用java写spark消费kafka的消息
时间: 2023-07-04 12:17:46 浏览: 74
当使用Java编写Spark消费Kafka消息时,你需要使用Kafka的Java API和Spark的Java API来编写代码。
首先,你需要引入Kafka和Spark的Java API依赖项。例如,如果你使用Maven,可以在pom.xml文件中添加以下依赖项:
```xml
<dependency>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka-clients</artifactId>
<version>2.8.0</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.11</artifactId>
<version>2.4.4</version>
</dependency>
```
然后,你需要编写Java代码来创建Spark Streaming应用程序,并从Kafka主题中读取消息。以下是一个示例代码:
```java
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.api.java.function.Function;
import org.apache.spark.streaming.Duration;
import org.apache.spark.streaming.api.java.JavaDStream;
import org.apache.spark.streaming.api.java.JavaInputDStream;
import org.apache.spark.streaming.api.java.JavaStreamingContext;
import org.apache.spark.streaming.kafka010.ConsumerStrategies;
import org.apache.spark.streaming.kafka010.KafkaUtils;
import org.apache.spark.streaming.kafka010.LocationStrategies;
public class ConsumeKafkaMessages {
public static void main(String[] args) {
String brokers = "localhost:9092";
String groupId = "test-group";
String topics = "test-topic";
SparkConf conf = new SparkConf().setAppName("ConsumeKafkaMessages");
JavaStreamingContext jssc = new JavaStreamingContext(conf, new Duration(1000));
Map<String, Object> kafkaParams = new HashMap<>();
kafkaParams.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, brokers);
kafkaParams.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
kafkaParams.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
kafkaParams.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
JavaInputDStream<ConsumerRecord<String, String>> stream =
KafkaUtils.createDirectStream(
jssc,
LocationStrategies.PreferConsistent(),
ConsumerStrategies.<String, String>Subscribe(Arrays.asList(topics), kafkaParams)
);
JavaDStream<String> messages = stream.map(
new Function<ConsumerRecord<String, String>, String>() {
@Override
public String call(ConsumerRecord<String, String> record) throws Exception {
return record.value();
}
}
);
// 对消息进行处理
// ...
jssc.start();
jssc.awaitTermination();
}
}
```
以上代码将从名为"test-topic"的Kafka主题中读取消息,并将它们转换为String类型的数据流。你需要根据需要在代码中添加适当的数据处理逻辑。
你可以根据你的需要修改代码来适应不同的数据集格式和处理方式。
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