我试图在一个非常简单的项目中使用Spring Kafak，但在收到String消息时出错。Spring Boot版本为2.2.6.RELEASE。这是我的应用程序的内容。yml(根据官方的Spring Boot文档，应该足够了(：
spring:
kafka:
consumer:
group-id: group-id
auto-offset-reset: earliest
这是侦听器类：
@Service
@Slf4j
@KafkaListener(topics = KafkaSampleApplication.TOPIC)
public class MessageReceiver {
public void consume(ConsumerRecord<?, ?> cr) throws Exception {
log.info(String.format("$$ -> Consumed Message -> %s", cr.toString()));
}
}
这就是错误：
2020-04-11 11:21:04.265 INFO 11032 --- [ntainer#0-0-C-1] o.s.k.l.KafkaMessageListenerContainer : group-id: partitions assigned: [claudiotopic01-0]
2020-04-11 11:21:04.296 ERROR 11032 --- [ntainer#0-0-C-1] o.s.kafka.listener.LoggingErrorHandler : Error while processing: ConsumerRecord(topic = claudiotopic01, partition = 0, leaderEpoch = 0, offset = 3, CreateTime = 1586595579264, serialized key size = -1, serialized value size = 5, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = ciao4)
org.springframework.kafka.listener.ListenerExecutionFailedException: Listener failed; nested exception is org.springframework.kafka.KafkaException: No method found for class java.lang.String
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.decorateException(KafkaMessageListenerContainer.java:1790) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.invokeErrorHandler(KafkaMessageListenerContainer.java:1779) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.doInvokeRecordListener(KafkaMessageListenerContainer.java:1692) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.doInvokeWithRecords(KafkaMessageListenerContainer.java:1618) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.invokeRecordListener(KafkaMessageListenerContainer.java:1521) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.invokeListener(KafkaMessageListenerContainer.java:1262) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.pollAndInvoke(KafkaMessageListenerContainer.java:1009) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.run(KafkaMessageListenerContainer.java:929) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [na:1.8.0_171]
at java.util.concurrent.FutureTask.run(Unknown Source) [na:1.8.0_171]
at java.lang.Thread.run(Unknown Source) [na:1.8.0_171]
Caused by: org.springframework.kafka.KafkaException: No method found for class java.lang.String
at org.springframework.kafka.listener.adapter.DelegatingInvocableHandler.getHandlerForPayload(DelegatingInvocableHandler.java:170) ~[spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.adapter.DelegatingInvocableHandler.getMethodNameFor(DelegatingInvocableHandler.java:279) ~[spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.adapter.HandlerAdapter.getMethodAsString(HandlerAdapter.java:67) ~[spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:346) ~[spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.adapter.RecordMessagingMessageListenerAdapter.onMessage(RecordMessagingMessageListenerAdapter.java:86) ~[spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.adapter.RecordMessagingMessageListenerAdapter.onMessage(RecordMessagingMessageListenerAdapter.java:51) ~[spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.doInvokeOnMessage(KafkaMessageListenerContainer.java:1741) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.invokeOnMessage(KafkaMessageListenerContainer.java:1724) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.doInvokeRecordListener(KafkaMessageListenerContainer.java:1679) [spring-kafka-2.3.7.RELEASE.jar:2.3.7.RELEASE]
... 8 common frames omitted
这是启动时消费者配置的输出：
020-04-11 11:21:04.218[0;39m [32m INFO[0;39m [35m11032[0;39m [2m---[0;39m [2m[ restartedMain][0;39m [36mo.a.k.clients.consumer.ConsumerConfig [0;39m [2m:[0;39m ConsumerConfig values:
allow.auto.create.topics = true
auto.commit.interval.ms = 5000
auto.offset.reset = earliest
bootstrap.servers = [localhost:9092]
check.crcs = true
client.dns.lookup = default
client.id =
client.rack =
connections.max.idle.ms = 540000
default.api.timeout.ms = 60000
enable.auto.commit = false
exclude.internal.topics = true
fetch.max.bytes = 52428800
fetch.max.wait.ms = 500
fetch.min.bytes = 1
group.id = group-id
group.instance.id = null
heartbeat.interval.ms = 3000
interceptor.classes = []
internal.leave.group.on.close = true
isolation.level = read_uncommitted
key.deserializer = class org.apache.kafka.common.serialization.StringDeserializer
max.partition.fetch.bytes = 1048576
max.poll.interval.ms = 300000
max.poll.records = 500
metadata.max.age.ms = 300000
metric.reporters = []
metrics.num.samples = 2
metrics.recording.level = INFO
metrics.sample.window.ms = 30000
partition.assignment.strategy = [class org.apache.kafka.clients.consumer.RangeAssignor]
receive.buffer.bytes = 65536
reconnect.backoff.max.ms = 1000
reconnect.backoff.ms = 50
request.timeout.ms = 30000
retry.backoff.ms = 100
sasl.client.callback.handler.class = null
sasl.jaas.config = null
sasl.kerberos.kinit.cmd = /usr/bin/kinit
sasl.kerberos.min.time.before.relogin = 60000
sasl.kerberos.service.name = null
sasl.kerberos.ticket.renew.jitter = 0.05
sasl.kerberos.ticket.renew.window.factor = 0.8
sasl.login.callback.handler.class = null
sasl.login.class = null
sasl.login.refresh.buffer.seconds = 300
sasl.login.refresh.min.period.seconds = 60
sasl.login.refresh.window.factor = 0.8
sasl.login.refresh.window.jitter = 0.05
sasl.mechanism = GSSAPI
security.protocol = PLAINTEXT
send.buffer.bytes = 131072
session.timeout.ms = 10000
ssl.cipher.suites = null
ssl.enabled.protocols = [TLSv1.2, TLSv1.1, TLSv1]
ssl.endpoint.identification.algorithm = https
ssl.key.password = null
ssl.keymanager.algorithm = SunX509
ssl.keystore.location = null
ssl.keystore.password = null
ssl.keystore.type = JKS
ssl.protocol = TLS
ssl.provider = null
ssl.secure.random.implementation = null
ssl.trustmanager.algorithm = PKIX
ssl.truststore.location = null
ssl.truststore.password = null
ssl.truststore.type = JKS
value.deserializer = class org.apache.kafka.common.serialization.StringDeserializer
@KafkaListener在方法上，而不是在类上，除非您想使用多方法侦听器，在这种情况下，方法上需要@KafkaHandler。