java - Kafka 生产者异常 NoClassDefFoundError

Question

kafka Producer 有一些问题，但我不知道如何解决

我的 Maven 依赖项:

  <dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka_2.10</artifactId>
    <version>0.10.1.1</version>
</dependency>

如果我创建:

 Producer<String, byte[]> producer = createKafkaProducer();

我成为异常(exception):

java.lang.NoClassDefFoundError: org/apache/kafka/clients/producer/Producer
at de.dienes.opitz.node.NodesValue.onSubscriptionValue(NodesValue.java:120)
at org.eclipse.milo.opcua.sdk.client.subscriptions.OpcUaMonitoredItem.onValueArrived(OpcUaMonitoredItem.java:176)
at org.eclipse.milo.opcua.sdk.client.subscriptions.OpcUaSubscriptionManager.lambda$null$28(OpcUaSubscriptionManager.java:547)
at org.eclipse.milo.opcua.stack.core.util.ExecutionQueue$PollAndExecute.run(ExecutionQueue.java:107)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: org.apache.kafka.clients.producer.Producer
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 9 common frames omitted

问题出在哪里？

Answer 1

org.apache.kafka.clients.producer.Producer 位于 kafka-clients Artifact 中。你应该使用

<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka-clients</artifactId>
    <version>0.10.2.1</version>
</dependency>

kafka_2.10 是代理的 Artifact 。如果您只是编写生产者/消费者，则不需要它(除了针对测试集群对生产者/消费者进行集成测试)。