尝试在Kafka中创建分区时出现NoClassDefFoundError

Question

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consumer.partitionsFor(主题(被执行时，我得到以下错误：

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)

引起原因：java.lang.ClassNotFoundException：com.fasterxml.jackson.databind.JsonNode位于java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581(位于java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178(位于java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522(…还有68个

在pom.xml中，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>

我所能找到的建议就是添加jackson注释和-core到maven依赖关系，但这并没有帮助。

Answer 1

这是2.6版本客户端中的一个错误：https://issues.apache.org/jira/browse/KAFKA-10378

我建议在2.6.1或2.7发布之前坚持使用2.5客户端。除非有一个关键的2.6功能是你离不开的，否则建议你加入自己的依赖性是合理的。

Answer 2

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>

然而，您应该真正使用jackson-bom来一致地导入所有相关的依赖版本