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JSON 错误：无法构造类名的实例？

• 问答

当我试图通过邮递员使用 rest api 传递 json 请求时，我遇到了一个错误，这里是错误日志下方，我很想知道这里出了什么问题，我怀疑这是构造函数的问题，因为我知道我使用 AllArgsConstructor 和 NoArgsConstructor 注释编写了所有参数构造函数和默认构造函数，或者我在某处遗漏了一些注释，但老实说我不确定我哪里出错了。


2021-07-30 14:46:04.363 ERROR 7576 --- [nio-8080-exec-6] o.s.d.r.w.RepositoryRestExceptionHandler : JSON parse error: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/1'); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/1')
 at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 5,column: 17] (through reference chain: org.sid.cinema.entities.Film["categorie"])

org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/1'); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/1')
 at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 5,column: 17] (through reference chain: org.sid.cinema.entities.Film["categorie"])
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:389) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readInternal(AbstractJackson2HttpMessageConverter.java:350) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.http.converter.AbstractHttpMessageConverter.read(AbstractHttpMessageConverter.java:199) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.read(PersistentEntityResourceHandlerMethodArgumentResolver.java:246) ~[spring-data-rest-webmvc-3.5.2.jar:3.5.2]
    at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.lambda$read$6(PersistentEntityResourceHandlerMethodArgumentResolver.java:202) ~[spring-data-rest-webmvc-3.5.2.jar:3.5.2]
    at java.util.Optional.orElseGet(Optional.java:267) ~[na:1.8.0_191]
    at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.read(PersistentEntityResourceHandlerMethodArgumentResolver.java:202) ~[spring-data-rest-webmvc-3.5.2.jar:3.5.2]
    at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.resolveArgument(PersistentEntityResourceHandlerMethodArgumentResolver.java:132) ~[spring-data-rest-webmvc-3.5.2.jar:3.5.2]
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentvalues(InvocableHandlerMethod.java:170) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1063) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) [spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) [spring-webmvc-5.3.8.jar:5.3.8]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:681) [tomcat-embed-core-9.0.48.jar:4.0.FR]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) [spring-webmvc-5.3.8.jar:5.3.8]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) [tomcat-embed-core-9.0.48.jar:4.0.FR]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:228) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) [spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.8.jar:5.3.8]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) [spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.8.jar:5.3.8]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) [spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.8.jar:5.3.8]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1723) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_191]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_191]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191]
Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/1')
 at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 5,column: 17] (through reference chain: org.sid.cinema.entities.Film["categorie"])
    at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:63) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1588) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1213) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.std.StdDeserializer._deserializeFromString(StdDeserializer.java:311) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromString(BeanDeserializerBase.java:1495) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:207) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:197) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:129) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:402) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:195) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootvalue(DefaultDeserializationContext.java:322) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4593) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3601) ~[jackson-databind-2.12.3.jar:2.12.3]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:378) ~[spring-web-5.3.8.jar:5.3.8]
    ... 54 common frames omitted

2021-07-30 14:46:04.415  WARN 7576 --- [nio-8080-exec-6] .m.m.a.ExceptionHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/1'); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/1')
 at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 5,column: 17] (through reference chain: org.sid.cinema.entities.Film["categorie"])]
2021-07-30 16:16:53.003  WARN 7576 --- [nio-8080-exec-2] tion$ResourceSupportHttpMessageConverter : Failed to evaluate Jackson deserialization for type [[simple type,class org.springframework.data.rest.webmvc.PersistentEntityResource]]: java.lang.NullPointerException
2021-07-30 16:21:05.694  WARN 7576 --- [nio-8080-exec-8] tion$ResourceSupportHttpMessageConverter : Failed to evaluate Jackson deserialization for type [[simple type,class org.springframework.data.rest.webmvc.PersistentEntityResource]]: java.lang.NullPointerException
2021-07-30 16:21:06.306 ERROR 7576 --- [nio-8080-exec-8] o.s.d.r.w.RepositoryRestExceptionHandler : JSON parse error: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/2'); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/2')
 at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 5,column: 17] (through reference chain: org.sid.cinema.entities.Film["categorie"])

org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/2'); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/2')
 at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 5,column: 17] (through reference chain: org.sid.cinema.entities.Film["categorie"])
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:389) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readInternal(AbstractJackson2HttpMessageConverter.java:350) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.http.converter.AbstractHttpMessageConverter.read(AbstractHttpMessageConverter.java:199) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.read(PersistentEntityResourceHandlerMethodArgumentResolver.java:246) ~[spring-data-rest-webmvc-3.5.2.jar:3.5.2]
    at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.lambda$read$6(PersistentEntityResourceHandlerMethodArgumentResolver.java:202) ~[spring-data-rest-webmvc-3.5.2.jar:3.5.2]
    at java.util.Optional.orElseGet(Optional.java:267) ~[na:1.8.0_191]
    at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.read(PersistentEntityResourceHandlerMethodArgumentResolver.java:202) ~[spring-data-rest-webmvc-3.5.2.jar:3.5.2]
    at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.resolveArgument(PersistentEntityResourceHandlerMethodArgumentResolver.java:132) ~[spring-data-rest-webmvc-3.5.2.jar:3.5.2]
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentvalues(InvocableHandlerMethod.java:170) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) ~[spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1063) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) [spring-webmvc-5.3.8.jar:5.3.8]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) [spring-webmvc-5.3.8.jar:5.3.8]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:681) [tomcat-embed-core-9.0.48.jar:4.0.FR]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) [spring-webmvc-5.3.8.jar:5.3.8]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) [tomcat-embed-core-9.0.48.jar:4.0.FR]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:228) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) [spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.8.jar:5.3.8]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) [spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.8.jar:5.3.8]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) [spring-web-5.3.8.jar:5.3.8]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.8.jar:5.3.8]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1723) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_191]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_191]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.48.jar:9.0.48]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191]
Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `org.sid.cinema.entities.Categorie` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/categories/2')
 at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 5,column: 17] (through reference chain: org.sid.cinema.entities.Film["categorie"])
    at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:63) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1588) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1213) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.std.StdDeserializer._deserializeFromString(StdDeserializer.java:311) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromString(BeanDeserializerBase.java:1495) ~[jackson-databind-2.12.3.jar:2.12.3]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:207) ~[jackson-databind-2.12.3.jar:2.12.3]

这是我在 postman 中使用这个 url 作为 json 请求编写的内容：http://localhost:8080/films 使用 post 方法

{
   "titre": "my titre8","description": "my descr8","realisateur": "realisateur8","categorie":"http://localhost:8080/categories/1"
   
}

这里是电影课

package org.sid.cinema.entities;

import java.util.Collection;
import java.util.Date;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
@Entity
@Data @AllArgsConstructor @NoArgsConstructor @ToString
public class Film {
    @Id @GeneratedValue(strategy= GenerationType.IDENTITY)
    private Long id;
    private String titre;
    private String description;
    private String realisateur;
    private Date dateSortie;
    private double duree;
    private String photo;
    @OneToMany(mappedBy="film")
    private Collection<Projection> projections;
    @ManyToOne
    private Categorie categorie;
    

}

这里是分类类

package org.sid.cinema.entities;

import java.util.Collection;
import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
@Entity
@Data @AllArgsConstructor @NoArgsConstructor @ToString
public class Categorie {
    @Id @GeneratedValue(strategy= GenerationType.IDENTITY)
    private Long id;
    @Column(length=75) // par defaut length=255
    private String name ;
    @OneToMany(mappedBy="categorie")
    private Collection<Film> films;

}
hpsheng 回答：JSON 错误：无法构造类名的实例？

您的 json 请求正在尝试将 Categorie 编写为 String

{
   "titre": "my titre8","description": "my descr8","realisateur": "realisateur8","categorie":"http://localhost:8080/categories/1"
   
}
---

"categorie":"http://localhost:8080/categories/1"

当您拍摄时，班级希望 Catagorie 成为班级。

public class Film {
    @Id @GeneratedValue(strategy= GenerationType.IDENTITY)
    private Long id;
    private String titre;
    private String description;
    private String realisateur;
    private Date dateSortie;
    private double duree;
    private String photo;
    @OneToMany(mappedBy="film")
    private Collection<Projection> projections;
    @ManyToOne
    private Categorie categorie;
   
}

您可以在 json 请求中以 Catagorie 的形式传递一个 json 对象，也可以添加一个它可以使用的字符串参数构造函数。

org.sid.cinema.entities.Categorie (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value

创建一个接受字符串的构造函数

public class Catagorie {

    public Catagorie(String initStringUrl) {
     // handle url
}
}
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