Welcher Jackson-Konverter wird verwendet, um eine Java-DataHandler-Klasse zu json zu marshallen?

Question

Ich habe eine Feder gemacht (Ich benutze Feder-Web 3) Rest Service. Ich habe diesen jackson Konverter in meiner Ruhe-servlet.xml konfigurierte:

<bean id="jackson2Converter" class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"> 
     <property name="objectMapper" ref="jackson2ObjectMapper" /> 
     <property name="supportedMediaTypes" value="application/json" /> 
    </bean> 

aus meiner Controller-Klasse Ich bin über ein Response-Objekt zurück unter anderem enthält, auf das Client eine javax.activation.Datahandler zurück.

Dieser Datahandler enthält eine Base64-Darstellung einer binären PDF-Datei. Wenn ich dieses Datahandler-Feld manuell auf Null setze, wird die Antwort erfolgreich an Json gemarshallt, und ich kann die Körperantwort in meinem Test-Tool, Postman, erfolgreich sehen.

Wenn ich nicht tun, das heißt, bring sie mit dem Datahandler Feld (mit Base64-Darstellung des pdf), mein Dienst schlägt mit dem folgenden Stack-Trace:

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2017-12-20 07:51:27,028 ERROR [RestResponseEntityExceptionHandler] cannot do this 
java.io.IOException: cannot do this 
    at javax.mail.util.ByteArrayDataSource.getOutputStream(ByteArrayDataSource.java:169) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:497) 
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:536) 
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:663) 
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:663) 
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:663) 
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:575) 
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:663) 
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:156) 
    at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:129) 
    at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:2238) 
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.writeInternal(MappingJackson2HttpMessageConverter.java:194) 
    at org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:179) 
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:148) 
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:90) 
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:189) 
    at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:69) 
    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: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:936) 
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:838) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648) 
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at no.gjensidige.earkiv.api.logging.LoggingFilter.doFilter(LoggingFilter.java:83) 
    at no.gjensidige.earkiv.api.logging.LoggingFilter.doFilter(LoggingFilter.java:72) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at no.gjensidige.security.spnego.SpnegoServletFilter.filterAsAnonymous(SpnegoServletFilter.java:138) 
    at no.gjensidige.security.spnego.SpnegoServletFilter.doFilter(SpnegoServletFilter.java:75) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at org.apache.catalina.filters.CorsFilter.handleNonCORS(CorsFilter.java:436) 
    at org.apache.catalina.filters.CorsFilter.doFilter(CorsFilter.java:177) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:201) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:614) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 
    at org.apache.catalina.valves.StuckThreadDetectionValve.invoke(StuckThreadDetectionValve.java:208) 
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 
    at java.lang.Thread.run(Thread.java:745) 

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Can jemand zeigt mir in welche richtung jackson converter zu verwenden um diese datahandler klasse richtig marshall?

Answer 1

Es ist nicht möglich. javax.activation.Datahandler hat Verweise auf Streams und Factories, die nicht serialisierbar sind.

Erstellen Sie stattdessen eine benutzerdefinierte POJO-Klasse - Data TransferObject, speichern Sie alle erforderlichen Informationen von javax.activation.Datahandler zum DTO-Objekt und übergeben Sie sie als Antwort.

In Ihrem Fall nicht die Instanz, sondern Base64 codierte Zeichenfolge stattdessen gesendet.