java - JSON 字符串到对象列表

Question

我收到了以下 JSON 字符串。我尝试使用此处给定的代码将字符串转换为对象列表。

JSON 字符串

{"hotelPromotions":[{"id":728,"version":1,"description":"Testing Discount","status":"ACTIVE","user":"MAHESHR","hotelId":245,"fromDate":1420070400000,"toDate":1420848000000,"hotelRoomTypeId":null,"travelAgentId":null,"roomTypeIds":[1138,1143,1137,1139,1140],"firstContractId":null,"secondContractId":null,"hotelIdTemp":null,"rateCategoryIds":[248],"ratePlanIds":[2108],"promotionType":"FREE_NIGHT","reservationInAdvanceValue":0,"reservationInAdvanceType":null,"noOfNights":2,"freeNights":1,"promotionAvailableDate":null,"discount":0,"availableMon":1,"availableTue":1,"availableWed":1,"availableThu":1,"availableFri":1,"availableSat":1,"availableSun":1,"reservationId":null,"multipleNights":"NO","resCreatedDate":null}],"hotelIBEDiscounts":[{"id":461,"version":1,"description":"nsg coupon","status":"ACTIVE","user":"MAHESHR","hotelId":245,"fromDate":1414627200000,"toDate":1419984000000,"hotelName":"The Wallawwa","roomTypeIds":[1138,1143],"rateCategoryIds":[248],"ratePlanIds":[],"discount":20,"availableMon":1,"availableTue":1,"availableWed":1,"availableThu":1,"availableFri":1,"availableSat":1,"availableSun":1,"discountType":"COUPONS","noOfCoupons":"10","couponsType":"UNIQUE"}]}

转化码

    List<HotelPromotionDTO> hotelPromotionDTOs = new ArrayList<HotelPromotionDTO>();
    ParameterSupport parameterSupport = externalConnector.getCrsParameters();   

    //Get Server IP from Parameters
    String serverIp = parameterSupport.getParam(CRSEntryParameterConstants.EXTERNAL_URL);;

    String url = ApplicationWebURLConstants.HTTP_URL+""+serverIp+"/"+ApplicationWebURLConstants.GET_HOTEL_PROMO_AND_DISC_BY_DATES;

    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.configure(SerializationFeature.INDENT_OUTPUT, true);
    StringWriter stringEmp = new StringWriter();
    final DateFormat df = new SimpleDateFormat(DateConstants.JSON_DATE_FORMAT);
    objectMapper.setDateFormat(df);

    try {
        objectMapper.writeValue(stringEmp, searchCriteria);
    } catch (JsonGenerationException e) {
        LOG.error("JsonGenerationException :::: ",e);
    } catch (JsonMappingException e) {
        LOG.error("JsonMappingException :::: ",e);
    } catch (IOException e) {
        LOG.error("IOException :::: ",e);
    }

    String jsonString = stringEmp.toString();
    ClientResponse response = WebServiceUtil.postRequest(url, jsonString);
    String output = response.getEntity(String.class);

    //DeSerialization of response data to IBEDiscountCouponValidateResultDTO type
    objectMapper = new ObjectMapper();
    objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    try {
        hotelPromotionDTOs = objectMapper.readValue(output, objectMapper.getTypeFactory().constructCollectionType(List.class, HotelPromotionDTO.class));
    } catch (JsonParseException e) {
        LOG.error("JsonParseException on Deserialization :::: ",e);
    } catch (JsonMappingException e) {
        LOG.error("JsonMappingException on Deserialization :::: ",e);
    } catch (IOException e) {
        LOG.error("IOException on Deserialization :::: ",e);
    }

    return hotelPromotionDTOs;

当我执行代码时，出现以下错误。

2014-12-30 06:27:11,527 ERROR [com.jkcs.zhara.ext.integration.client.impl.ApplicationConnectorZharaImpl] (http-8647-6:)     JsonMappingException on Deserialization :::: 
com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
at [Source: java.io.StringReader@6343b54; line: 1, column: 1]
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:164)
    at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:691)
    at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:685)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.handleNonArray(CollectionDeserializer.java:256)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:214)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:204)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:23)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2986)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2105)
    at com.jkcs.zhara.ext.integration.client.impl.ApplicationConnectorZharaImpl.findHotelPromoAndDiscForIBEByCriteria(ApplicationConnectorZharaImpl.java:489)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:80)
    at com.jkcs.zhara.service.platform.aspects.ServiceProfilerAspect.profile(ServiceProfilerAspect.java:56)
    at sun.reflect.GeneratedMethodAccessor101.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610)
    at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:55)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    at $Proxy128.findHotelPromoAndDiscForIBEByCriteria(Unknown Source)
    at com.jkcs.zhara.ext.integration.client.ApplicationConnectorFactoryServiceImpl.findHotelPromoAndDiscForIBEByCriteria(ApplicationConnectorFactoryServiceImpl.java:84)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:80)
    at com.jkcs.zhara.service.platform.aspects.ServiceProfilerAspect.profile(ServiceProfilerAspect.java:56)
    at sun.reflect.GeneratedMethodAccessor101.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610)
    at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:55)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    at $Proxy129.findHotelPromoAndDiscForIBEByCriteria(Unknown Source)
    at com.jkcs.zhara.service.booking.internal.impl.BookingInternalServiceImpl.getAllHotelDataOnLoad(BookingInternalServiceImpl.java:263)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:80)
    at com.jkcs.zhara.service.platform.aspects.ServiceProfilerAspect.profile(ServiceProfilerAspect.java:56)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610)
    at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:55)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    at $Proxy131.getAllHotelDataOnLoad(Unknown Source)
    at com.jkcs.zhara.service.booking.ejb.impl.BookingServiceBean.getAllHotelDataOnLoad(BookingServiceBean.java:48)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:112)
    at org.jboss.ejb3.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:166)
    at org.jboss.ejb3.interceptor.EJB3InterceptorsInterceptor.invoke(EJB3InterceptorsInterceptor.java:63)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
    at org.jboss.ejb3.entity.TransactionScopedEntityManagerInterceptor.invoke(TransactionScopedEntityManagerInterceptor.java:54)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
    at org.jboss.ejb3.AllowedOperationsInterceptor.invoke(AllowedOperationsInterceptor.java:47)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
    at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:79)
    at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:191)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
    at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:95)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
    at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:62)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
    at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:77)
    at org.jboss.ejb3.security.Ejb3AuthenticationInterceptor.invoke(Ejb3AuthenticationInterceptor.java:110)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
    at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:46)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
    at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
    at org.jboss.ejb3.stateless.StatelessContainer.localInvoke(StatelessContainer.java:240)
    at org.jboss.ejb3.stateless.StatelessContainer.localInvoke(StatelessContainer.java:210)
    at org.jboss.ejb3.stateless.StatelessLocalProxy.invoke(StatelessLocalProxy.java:84)
    at $Proxy73.getAllHotelDataOnLoad(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.ejb.access.LocalSlsbInvokerInterceptor.invokeInContext(LocalSlsbInvokerInterceptor.java:71)
    at org.springframework.ejb.access.AbstractSlsbInvokerInterceptor.invoke(AbstractSlsbInvokerInterceptor.java:189)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    at $Proxy117.getAllHotelDataOnLoad(Unknown Source)
    at com.jkcs.zhara.web.booking.BookingController.getLandingPage(BookingController.java:205)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:920)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:816)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:801)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:182)
    at org.jboss.web.tomcat.service.session.ClusteredSessionValve.invoke(ClusteredSessionValve.java:97)
    at org.jboss.web.tomcat.service.session.JvmRouteValve.invoke(JvmRouteValve.java:84)
    at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
    at org.jboss.web.tomcat.service.sso.ClusteredSingleSignOn.invoke(ClusteredSingleSignOn.java:638)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)
    at java.lang.Thread.run(Thread.java:662)

我尝试使用 TypeReference 解决方案，但它也给了我上述异常。如果有人能识别出我正在做的错误，那将是一个很大的帮助!

Answer 1

您的 JSON 匹配一个对象(参见下面的 HotelPromotionList)，而不是列表。

class HotelPromotionList {
   List<HotelPromotion> hotelPromotions;
}

class HotelPromotion {
   int id;
   int version;
   String description;
   String status; // might be an enum
   // ...
}