我正在编写一个应用程序，该应用程序处理传入的坐标记录并监视它们在定义的地理围栏中的进入或退出。中间，我正在使用聚合来保持当前坐标是在特定地理围栏之内还是之外。
以下是运行此错误时的错误堆栈跟踪：
Exception in thread "geofence-events-990be707-d44d-410d-a8a7-b2a3b90cb84f-StreamThread-1" org.apache.kafka.streams.errors.StreamsException: Exception caught in process. taskId=0_0, processor=KSTREAM-SOURCE-0000000003, topic=vehicle-sensor-data, partition=0, offset=0
at org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:367)
at org.apache.kafka.streams.processor.internals.AssignedStreamsTasks.process(AssignedStreamsTasks.java:104)
at org.apache.kafka.streams.processor.internals.TaskManager.process(TaskManager.java:413)
at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:862)
at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:777)
at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:747)
Caused by: org.apache.kafka.streams.errors.StreamsException: A serializer (key: org.apache.kafka.common.serialization.StringSerializer / value: org.apache.kafka.common.serialization.StringSerializer) is not compatible to the actual key or value type (key type: java.lang.String / value type: com.loconav.GeoFenceDTO). Change the default Serdes in StreamConfig or provide correct Serdes via method parameters.
at org.apache.kafka.streams.processor.internals.SinkNode.process(SinkNode.java:94)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:146)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:129)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:93)
at org.apache.kafka.streams.kstream.internals.KStreamFilter$KStreamFilterProcessor.process(KStreamFilter.java:43)
at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:115)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:146)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:129)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:93)
at org.apache.kafka.streams.kstream.internals.KStreamMap$KStreamMapProcessor.process(KStreamMap.java:42)
at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:115)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:146)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:129)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:93)
at org.apache.kafka.streams.kstream.internals.KStreamPeek$KStreamPeekProcessor.process(KStreamPeek.java:44)
at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:115)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:146)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:129)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:93)
at org.apache.kafka.streams.kstream.internals.KStreamFlatMapValues$KStreamFlatMapValuesProcessor.process(KStreamFlatMapValues.java:42)
at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:115)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:146)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:129)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:93)
at org.apache.kafka.streams.kstream.internals.KStreamKTableJoinProcessor.process(KStreamKTableJoinProcessor.java:73)
at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:115)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:146)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:129)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:93)
at org.apache.kafka.streams.kstream.internals.KStreamFlatMapValues$KStreamFlatMapValuesProcessor.process(KStreamFlatMapValues.java:42)
at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:115)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:146)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:129)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:93)
at org.apache.kafka.streams.kstream.internals.KStreamMap$KStreamMapProcessor.process(KStreamMap.java:42)
at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:115)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:146)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:129)
at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:93)
at org.apache.kafka.streams.processor.internals.SourceNode.process(SourceNode.java:84)
at org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:351)
... 5 more
Caused by: java.lang.ClassCastException: class com.loconav.GeoFenceDTO cannot be cast to class java.lang.String (com.loconav.GeoFenceDTO is in unnamed module of loader 'app'; java.lang.String is in module java.base of loader 'bootstrap')
at org.apache.kafka.common.serialization.StringSerializer.serialize(StringSerializer.java:28)
at org.apache.kafka.common.serialization.Serializer.serialize(Serializer.java:60)
at org.apache.kafka.streams.processor.internals.RecordCollectorImpl.send(RecordCollectorImpl.java:157)
at org.apache.kafka.streams.processor.internals.RecordCollectorImpl.send(RecordCollectorImpl.java:101)
at org.apache.kafka.streams.processor.internals.SinkNode.process(SinkNode.java:89)
... 45 more
我在flatMapValues之后写了一个窥视，打印了第一条记录，然后发生此异常。下面是拓扑代码
vehicleGeoFences
.flatMapValues(
(readOnlyKey, value) -> {
List<GeoFenceDTO> geoFenceDTOS = new ArrayList<>();
// some logic
return geoFenceDTOS;
})
.groupBy((key, value) -> value.getGeofenceId() + "," + value.getVehicleId())
.aggregate(
GeoFenceDTO::new,
(key, value, aggregate) -> {
//setting values
return geofenceDTO;
},
Materialized.with(Serdes.String(), getGeofenceDTOValueSerde()))
.toStream()
.mapValues(
(readOnlyKey, value) -> {
// changing object
})
.to(
Topics.VEHICLE_EVENTS.name(),
Produced.with(vehicleEventsKeySerde, vehicleEventsValueSerde));
我在GeofenceDTO上编写了一个自定义Serde，而不是使用jackson ObjectMapper将对象转换为字节，反之亦然。某种程度上它看起来没有被实现。该应用程序的默认键值Serde为StringSerde。
帮助表示赞赏。 TIA。我尝试将自定义对象更改为Avro生成，但是仍然存在相同的错误。