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java - 尝试在 Kafka 中创建分区时出现 NoClassDefFoundError

问题描述

我有以下代码：

  public KafkaReader(KafkaConsumer<Long, byte[]> consumer, String topic) {
    this.consumer = consumer;
    this.topicPartition = new TopicPartition(topic, ((consumer.partitionsFor(topic).get(0)).partition()));
    consumer.assign(Collections.singleton(topicPartition));
}

但是当执行 consumer.partitionsFor(topic) 时，我收到以下错误：

java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/JsonNode

at org.apache.kafka.common.requests.MetadataRequest$Builder.<clinit>(MetadataRequest.java:36)
at org.apache.kafka.clients.consumer.KafkaConsumer.partitionsFor(KafkaConsumer.java:1962)
at org.apache.kafka.clients.consumer.KafkaConsumer.partitionsFor(KafkaConsumer.java:1930)
at data.KafkaReader.<init>(KafkaReader.java:20)
at data.KafkaReaderTest.playground(KafkaReaderTest.java:12)

...引起：java.lang.ClassNotFoundException：com.fasterxml.jackson.databind.JsonNode at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581) at java.base/jdk.internal .loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) 在 java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522) ... 68 更多

在 pom.xml 我定义了以下依赖项：

   <dependencies>
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter-engine</artifactId>
        <version>${junit.jupiter.version}</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.hamcrest</groupId>
        <artifactId>hamcrest-all</artifactId>
        <version>1.3</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>commons-cli</groupId>
        <artifactId>commons-cli</artifactId>
        <version>1.4</version>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.12</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.kafka</groupId>
        <artifactId>kafka-clients</artifactId>
        <version>2.6.0</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.25</version>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.8.10</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.8.10</version>
    </dependency>
</dependencies>

我发现的所有建议都是将 jackson-annotations 和 -core 添加到 maven 依赖项，但这没有帮助。

标签： javaapache-kafkajacksonfasterxml

解决方案

ClassNotFoundException：com.fasterxml。jackson.databind .JsonNode

所以你需要

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.8.10</version>
</dependency>

但是，您真的应该使用jackson-bom一致地导入所有相关的依赖版本

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