springBoot连接kafka——JavaDemo

1.服务器配置kafka，进入kafka bin目录下，修改server.properties

vi config/server.properties

主要修改地方：

修改运行地址地址，改为虚拟机ip

# The address the socket server listens on. It will get the value returned from
# java.net.InetAddress.getCanonicalHostName() if not configured.
#   FORMAT:
#     listeners = listener_name://host_name:port
#   EXAMPLE:
#     listeners = PLAINTEXT://your.host.name:9092

# host.name=192.168.217.142 192.168.217.142为虚拟机服务ip，不修改java连接会报：
# java.net.ConnectException: Connection refused: no further information
listeners=PLAINTEXT://192.168.217.142:9092

修改kafka日志

log.dirs=/opt/kafka/kafka_2.12-2.5.0/logs
 

2.启动kafka

 bin/kafka-server-start.sh config/server.properties 

查看是否启动成功

 ps ef|grep kafka

查看进程

jps -l

3.查看防火墙是否开启，关闭防火墙（否则客户端无法访问）

firewall-cmd --state
如果是running的话

关闭防火墙(centos7关闭firewalld)

systemctl stop firewalld.service

Windows使用telnet测试端口能否访问

telnet 192.168.217.142 9092 如果可以进入界面就说明可以访问

4.java编写消息生产者

package com.qiming.kafka.chapter1;

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;

import java.util.Properties;

public class ProducerFastStart {
    // 主题名称-之前已经创建
    private static final String topic = "heima-per";
    // Kafka集群地址
    private static final String brokerList = "192.168.217.142:9092";

    public static void main(String[] args) {
        Properties properties = new Properties();
        // 设置key序列化器
        properties.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        //设置重试次数
        properties.put(ProducerConfig.RETRIES_CONFIG,10);

        // 设置值序列化器
        properties.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");

        //设置集群地址
        properties.put("bootstrap.servers", brokerList);

        KafkaProducer producer = new KafkaProducer(properties);
        ProducerRecord producerRecord = new ProducerRecord(topic,"kafka-demo","hello.kafka 23!!");

        try {
            producer.send(producerRecord);
        } catch (Exception e) {
            e.printStackTrace();
        }
        producer.close();
    }
}

5.java编写消息消费者

package com.qiming.kafka.chapter1;

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.Collections;
import java.util.Properties;

/**
 * Kafka 消息消费者
 */
public class ConsumerFastStart {
    // Kafka集群地址
    private static final String brokerList = "192.168.217.142:9092";
    // 主题名称-之前已经创建
    private static final String topic = "heima-per";
    // 消费组
    private static
    final String groupId = "group.demo";

    public static void main(String[] args) {
        Properties properties = new Properties();
        properties.put("key.deserializer",
                "org.apache.kafka.common.serialization.StringDeserializer");
        properties.put("value.deserializer",
                "org.apache.kafka.common.serialization.StringDeserializer");
        properties.put("bootstrap.servers", brokerList);
        properties.put("group.id", groupId);

        KafkaConsumer consumer = new KafkaConsumer<>(properties);
        consumer.subscribe(Collections.singletonList(topic));

        while (true) {
            ConsumerRecords records =
                    consumer.poll(Duration.ofMillis(1000));
            for (ConsumerRecord record : records) {
                System.out.println(record.value());
            }
        }
    }
}

6.启动消费者，不断监听，再启动消息生产者，可以看到消费者日志打出hello.kafka 23!!

 

注意：一定要先启动kafka