spring - 使用 KafkaTemplate 发送返回使用 String 作为键的异常

Question

当使用整数作为键时，这不是问题，kafka 应该能够将字符串作为键来处理。

ProducerFactory<String, String> pf =
                new DefaultKafkaProducerFactory<String, String>(senderProps);
KafkaTemplate<String, String> template = new KafkaTemplate<>(pf);
ProducerRecord<String,String> pr = new ProducerRecord<>("my-topic", "key1","test");
        template.send(pr);`

它抛出以下异常:

Org.apache.kafka.common.errors.SerializationException: Can't convert key of class java.lang.String to class org.apache.kafka.common.serialization.IntegerSerializer specified in key.serializer

Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer at org.apache.kafka.common.serialization.IntegerSerializer.serialize(IntegerSerializer.java:21) at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:65) at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:55) at org.apache.kafka.clients.producer.KafkaProducer.doSend(KafkaProducer.java:799) at org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:784) at org.springframework.kafka.core.DefaultKafkaProducerFactory$CloseSafeProducer.send(DefaultKafkaProducerFactory.java:285) at org.springframework.kafka.core.KafkaTemplate.doSend(KafkaTemplate.java:357) at org.springframework.kafka.core.KafkaTemplate.send(KafkaTemplate.java:206)

Answer 1

看来，您的 Key 序列化程序在 ProducerConfig 中设置为 Integer。您需要将 KEY_SERIALIZER_CLASS_CONFIG 设置为 String :

@Bean
    public Map<String, Object> producerConfigs() {
        Map<String, Object> props = new HashMap<>();
        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        return props;
    }