Kafka 生产者消费者模式 写入/读取数据 [ 命令行/Java 代码 ]

 

一.确认配置文件：

打开config/server.properties 文件，修改broker.id，listeners，port,log.dirs

vi config/server.properties 

broker.id=0
listeners=PLAINTEXT://192.168.105.110:9092
port=9092
log.dirs=kafka-logs
zookeeper.connect=192.168.105.110:2181

备注：

listeners一定要配置成为IP地址；

如果配置为localhost或服务器的hostname,在使用java获取数据时会拿不到数据,或者发送数据时就会抛出异 常：org.apache.kafka.common.errors.TimeoutException: Batch Expired 。

因为在没有配置advertised.host.name 的情况下，Kafka并没有像官方文档宣称的那样改为广播我们配置的host.name，而是广播了主机配置的hostname。远端的客户端并没有配置 hosts，所以自然是连接不上这个hostname的
 

 

二.命令行创建生产者消费者

1.创建主题:

bin/kafka-topics.sh --create --zookeeper 192.168.105.110:2181 --replication-factor 1   --partitions 1 --topic Hello-Kafka

2.查看主题列表

bin/kafka-topics.sh --list --zookeeper 192.168.105.110:2181

3. 启动生产者以发送消息

 

bin/kafka-console-producer.sh --broker-list 192.168.105.110: 9092 --topic Hello-Kafka

 

4. 启动消费者,消费数据 (两种方式均可)

bin/kafka-console-consumer.sh --zookeeper 192.168.105.110:2181 --topic Hello-Kafka --from-beginning

bin/kafka-console-consumer.sh --bootstrap-server 192.168.105.110:9092  --topic  Hello-Kafka --from-beginning

 

 

三. java 代码

 

生产者

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

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.Properties;
import java.util.Random;
import java.util.UUID;

/**
 * @author admin
 * @title SimpleProducer
 * @projectName KafkaStreamDemo
 * @description TODO
 * @date 2019/9/1016:45
 */
public class SimpleProducer {
    public static void main(String[] args) throws Exception {

        // Assign topicName to string variable
        String topicName = "Hello-Kafka";

        // create instance for properties to access producer configs
        Properties props = new Properties();

        // Assign localhost id, 参考http://kafka.apache.org/documentation/#producerapi
        props.put("bootstrap.servers", "192.168.105.110:9092");

        // Set acknowledgements for producer requests.
        props.put("acks", "all");

        // If the request fails, the producer can automatically retry,
        props.put("retries", 0);

        // Specify buffer size in config
        props.put("batch.size", 16384);

        // Reduce the no of requests less than 0
        props.put("linger.ms", 1);

        // The buffer.memory controls the total amount of memory available to the
        // producer for buffering.
        props.put("buffer.memory", 33554432);

        props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");

        props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");

        Producer<String, String> producer = new KafkaProducer<String, String>(props);


        int i = 0 ;
        while (i < 100) {
            String tempString = UUID.randomUUID().toString();
            System.out.println("----------"+tempString);
            producer.send(new ProducerRecord<String, String>(topicName, tempString));
            Thread.sleep(1000);
            i++ ;
        }

        System.out.println("Message sent successfully");
        producer.close();
    }
}

 

 

 

消费者

 

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.Collections;
import java.util.Properties;

/**
 * @author admin
 * @title SimpleConsumer
 * @projectName KafkaStreamDemo
 * @description TODO
 * @date 2019/9/1016:47
 */
public class SimpleConsumer {
    public static void main(String[] args) throws Exception {
        // Kafka consumer configuration settings
        String topicName = "Hello-Kafka";


        Properties props = new Properties();
        props.put("bootstrap.servers", "192.168.105.110:9092");


        props.put("group.id", "CountryCounter");

        props.put("auto.offset.reset", "latest");

        props.put("enable.auto.commit", "true");

        props.put("auto.commit.interval.ms", "1000");

        props.put("session.timeout.ms", "30000");

        props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        KafkaConsumer<String, String> kafkaConsumer = new KafkaConsumer<String, String>(props);
        // Kafka Consumer subscribes list of topics here.
        kafkaConsumer.subscribe(Collections.singletonList(topicName) );

        while (true) {
            ConsumerRecords<String, String> records = kafkaConsumer.poll(100);
            for (ConsumerRecord<String, String> record : records) {
                // print the offset,key and value for the consumer records.
                System.out.printf("offset = %d, key = %s, value = %s\n", record.offset(), record.key(), record.value());
            }
        }
    }
}