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java - 尝试运行简单的 Kafka Stream App 时收到异常

问题描述

我一直在尝试使用 Kafka 运行一个简单的 wordcount 应用程序，但是每当我运行它时，都会出现以下错误：

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/kafka/common/utils/LogContext
    at org.apache.kafka.streams.KafkaStreams.<init>(KafkaStreams.java:630)
    at org.apache.kafka.streams.KafkaStreams.<init>(KafkaStreams.java:610)
    at org.apache.kafka.streams.KafkaStreams.<init>(KafkaStreams.java:557)
    at StreamsApp.main(StreamsApp.java:49)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at com.intellij.rt.execution.application.AppMainV2.main(AppMainV2.java:131)
Caused by: java.lang.ClassNotFoundException: org.apache.kafka.common.utils.LogContext
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)

我不知道为什么我不断收到这个错误......下面列出了主要方法的代码。（第 49 行）KafkaStreams 流 = new KafkaStreams(topology, props);

public static void main(final String[] args) throws Exception {

    Properties props = new Properties();
    props.put(StreamsConfig.APPLICATION_ID_CONFIG, "wordcount-application");
    props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
    props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
    props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
    props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
    // props.put(StreamsConfig.STATE_DIR_CONFIG, TestUtils.tempDirectory().getAbsolutePath());

    StreamsBuilder builder = new StreamsBuilder();
    KStream<String, String> textLines = builder.stream("inputTopic");
    final Pattern pattern = Pattern.compile("\\W+", Pattern.UNICODE_CHARACTER_CLASS);

    KTable<String, Long> wordCounts = textLines
            .flatMapValues(value -> Arrays.asList(pattern.split(value.toLowerCase())))
            .groupBy((key, word) -> word)
            .count();

    wordCounts
            .foreach((w, c) -> System.out.println("word: " + w + " -> " + c));


    String outputTopic = "outputTopic";
    Serde<String> stringSerde = Serdes.String();
    Serde<Long> longSerde = Serdes.Long();
    wordCounts.to(stringSerde, longSerde, outputTopic);

    Topology topology = builder.build();

    KafkaStreams streams = new KafkaStreams(topology, props);
    streams.start();

    Thread.sleep(30000);
    streams.close();

}

}

标签： javaapache-kafkaapache-kafka-streams

解决方案

您在依赖项org.apache.kafka:kafka-streams和org.apache.kafka:kafka-clients. 根据您的例外，您使用的kafka-clients版本小于 1.0.0，但kafka-streams版本等于或高于 1.0.0。

确保该kafka-clients版本至少为 1.0.0（因此您需要升级您的kafka-clients版本），否则您需要降级kafka-streams版本。

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