at org.glassfish.grizzly.http.server.HttpHandler$1.run(HttpHandler.java:217)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
at java.lang.Thread.run(Unknown Source)
Caused by: javax.xml.bind.MarshalException - with linked exception:
[Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: Exception [EclipseLink-25007] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: A descriptor for class java.lang.String was not found in the project. For JAXB, if the JAXBContext was bootstrapped using TypeMappingInfo[] you must call a marshal method that accepts TypeMappingInfo as an input parameter.]
at org.eclipse.persistence.jaxb.JAXBMarshaller.marshal(JAXBMarshaller.java:403)
at org.eclipse.persistence.jaxb.rs.MOXyJsonProvider.writeTo(MOXyJsonProvider.java:808)
... 25 more
Caused by: Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: Exception [EclipseLink-25007] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: A descriptor for class java.lang.String was not found in the project. For JAXB, if the JAXBContext was bootstrapped using TypeMappingInfo[] you must call a marshal method that accepts TypeMappingInfo as an input parameter.
at org.eclipse.persistence.exceptions.XMLMarshalException.marshalException(XMLMarshalException.java:97)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshal(XMLMarshaller.java:911)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshal(XMLMarshaller.java:848)
at org.eclipse.persistence.jaxb.JAXBMarshaller.marshal(JAXBMarshaller.java:401)
... 26 more
Caused by: Exception [EclipseLink-25007] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: A descriptor for class java.lang.String was not found in the project. For JAXB, if the JAXBContext was bootstrapped using TypeMappingInfo[] you must call a marshal method that accepts TypeMappingInfo as an input parameter.
at org.eclipse.persistence.exceptions.XMLMarshalException.descriptorNotFoundInProject(XMLMarshalException.java:139)
at org.eclipse.persistence.internal.oxm.Context$ContextState.getSession(Context.java:143)
at org.eclipse.persistence.oxm.XMLContext$XMLContextState.getSession(XMLContext.java:787)
at org.eclipse.persistence.oxm.XMLContext$XMLContextState.getSession(XMLContext.java:1)
at org.eclipse.persistence.internal.oxm.Context.getSession(Context.java:451)
at org.eclipse.persistence.oxm.XMLContext.getSession(XMLContext.java:356)
at org.eclipse.persistence.oxm.XMLContext.getSession(XMLContext.java:1)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshal(XMLMarshaller.java:568)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshal(XMLMarshaller.java:1096)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshal(XMLMarshaller.java:869)
... 28 more
从
Exception Description: A descriptor for class java.lang.String was not found in the project. 看来，如果不手动编码某些东西，List<String> 到 JSON 编码是不可能的。 最佳答案
MOXy 代码( moxy/org.eclipse.persistence.moxy/src/org/eclipse/persistence/jaxb/rs/MOXyJsonProvider.java )中有一些不明确的限制，这阻止了它处理“java.*”类的集合。我已经提出了反对这个问题。
https://bugs.eclipse.org/bugs/show_bug.cgi?id=459227
关于java - Moxy 无法将 List<String> 编码为 JSON，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/28223172/