Question

我能够将我的java bean类作为avro记录发布到kafka。但是当我尝试消耗时，我得到了类强制转换异常。为什么会这样？

生产者

Schema schema = new Schema.Parser().parse(new File("/schemas/avro_schemas/test_schema.avsc"));

GenericRecord payload = new GenericData.Record(schema);
payload.put("name", fileName);
payload.put("timestamp", dateTime.toString());
payload.put("source", source);
payload.put("content", buf);
payload.put("customerCode", customercode); 
producer.publish(topic, payload, schema);

消费

ConsumerIterator<byte[], byte[]> it = stream.iterator();
while (it.hasNext()) {
try {
byte[] received_message = it.next().message();
Schema  schema = new Schema.Parser().parse(new File("/schemas/avro_schemas/test_schema.avsc"));
DatumReader<GenericRecord> reader = new SpecificDatumReader<GenericRecord>(schema);
Decoder decoder = DecoderFactory.get().binaryDecoder(received_message, null);
GenericRecord   payload = reader.read(null, decoder);

异常

ava.lang.ClassCastException: com.xxx.File cannot be cast to org.apache.avro.generic.IndexedRecord

at org.apache.avro.generic.GenericData.setField(GenericData.java:573)

at org.apache.avro.generic.GenericData.setField(GenericData.java:590)

at org.apache.avro.generic.GenericDatumReader.readField(GenericDatumReader.java:193)

at org.apache.avro.generic.GenericDatumReader.readRecord(GenericDatumReader.java:183)

at org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:151)

at org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:142)

at com.xxx.listener.KafkaMessageListenerThread.run(KafkaMessageListenerThread.java:56)

at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)

at java.util.

Avro架构

{
    "namespace": "com.xx"
     "type": "record",
     "name": "File",
     "fields":[
         {
            "name": "name", "type": "string"
         },
         {
            "name": "timestamp",  "type": "string"
         },
         {
            "name": "source", "type": "string"
         },
         {
            "name": "content", "type": "bytes"
         },
         {
            "name": "customerCode", "type": "string"
         }
     ]
}

Answer 1

基于评论者，问询者已经找到了解决方案：

我将更改后的SpecificDatumReader更改为GenericDatumReader

java.lang.ClassCastException：xx无法强制转换为org.apache.avro.generic.IndexedRecord

1 个答案: