解決Jackson報錯：can not access a member of class xx.xx.ser.std.NullSerializer with modifiers "private"
阿新 • • 發佈：2018-11-24
解決 Jackson 報錯：can not access a member of class com.fasterxml.jackson.databind.ser.std.NullSerializer with modifiers "private"
一、問題描述
1、在使用 ssm 框架，返回 json 資料時候，第一次會丟擲一個異常： " can not access a member of class ... NullSerializer with modifiers "private" "，再重新整理一次，就好了，正常返回json資料，對專案使用，影響不大。
2、異常資訊如下：
2018-09-12 11:32:12,532 ERROR [500.jsp] - Could not write JSON: Failed to instantiate standard serializer (of type com.fasterxml.jackson.databind.ser.std.NullSerializer): Class com.fasterxml.jackson.databind.ser.BasicSerializerFactory can not access a member of class com.fasterxml.jackson.databind.ser.std.NullSerializer with modifiers "private" (through reference chain: java.util.ArrayList[0]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Failed to instantiate standard serializer (of type com.fasterxml.jackson.databind.ser.std.NullSerializer): Class com.fasterxml.jackson.databind.ser.BasicSerializerFactory can not access a member of class com.fasterxml.jackson.databind.ser.std.NullSerializer with modifiers "private" (through reference chain: java.util.ArrayList[0]) org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Failed to instantiate standard serializer (of type com.fasterxml.jackson.databind.ser.std.NullSerializer): Class com.fasterxml.jackson.databind.ser.BasicSerializerFactory can not access a member of class com.fasterxml.jackson.databind.ser.std.NullSerializer with modifiers "private" (through reference chain: java.util.ArrayList[0]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Failed to instantiate standard serializer (of type com.fasterxml.jackson.databind.ser.std.NullSerializer): Class com.fasterxml.jackson.databind.ser.BasicSerializerFactory can not access a member of class com.fasterxml.jackson.databind.ser.std.NullSerializer with modifiers "private" (through reference chain: java.util.ArrayList[0]) at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.writeInternal(MappingJackson2HttpMessageConverter.java:256) at org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:208) at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:143) at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:89) at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:188) at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:71) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863) at javax.servlet.http.HttpServlet.service(HttpServlet.java:650) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837) at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) 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:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449) at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365) at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90) at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83) at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383) at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362) at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:962) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1115) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745) Caused by: com.fasterxml.jackson.databind.JsonMappingException: Failed to instantiate standard serializer (of type com.fasterxml.jackson.databind.ser.std.NullSerializer): Class com.fasterxml.jackson.databind.ser.BasicSerializerFactory can not access a member of class com.fasterxml.jackson.databind.ser.std.NullSerializer with modifiers "private" (through reference chain: java.util.ArrayList[0]) at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:232) at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:211) at com.fasterxml.jackson.databind.ser.std.StdSerializer.wrapAndThrow(StdSerializer.java:210) at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:105) at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:21) at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:186) at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:118) at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:1819) at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.writeInternal(MappingJackson2HttpMessageConverter.java:253) ... 55 more Caused by: java.lang.IllegalStateException: Failed to instantiate standard serializer (of type com.fasterxml.jackson.databind.ser.std.NullSerializer): Class com.fasterxml.jackson.databind.ser.BasicSerializerFactory can not access a member of class com.fasterxml.jackson.databind.ser.std.NullSerializer with modifiers "private" at com.fasterxml.jackson.databind.ser.BasicSerializerFactory.findSerializerByLookup(BasicSerializerFactory.java:303) at com.fasterxml.jackson.databind.ser.BeanSerializerFactory._createSerializer2(BeanSerializerFactory.java:210) ... 此處省略 n 行 ...
3、後臺返回 json 資料程式碼：
@RequestMapping(value={"/getJson"})
@ResponseBody
public List<User> getJson(User user){
List<User> list = userService.getUserList(user);
return list;
}二、專案基本資訊
1、ssm 架構，spring 4.x.x
2、server Tomcat7
3、jackson-xx-2.2.3.jar （jackson 相關jar包版本 2.2.3 ）
三、問題解決
1、 升級 jackson 相關jar包，到 2.4.6 或以上，即可解決問題。
2、 已經驗證jackson相關 jar包，升級到2.5.0，不再出現 （一 - 1）中描述的異常資訊，問題解決。 jackson-annotations-2.5.0.jar ， jackson-core-2.5.0.jar，jackson-databind-2.5.0.jar 即可。
3、解決辦法引用這裡： https://github.com/FasterXML/jackson-databind/issues/851
4、若您不會下載jar包，點選 這裡 。
參考資料：