Spring Rest – exception生成Json数据
我有一个我希望通过json rest调用公开的值对象。 我在我的项目中有许多其他的rest调用工作得很好，但这1并不是出于某种原因。 当我尝试将这个对象返回时 – 我得到一个例外，我不知道如何解决
值对象代码如下（减去访问器方法）
package com.test.domain.dao; import java.io.Serializable; import java.util.HashSet; import java.util.Set; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToMany; import javax.persistence.Table; import org.hibernate.annotations.Cascade; import org.hibernate.annotations.CascadeType; import com.fasterxml.jackson.annotation.JsonIgnore; @Entity @Table(name = "company") public class CompanyVO extends BaseDAOVO implements Serializable{ /** * */ private static final long serialVersionUID = 4278014816235716721L; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id", unique = true, nullable = false) private Integer id; @Column(name = "companyName", unique = true, nullable = false, length = 200) private String companyName; @Column(name = "companyLogo", unique = true, nullable = false, length = 10000) private String companyLogo; @Column(name = "isDefaultCompany",nullable = false) private boolean isDefaultCompany; @OneToMany(fetch = FetchType.LAZY, mappedBy = "company") @Cascade({ CascadeType.DELETE, CascadeType.SAVE_UPDATE }) @JsonIgnore private Set users = new HashSet(0); } 我通过json返回公司对象的rest方法如下
/** * Method to get the company for a particular userId * @param userId * @return */ @RequestMapping(value = { GET_COMPANY_FOR_USER }, method = RequestMethod.GET) public CompanyVO getCompanyForUser( @PathVariable(value = RestConstants.USER_ID_PLACEHOLDER) Integer userId) { LOG.info("Entered getCompanyForUser method - userId:{}", userId); CompanyVO companyVO = companyServices.getCompanyForUser(userId); LOG.info("Exiting getCompanyForUser method"); return companyVO; }
当我调用这个特殊的rest方法时，我在stacktrace中得到以下错误
[2015-03-02 11:12:30,229] [http-bio-8080-exec-8] [INFO] com.test.webapp.controllers.rest.CompanyRestController - Entered getCompanyForUser method - userId:1 [2015-03-02 11:12:30,248] [http-bio-8080-exec-8] [INFO] com.test.webapp.controllers.rest.CompanyRestController - Exiting getCompanyForUser method [2015-03-02 11:12:30,267] [http-bio-8080-exec-8] [INFO] ctwebapp.controllers.exceptions.GlobalExceptionHandlerController - Entered exception method: e:{} org.springframework.http.converter.HttpMessageNotWritableException: Could not write content: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.test.domain.dao.CompanyVO_$$_jvstb99_6["handler"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.test.domain.dao.CompanyVO_$$_jvstb99_6["handler"]) at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:238) ~[spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:208) ~[spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:161) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:101) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:202) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:71) ~[spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:126) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:777) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:706) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966) [spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857) [spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:620) [servlet-api.jar:na] at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842) [spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) [servlet-api.jar:na] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) [catalina.jar:7.0.54] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54] at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat7-websocket.jar:7.0.54] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.54] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54] at org.springframework.orm.hibernate4.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:150) [spring-orm-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.54] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54] at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:186) [spring-security-web-3.2.5.RELEASE.jar:3.2.5.RELEASE] at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) [spring-security-web-3.2.5.RELEASE.jar:3.2.5.RELEASE] at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.54] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54] at org.springframework.web.multipart.support.MultipartFilter.doFilterInternal(MultipartFilter.java:118) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.54] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) [catalina.jar:7.0.54] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) [catalina.jar:7.0.54] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501) [catalina.jar:7.0.54] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) [catalina.jar:7.0.54] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [catalina.jar:7.0.54] at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) [catalina.jar:7.0.54] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) [catalina.jar:7.0.54] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) [catalina.jar:7.0.54] at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040) [tomcat-coyote.jar:7.0.54] at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607) [tomcat-coyote.jar:7.0.54] at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316) [tomcat-coyote.jar:7.0.54] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_40] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_40] at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-coyote.jar:7.0.54] at java.lang.Thread.run(Thread.java:724) [na:1.7.0_40] Caused by: com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.test.domain.dao.CompanyVO_$$_jvstb99_6["handler"]) at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:59) ~[jackson-databind-2.4.3.jar:2.4.3] at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:26) ~[jackson-databind-2.4.3.jar:2.4.3] at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:505) ~[jackson-databind-2.4.3.jar:2.4.3] at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:639) ~[jackson-databind-2.4.3.jar:2.4.3] at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152) ~[jackson-databind-2.4.3.jar:2.4.3] at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:114) ~[jackson-databind-2.4.3.jar:2.4.3] at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:1887) ~[jackson-databind-2.4.3.jar:2.4.3] at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:231) ~[spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE] ... 50 common frames omitted
任何有关排序的帮助将非常感激
除了您已经找到的解决方案之外，您还可以考虑另外两种解决方案。 一个用ObjectMapper注册Hibernate4Module ，它将注册HibernateProxySerializer ，已经配备了处理代理的智能，你可以检查代码不难理解。 注册也很简单，形成他们的文档：
public class HibernateAwareObjectMapper extends ObjectMapper { public HibernateAwareObjectMapper() { registerModule(new Hibernate4Module()); } }
比登记
另一个解决方案是使用DTO对象，在从实体复制值时添加一些样板代码，但是为您提供更多控制并将表示与实际实体分离
根据masterSlave提供的链接和解决方案，我采用它来Spring Boot。 我在Spring Boot项目中遇到问题并解决它来创建HibernateAwareObjectMapper并定义一个自定义的新MappingJackson2HttpMessageConverter如下所示。
首先将hibernate4的dependecy添加到pom.xml
com.fasterxml.jackson.datatype jackson-datatype-hibernate4 2.5.3
创建HibernateAwareObjectMapper类
/** * https://github.com/FasterXML/jackson-datatype-hibernate * */ public class HibernateAwareObjectMapper extends ObjectMapper { /** * */ private static final long serialVersionUID = 1L; public HibernateAwareObjectMapper() { registerModule(new Hibernate4Module()); } }
将自定义MappingJackson2HttpMessageConverter类添加到Application.java
@Bean public MappingJackson2HttpMessageConverter customJackson2HttpMessageConverter() { MappingJackson2HttpMessageConverter jsonConverter = new MappingJackson2HttpMessageConverter(); HibernateAwareObjectMapper hibernateAwareObjectMapper = new HibernateAwareObjectMapper(); jsonConverter.setObjectMapper(hibernateAwareObjectMapper); return jsonConverter; } @Override public void configureMessageConverters(List> converters) { converters.add(customJackson2HttpMessageConverter()); super.addDefaultHttpMessageConverters(converters); }
感谢Evgeni提供的链接包含答案使用以下注释注释我的CompanyVO bean删除了错误@JsonIgnoreProperties（{“hibernateLazyInitializer”，“handler”}）