Apache Kafka和Avro:org.Apache.Avro.generic.GenericData$Record不能强制转换为com.harmeetsingh13.java.Customer
每当我试图从kafka队列读取消息时,我都会遇到以下异常:Apache Kafka和Avro:org.Apache.Avro.generic.GenericData$Record不能强制转换为com.harmeetsingh13.java.Customer,java,apache-kafka,avro,kafka-consumer-api,kafka-producer-api,Java,Apache Kafka,Avro,Kafka Consumer Api,Kafka Producer Api,每当我试图从kafka队列读取消息时,我都会遇到以下异常: [error] (run-main-0) java.lang.ClassCastException: org.apache.avro.generic.GenericData$Record cannot be cast to com.harmeetsingh13.java.Customer java.lang.ClassCastException: org.apache.avro.generic.GenericData$Record ca
[error] (run-main-0) java.lang.ClassCastException: org.apache.avro.generic.GenericData$Record cannot be cast to com.harmeetsingh13.java.Customer
java.lang.ClassCastException: org.apache.avro.generic.GenericData$Record cannot be cast to com.harmeetsingh13.java.Customer
at com.harmeetsingh13.java.consumers.avrodesrializer.AvroSpecificDeserializer.infiniteConsumer(AvroSpecificDeserializer.java:79)
at com.harmeetsingh13.java.consumers.avrodesrializer.AvroSpecificDeserializer.main(AvroSpecificDeserializer.java:87)
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:498)
卡夫卡制作人代码:
public class AvroSpecificProducer {
private static Properties kafkaProps = new Properties();
private static KafkaProducer<String, Customer> kafkaProducer;
static {
kafkaProps.put("bootstrap.servers", "localhost:9092");
kafkaProps.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, KafkaAvroSerializer.class);
kafkaProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, KafkaAvroSerializer.class);
kafkaProps.put("schema.registry.url", "http://localhost:8081");
kafkaProducer = new KafkaProducer<>(kafkaProps);
}
public static void fireAndForget(ProducerRecord<String, Customer> record) {
kafkaProducer.send(record);
}
public static void asyncSend(ProducerRecord<String, Customer> record) {
kafkaProducer.send(record, (recordMetaData, ex) -> {
System.out.println("Offset: "+ recordMetaData.offset());
System.out.println("Topic: "+ recordMetaData.topic());
System.out.println("Partition: "+ recordMetaData.partition());
System.out.println("Timestamp: "+ recordMetaData.timestamp());
});
}
public static void main(String[] args) throws InterruptedException, IOException {
Customer customer1 = new Customer(1002, "Jimmy");
ProducerRecord<String, Customer> record1 = new ProducerRecord<>("CustomerSpecificCountry",
"Customer One 11 ", customer1
);
asyncSend(record1);
Thread.sleep(1000);
}
}
公共类AvroSpecificProducer{
私有静态属性kafkapprops=新属性();
私人静态卡夫卡制作人卡夫卡制作人;
静止的{
kafkaProps.put(“bootstrap.servers”,“localhost:9092”);
kafkaaprops.put(ProducerConfig.KEY\u SERIALIZER\u CLASS\u CONFIG,KafkaAvroSerializer.CLASS);
kafkaaprops.put(ProducerConfig.VALUE\u SERIALIZER\u CLASS\u CONFIG,KafkaAvroSerializer.CLASS);
kafkaProps.put(“schema.registry.url”)http://localhost:8081");
卡夫卡普洛斯=新卡夫卡普洛斯(卡夫卡普洛斯);
}
公共静态无效fireAndForget(生产记录记录){
kafkaProducer.send(记录);
}
公共静态无效异步发送(生产记录记录){
kafkaProducer.send(记录,(记录元数据,ex)->{
System.out.println(“Offset:+recordMetaData.Offset());
System.out.println(“主题:+recordMetaData.Topic());
System.out.println(“分区:+recordMetaData.Partition());
System.out.println(“Timestamp:+recordMetaData.Timestamp());
});
}
公共静态void main(字符串[]args)引发InterruptedException、IOException{
客户customer1=新客户(1002,“吉米”);
ProducerRecord1=新的ProducerRecord(“CustomerSpecificCountry”,
“客户一号11”,客户一号
);
异步发送(记录1);
睡眠(1000);
}
}
卡夫卡消费代码:
public class AvroSpecificDeserializer {
private static Properties kafkaProps = new Properties();
static {
kafkaProps.put(ConsumerConfig.GROUP_ID_CONFIG, "CustomerCountryGroup1");
kafkaProps.put("zookeeper.connect", "localhost:2181");
kafkaProps.put("schema.registry.url", "http://localhost:8081");
}
public static void infiniteConsumer() throws IOException {
VerifiableProperties properties = new VerifiableProperties(kafkaProps);
KafkaAvroDecoder keyDecoder = new KafkaAvroDecoder(properties);
KafkaAvroDecoder valueDecoder = new KafkaAvroDecoder(properties);
Map<String, Integer> topicCountMap = new HashMap<>();
topicCountMap.put("NewTopic", 1);
ConsumerConnector consumer = createJavaConsumerConnector(new kafka.consumer.ConsumerConfig(kafkaProps));
Map<String, List<KafkaStream<Object, Object>>> consumerMap = consumer.createMessageStreams(topicCountMap, keyDecoder, valueDecoder);
KafkaStream stream = consumerMap.get("NewTopic").get(0);
ConsumerIterator it = stream.iterator();
System.out.println("???????????????????????????????????????????????? ");
while (it.hasNext()) {
System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> ");
MessageAndMetadata messageAndMetadata = it.next();
String key = (String) messageAndMetadata.key();
GenericRecord record = (GenericRecord) messageAndMetadata.message();
Customer customer = (Customer) SpecificData.get().deepCopy(Customer.SCHEMA$, record);
System.out.println("Key: " + key);
System.out.println("Value: " + customer);
}
}
public static void main(String[] args) throws IOException {
infiniteConsumer();
}
}
公共类AvroSpecificDeserializer{
私有静态属性kafkapprops=新属性();
静止的{
kafkaProps.put(ConsumerConfig.GROUP_ID_CONFIG,“CustomerCountryGroup1”);
kafkaProps.put(“zookeeper.connect”,“localhost:2181”);
kafkaProps.put(“schema.registry.url”)http://localhost:8081");
}
公共静态void infiniteConsumer()引发IOException{
可验证属性=新的可验证属性(Kafkapprops);
KafkaAvroDecoder keyDecoder=新的KafkaAvroDecoder(属性);
KafkaAvroDecoder valueDecoder=新的KafkaAvroDecoder(属性);
Map topicCountMap=新HashMap();
topicCountMap.put(“NewTopic”,1);
ConsumerConnector consumer=createJavaConsumerConnector(新的kafka.consumer.ConsumerConfig(kafkaProps));
Map consumerMap=consumer.createMessageStreams(topicCountMap、keyDecoder、valueDecoder);
KafkaStream stream=consumerMap.get(“NewTopic”).get(0);
ConsumerIterator it=stream.iterator();
System.out.println(“????????????????????????????”;
while(it.hasNext()){
系统输出打印项次(“>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>”;
MessageAndMetadata MessageAndMetadata=it.next();
String key=(String)messageAndMetadata.key();
GenericRecord=(GenericRecord)messageAndMetadata.message();
Customer=(Customer)SpecificData.get().deepCopy(Customer.SCHEMA$,record);
System.out.println(“Key:+Key”);
System.out.println(“值:+customer”);
}
}
公共静态void main(字符串[]args)引发IOException{
无限消费者();
}
}
以下是我举的例子:
在与@harmeen讨论之后,这是最终可行的代码
static {
kafkaProps.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "smallest");
kafkaProps.put(ConsumerConfig.GROUP_ID_CONFIG, "CustomerCountryGroup1");
kafkaProps.put("zookeeper.connect", "localhost:2181");
kafkaProps.put("schema.registry.url", "http://localhost:8081");
kafkaProps.put(KafkaAvroDeserializerConfig.SPECIFIC_AVRO_READER_CONFIG, true);
}
public static void infiniteConsumer() throws IOException {
VerifiableProperties properties = new VerifiableProperties(kafkaProps);
StringDecoder keyDecoder = new StringDecoder(properties);
KafkaAvroDecoder valueDecoder = new KafkaAvroDecoder(properties);
Map<String, Integer> topicCountMap = new HashMap<>();
topicCountMap.put("BrandNewTopics", 1);
ConsumerConnector consumer = createJavaConsumerConnector(new kafka.consumer.ConsumerConfig(kafkaProps));
Map<String, List<KafkaStream<String, Object>>> consumerMap = consumer.createMessageStreams(topicCountMap, keyDecoder, valueDecoder);
KafkaStream stream = consumerMap.get("BrandNewTopics").get(0);
ConsumerIterator it = stream.iterator();
while (it.hasNext()) {
MessageAndMetadata messageAndMetadata = it.next();
String key = (String) messageAndMetadata.key();
GenericRecord record = (GenericRecord) messageAndMetadata.message();
Customer customer = (Customer) SpecificData.get().deepCopy(Customer.SCHEMA$, record);
System.out.println("Key: " + key);
System.out.println("Value: " + customer);
}
static{
kafkaProps.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG,“最小”);
kafkaProps.put(ConsumerConfig.GROUP_ID_CONFIG,“CustomerCountryGroup1”);
kafkaProps.put(“zookeeper.connect”,“localhost:2181”);
kafkaProps.put(“schema.registry.url”)http://localhost:8081");
kafkavrodeserializerconfig.SPECIFIC_AVRO_READER_CONFIG,true);
}
公共静态void infiniteConsumer()引发IOException{
可验证属性=新的可验证属性(Kafkapprops);
StringDecoder keyDecoder=新的StringDecoder(属性);
KafkaAvroDecoder valueDecoder=新的KafkaAvroDecoder(属性);
Map topicCountMap=新HashMap();
topicCountMap.put(“BrandNewTopics”,1);
ConsumerConnector consumer=createJavaConsumerConnector(新的kafka.consumer.ConsumerConfig(kafkaProps));
Map consumerMap=consumer.createMessageStreams(topicCountMap、keyDecoder、valueDecoder);
KafkaStream stream=consumerMap.get(“BrandNewTopics”).get(0);
ConsumerIterator it=stream.iterator();
而(it.hasNext()){
MessageAndMetadata MessageAndMetadata=it.next();
String key=(String)messageAndMetadata.key();
GenericRecord=(GenericRecord)messageAndMetadata.message();
Customer=(Customer)SpecificData.get().deepCopy(Customer.SCHEMA$,record);
System.out.println(“Key:+Key”);
System.out.println(“值:+customer”);
}
发生变化的事情:
- 将
属性添加为trueSPECIFIC\u AVRO\u READER\u CONFIG
- 使用最小值从主题的开头开始
- 对键使用
和StringSerializer
StringDeserializer
- 更改生产者和消费者以反映以前的更改
- 调整代表Avro记录的
类的名称空间Customer