pom.xml
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka-clients</artifactId>
            <version>2.3.1</version>
        </dependency>

注意调试通过后要添加log-back.xml并设置日志级别到info及以上，否则debug日志实在是多啊……

///ProducerTest.java

package com.whq.demo;
import java.util.Properties;
import java.util.Random;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.serialization.StringSerializer;
public class ProducerTest {public static String topic = "whq_test";//定义主题public static void main(String[] args) throws InterruptedException {Properties p = new Properties();p.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.81.145:9092,192.168.81.145:9093,192.168.81.145:9094");//kafka地址，多个地址用逗号分割p.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);p.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);KafkaProducer<String, String> kafkaProducer = new KafkaProducer<>(p);try {while (true) {String msg = "Hello,你好," + new Random().nextInt(100);ProducerRecord<String, String> record = new ProducerRecord<String, String>(topic, msg);kafkaProducer.send(record);System.out.println("消息发送成功:" + msg);Thread.sleep(500);}} finally {kafkaProducer.close();}}
}

///ConsumerTest.java

package com.whq.demo;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.serialization.StringDeserializer;import java.util.Collections;
import java.util.Properties;public class ConsumerTest {public static void main(String[] args) {Properties p = new Properties();p.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.81.145:9092,192.168.81.145:9093,192.168.81.145:9094");p.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);p.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);p.put(ConsumerConfig.GROUP_ID_CONFIG, "3");//组编号，不同的组提交偏移不同p.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG,true);//自动提交，提交后数据在同组无法再次获取,否则同组另外消费者接入还会收到同样的消息p.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG,"earliest");/*** AUTO_OFFSET_RESET_CONFIG 重置偏移设置* earliest* 当各分区下有已提交的offset时，从提交的offset开始消费；无提交的offset时，从头开始消费* latest* 当各分区下有已提交的offset时，从提交的offset开始消费；无提交的offset时，消费新产生的该分区下的数据* none* topic各分区都存在已提交的offset时，从offset后开始消费；只要有一个分区不存在已提交的offset，则抛出异常*/KafkaConsumer<String, String> kafkaConsumer = new KafkaConsumer<String, String>(p);kafkaConsumer.subscribe(Collections.singletonList(ProducerTest.topic));// 订阅消息while (true) {ConsumerRecords<String, String> records = kafkaConsumer.poll(100);for (ConsumerRecord<String, String> record : records) {System.out.println(String.format("topic:%s,offset:%d,消息:%s", //record.topic(), record.offset(), record.value()));}}}
}

//出现问题：生产者第二次发消息时连接到了127.0.0.1:9093，后来发现是kafka服务器配置问题：
vi config/server.properties
修改

listeners=PLAINTEXT://192.168.81.145:9092    #注意，这里一定要有客户端可访问的ip，否则非本机连接调用第二次会异常