kafka学习，kafka踩坑，使用java项目连接kafka发送消息报错连接超时问题

Posted 2022-03-22 干饭两斤半

背景：
在linux系统搭建好了kafka，使用java项目连接kafka发送消息，一直报错连接超时；再三检查，确实没有问题；很让人头疼；

解决
又认真的读了一下报错日志；
org.apache.kafka.common.errors.TimeoutException

org.apache.kafka.common.errors.TimeoutException: Expiring 1 record(s) for t2-0: 30042 ms has passed since batch creation plus linger time

于是开启Debug查看详细日志

java.io.IOException: Can't resolve address: izwz9c7asf4545sa85:9092
    at org.apache.kafka.common.network.Selector.connect(Selector.java:182) ~[kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.NetworkClient.initiateConnect(NetworkClient.java:629) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.NetworkClient.access$600(NetworkClient.java:57) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.NetworkClient$DefaultMetadataUpdater.maybeUpdate(NetworkClient.java:768) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.NetworkClient$DefaultMetadataUpdater.maybeUpdate(NetworkClient.java:684) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:347) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:226) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:203) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.awaitMetadataUpdate(ConsumerNetworkClient.java:138) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.consumer.internals.AbstractCoordinator.ensureCoordinatorReady(AbstractCoordinator.java:216) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.consumer.internals.AbstractCoordinator.ensureCoordinatorReady(AbstractCoordinator.java:193) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.consumer.internals.ConsumerCoordinator.poll(ConsumerCoordinator.java:275) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.consumer.KafkaConsumer.pollOnce(KafkaConsumer.java:1030) [kafka-clients-0.10.2.0.jar:na]
    at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:995) [kafka-clients-0.10.2.0.jar:na]
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.run(KafkaMessageListenerContainer.java:558) [spring-kafka-1.2.2.RELEASE.jar:na]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_144]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_144]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_144]
Caused by: java.nio.channels.UnresolvedAddressException: null
    at sun.nio.ch.Net.checkAddress(Net.java:101) ~[na:1.8.0_144]
    at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:622) ~[na:1.8.0_144]
    at org.apache.kafka.common.network.Selector.connect(Selector.java:179) ~[kafka-clients-0.10.2.0.jar:na]
    ... 17 common frames omitted

发现解析不了izwz9c7asf4545sa85:9092；
仔细观察发现izwz9c7asf4545sa85是阿里云服务器的host名。

于是在本地配置下hosts文件，加上izwz9c7asf4545sa85的host映射ip。

成功解决问题