A simple Kafka consumer implemented in Java:
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import java.time.Duration;
import java.util.Arrays;
import java.util.Properties;
public class Consumer {
private final static String KAFKA_URL = "localhost:9092"; //Kafka的IP地址
private final static String TOPIC = "test"; //需要订阅的Topic
private final static String GROUP_ID = "123"; //group id可以随便取
public static void main(String[] args) {
try {
Properties properties = new Properties();
properties.put("bootstrap.servers", KAFKA_URL);
properties.put("group.id", GROUP_ID);
properties.put("enable.auto.commit", "true");
properties.put("auto.commit.interval.ms", "1000");
properties.put("auto.offset.reset", "earliest"); //从队列的最早消息开始订阅
properties.put("session.timeout.ms", "30000");
properties.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
properties.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
KafkaConsumer<String, String> kafkaConsumer = new KafkaConsumer<>(properties);
kafkaConsumer.subscribe(Arrays.asList(TOPIC));
while (true) {
ConsumerRecords<String, String> records = kafkaConsumer.poll(Duration.ofMillis(0));
for (ConsumerRecord<String, String> record : records) {
System.out.printf("offset = %d, value = %s", record.offset(), record.value()); //输出订阅到的消息
System.out.println();
}
}
}
catch (Exception ex) {
ex.printStackTrace();
System.out.println("when calling kafka output error." + ex.getMessage());
}
}
}