1

我在使用 JacksonMapper 在 JSON 对象处返回 Java 类时遇到此异常。

org.codehaus.jackson.map.JsonMappingException: No serializer found for class $Proxy57 and properties found to create BeanSerializer (为避免异常，禁用 SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS) ）（通过参考链：java.util.HashMap["exception "]->org.springframework.core.convert.ConversionFailedException["targetType"]->org.springframework.core.convert.TypeDescriptor["annotations"])

at org.codehaus.jackson.map.ser.StdSerializerProvider$1.serialize(StdSerializerProvider.java:55)

at org.codehaus.jackson.map.ser.ArraySerializers$ObjectArraySerializer.serialize(ArraySerializers.java:66)

at org.codehaus.jackson.map.ser.ArraySerializers$ObjectArraySerializer.serialize(ArraySerializers.java:35)

at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:218)

at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:122)

at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:218)

at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:122)

at org.codehaus.jackson.map.ser.MapSerializer.serializeEntries(MapSerializer.java:131)

at org.codehaus.jackson.map.ser.MapSerializer.serialize(MapSerializer.java:74)

at org.codehaus.jackson.map.ser.MapSerializer.serialize(MapSerializer.java:19)

at org.codehaus.jackson.map.ser.StdSerializerProvider._serializeValue(StdSerializerProvider.java:260)

at org.codehaus.jackson.map.ser.StdSerializerProvider.serializeValue(StdSerializerProvider.java:212)

at org.codehaus.jackson.map.ObjectMapper.writeValue(ObjectMapper.java:694)

at org.springframework.web.servlet.view.json.MappingJacksonJsonView.renderMergedOutputModel(MappingJacksonJsonView.java:151)

at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250)

at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1063)

at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:801)

at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)

at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)

at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at com.opensymphony.sitemesh.webapp.SiteMeshFilter.obtainContent(SiteMeshFilter.java:129)

at com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:77)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:343)

at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)

at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.oauth.provider.OAuthProviderProcessingFilter.doFilter(OAuthProviderProcessingFilter.java:173)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.oauth.provider.OAuthProviderProcessingFilter.doFilter(OAuthProviderProcessingFilter.java:193)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:187)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.oauth.provider.OAuthProviderProcessingFilter.doFilter(OAuthProviderProcessingFilter.java:193)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:112)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:177)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:187)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.session.ConcurrentSessionFilter.doFilter(ConcurrentSessionFilter.java:109)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.access.channel.ChannelProcessingFilter.doFilter(ChannelProcessingFilter.java:109)

at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)

at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:149)

at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)

at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:206)

at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:179)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
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:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:776)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:705)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:898)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
at java.lang.Thread.run(Thread.java:662)

我想知道 Spring 创建了哪个类 $Proxy57 对象，以便我可以调试我的代码，而且我在服务器上发现这个错误也非常罕见。所以我没有得到正确的原因。此异常有时会导致我的服务器崩溃。

提前致谢，

4

1 回答 1

2

当您使用 ORM 时，它会根据您持久保存的对象创建代理对象。这样，它可以通过该代理延迟加载（即，仅在需要时加载）信息。Jackson 不知道如何序列化这些代理，只是普通的 POJO。通常，当您将对象传递给 jackson 时，ORM 会话已经关闭并且延迟加载尝试失败。我确信您尝试序列化 ORM 代理对象的事实是您的问题的根本原因。

一种解决方案是在 ORM 中禁用延迟加载。当然，您将失去延迟加载带来的所有好处。仔细考虑您延迟加载的内容和不加载的内容（如果您使用我强烈建议的 JPA，请明确注释您的 POJO 关系）。

另一种解决方案是编写一个自定义的 Jackson 序列化程序，它知道如何序列化这些对象。

我在使用 hibernate 时遇到了同样的问题，这个小模块就是这样做的：我的 Jackson 现在序列化 Hibernate 特定的对象和数据类型。

于 2013-01-15T10:24:57.510 回答