Spring启动REST服务：JSON反序列化不起作用
我正在使用spring-boot和Kotlin开发一个REST服务。 （我应该提到这是我第一次同时使用）。我无法让杰克逊使用此代码从POST请求反序列化JSON：
@RequestMapping("cloudservice/login/{uuid}", method = arrayOf(RequestMethod.POST)) fun login(@PathVariable(value="uuid")uuid: String, @RequestBody user: CloudServiceUser ) : ResponseEntity<CloudServiceUser> { val cloudServiceFactory : Class<CloudServiceFactory> = cloudServiceRepository.cloudServiceExtensions[UUID.fromString(uuid)] ?: throw InvalidPathVariableException("Invalid UUID.") var token : String try { token = cloudServiceFactory.newInstance().authenticationService.login(user.userId, user.password) } catch (e:Exception ){ throw CloudServiceException(e.message) } return ResponseEntity(CloudServiceUser(userId=user.userId, password = "", token = token),HttpStatus.OK) } 用户对象很简单：
data class CloudServiceUser(val userId: String, val password:String, val token:String)
我得到错误
org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Can not construct instance of com.irotsoma.cloudbackenc.cloudservice.CloudServiceUser: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?) at [Source: java.io.PushbackInputStream@682b15d6; line: 1, column: 2]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.irotsoma.cloudbackenc.cloudservice.CloudServiceUser: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?) at [Source: java.io.PushbackInputStream@682b15d6; line: 1, column: 2] at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:229) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:213) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:197) ~[spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:147) ~[spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:125) ~[spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:99) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:161) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) [spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:832) [spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:743) [spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) [spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:961) [spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895) [spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967) [spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:869) [spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:648) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843) [spring-webmvc-4.2.6.RELEASE.jar:4.2.6.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-embed-websocket-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:261) [spring-boot-actuator-1.3.5.RELEASE.jar:1.3.5.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:115) [spring-boot-actuator-1.3.5.RELEASE.jar:1.3.5.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) [spring-boot-actuator-1.3.5.RELEASE.jar:1.3.5.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1502) [tomcat-embed-core-8.0.33.jar:8.0.33] at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1458) [tomcat-embed-core-8.0.33.jar:8.0.33] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_92] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_92] at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.0.33.jar:8.0.33] at java.lang.Thread.run(Thread.java:745) [na:1.8.0_92] Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.irotsoma.cloudbackenc.cloudservice.CloudServiceUser: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?) at [Source: java.io.PushbackInputStream@682b15d6; line: 1, column: 2] at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:261) ~[jackson-databind-2.8.0.jar:2.8.0] at com.fasterxml.jackson.databind.DeserializationContext.instantiationException(DeserializationContext.java:1420) ~[jackson-databind-2.8.0.jar:2.8.0] at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1011) ~[jackson-databind-2.8.0.jar:2.8.0] at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1201) ~[jackson-databind-2.8.0.jar:2.8.0] at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:314) ~[jackson-databind-2.8.0.jar:2.8.0] at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:148) ~[jackson-databind-2.8.0.jar:2.8.0] at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3789) ~[jackson-databind-2.8.0.jar:2.8.0] at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2913) ~[jackson-databind-2.8.0.jar:2.8.0] at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:226) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE] ... 66 common frames omitted
但是，在return语句中的序列化工作很好，可以序列化为一个JSON对象并发送响应。 这只是反序列化不起作用。
如果我将主体变量更改为一个字符串，并手动创建映射器，它也可以正常工作。 喜欢这个：
@RequestMapping("cloudservice/login/{uuid}", method = arrayOf(RequestMethod.POST)) fun login(@PathVariable(value="uuid")uuid: String, @RequestBody user: String ) : ResponseEntity<CloudServiceUser> { val mapper = ObjectMapper().registerModule(KotlinModule()) val mapperData: CloudServiceUser = mapper.readValue(user) val cloudServiceFactory : Class<CloudServiceFactory> = cloudServiceRepository.cloudServiceExtensions[UUID.fromString(uuid)] ?: throw InvalidPathVariableException("Invalid UUID.") var token : String try { token = cloudServiceFactory.newInstance().authenticationService.login(mapperData.userId, mapperData.password) } catch (e:Exception ){ throw CloudServiceException(e.message) } return ResponseEntity(CloudServiceUser(userId=mapperData.userId, password = "", token = token),HttpStatus.OK) }
有任何想法吗？
这是一个开源项目，如果您需要更多信息，请随时浏览： https ： //github.com/irotsoma/cloudbackenc 。 请注意，目前它处于非常早期的状态。
编辑：只是想添加一个笔记关于我的麻烦与集成测试注释在接受的答案评论。 我最终没有得到集成测试能够反序列化响应（尽管REST控制器方面的工作很好，就像在生产中一样）。 所以我找到了一个使用Map对象的解决方法，出于某种原因，它能够反序列化，然后手动处理它，而不是使用类对象。 既然这只是测试的问题而不是被测试的代码，这对我来说很好。
val returnValue = template.postForEntity("REQUEST URL", httpEntity, Map::class.java)
您需要帮助杰克逊反序列化错误消息中指出的数据类。 你可以通过在ObjectMapper注册jackson-module-kotlin来这样做：
val mapper = ObjectMapper().registerModule(KotlinModule())
要告诉Spring你自己定制的ObjectMapper 定义一个@Bean并将其标记为@Primary ：
@Configuration open class ObjectMapperConfiguration { @Bean @Primary open fun objectMapper() = ObjectMapper().apply { registerModule(KotlinModule()) } }
进一步阅读：
- 如何使用杰克逊反序列化Kotlin集合
- 如何使用Kotlin + Jackson将JSON反序列化为List <SomeType>