关于后端:kafka学习第一步安装环境以及我们的第一个相关代码

kafka学习

windows 上的kafka学习和装置相干的问题

一. 下载kafka

kafka应用java实现并且官网提供了windows的反对,所以间接下载就完事了,将其解压到一个文件夹下,如我在D:\kafka,这里版本是3.20,其余版本可能会有点不同.整体门路如下,别离是

  • bin: 提供的一些曾经写好了的shell命令文件和windows上面的bat文件
  • config: 一些曾经配置好的文件,如kafka server的配置,zookeeper的配置,consumer和producer的配置
  • libs: jar包和一些依赖
  • licenses: 开源协定证书

二. 启动kafka 单实例

激动人心的时刻来了,咱们下载了文件,装置了jdk环境(个别都会有环境吧),而后设置properties文件,在这里我轻易贴一下要留神的properties文件,定义了前面须要用的端口:

# file:config/server.properties
listeners=PLAINTEXT://127.0.0.1:9092 # 指定端口
log.dirs=E:\\kafka-logs-1 # 我感觉指定个文件夹比拟好
zookeeper.connect=localhost:2181 # 指定zookeeper服务器
# file:config/zookeeper.properties
dataDir=E:\\zookeeper
# the port at which the clients will connect
clientPort=2181

1. 启动zookeeper

.\bin\windows\zookeeper-server-start.bat .\config\zookeeper.properties
# 如果应用wsl或者bash上面
.\bin\zookeeper-server-start.sh .\config\zookeeper.properties

2. 启动kafka

.\bin\windows\kafka-server-start.bat .\config\server.properties
# 如果应用wsl或者bash上面
.\bin\kafka-server-start.sh .\config\zookeeper.properties

这样子就算是启动胜利了,并且能够看到启动的实例连贯的zookeeper和broker提供的ip.

3. 创立topic

# 老版本应用zookeeper-server 确定对应的kafka集群,然而新版本应用bootstrap-server确定连贯的集群
.\bin\windows\kafka-topics --create --bootstrap-server 127.0.0.1:9092 --topic test

咱们查看当初的集群里的topic状况能够应用上面的命令:

.\bin\windows\kafka-topics --describe --bootstrap-server 127.0.0.1:9092

能够看到自身实际上存在一个top叫做__consumer_=offsets去保留对应的consumer的offeset数据

4. 向topic写入数据和读取数据

.\bin\windows\kafka-console-producer --bootstrap-server 127.0.0.1:9092 --topic test1

输出日志数据,之后再读出来

 .\bin\windows\kafka-console-consumer.bat --topic test1 --bootstrap-server 127.0.0.1:9093 # --from-beginning 能够看到当初还保留的音讯

那么至此咱们就实现了最根本的kafka的操作,创立主题\写入数据\读出数据

三. 编写本人的代码

1. 编写本人的producer

依据kafka自身的教程,kafka-clients自身提供了三个send模式,别离是阻塞和非阻塞以及实现好了的future回调.

package com.lixiande.kafkaLearn;

import org.apache.kafka.clients.producer.Callback;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Date;
import java.util.Properties;
import java.util.concurrent.Future;

public class Producer {
    Logger logger = LoggerFactory.getLogger(Producer.class);
    private Properties kafkaProducerProps;
    private KafkaProducer kafkaProducer;

    public static void main(String[] args) {
        Producer producer = new Producer();
        try {
            while (true) {
                producer.SendCallBack("test", "what fuck about key value", "this is nothing about kafka and send with Callback" + new Date().toString());
                producer.SendBlock("test", "what fuck about key value", "this is nothing about kafka and send by blocking" + new Date().toString());
                producer.SendAsync("test", "what fuck about key value", "this is nothing about kafka and send by async" + new Date().toString());
            }
        } finally {
            producer.kafkaProducer.close();
        }

    }

    public void SendBlock(String topic, String key, String value) {
        try {
            System.out.println("block send :" + kafkaProducer.send(new ProducerRecord<String, String>(topic, key, value)).get().toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public Future SendAsync(String topic, String key, String value) {
        return kafkaProducer.send(new ProducerRecord<String, String>(topic, key, value));
    }

    public void SendCallBack(String topic, String key, String value) {
        kafkaProducer.send(new ProducerRecord<String, String>(topic, key, value), new Callback() {
            @Override
            public void onCompletion(RecordMetadata recordMetadata, Exception e) {
                System.out.println(recordMetadata.toString());
                if (e != null)
                    System.out.println(e.toString());
            }
        });
    }

    public Producer() {
        kafkaProducerProps = new Properties();
        kafkaProducerProps.put("key.serializer", org.apache.kafka.common.serialization.StringSerializer.class.getName());
        kafkaProducerProps.put("value.serializer", org.apache.kafka.common.serialization.StringSerializer.class.getName());
        kafkaProducerProps.put("bootstrap.servers", "127.0.0.1:9092");
        kafkaProducer = new KafkaProducer<String, String>(kafkaProducerProps);
    }
}

2.编写本人的consumer

同样的consumer也是能够有很多种形式,比方订阅topic,订阅topic外面的某些partition,以及订阅正则匹配的topics

package com.lixiande.kafkaLearn;

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.PartitionInfo;
import org.apache.kafka.common.errors.WakeupException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.*;

public class Consumer {
    private static Logger logger = LoggerFactory.getLogger(Consumer.class);
    private KafkaConsumer kafkaConsumer;
    private Properties kafkaConsumerProps;

    private Map<String, Integer> consumeMap;

    public static void main(String[] args) {
        Consumer consumer = new Consumer();
        Thread mainThread = Thread.currentThread();
        Runtime.getRuntime().addShutdownHook(new Thread(() -> {
            System.out.println("consumer starting exiting");
            consumer.kafkaConsumer.wakeup();
            try {
                mainThread.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }));
        consumer.listen();
    }

    public Consumer() {
        kafkaConsumerProps = new Properties();
        kafkaConsumerProps.put("bootstrap.servers", "127.0.0.1:9092");
        kafkaConsumerProps.put("key.deserializer", org.apache.kafka.common.serialization.StringDeserializer.class.getName());
        kafkaConsumerProps.put("value.deserializer", org.apache.kafka.common.serialization.StringDeserializer.class.getName());
        kafkaConsumerProps.put("group.id", "loopConsumer");
        kafkaConsumer = new KafkaConsumer<String, String>(kafkaConsumerProps);
        kafkaConsumer.subscribe(Collections.singletonList("test"));
        // kafkaConsumer.subscribe(Pattern.compile("test*")); // 也能够订阅所有的test*的主题
        List<PartitionInfo> partitionInfoList = kafkaConsumer.partitionsFor("test");
        // XXX:这里能够用于获取特定的topic的分区,从而实现不同的消费者手动调配,而不会走平衡
        /*
        // if (partitionInfoList != null){
        //     for (PartitionInfo info : partitionInfoList){
        //         partitions.add(new TopicPartition(info.topic(), info.partition()));
        //     }
        //     kafkaConsumer.assign(partitions);
        // }
        */
        consumeMap = new HashMap<>();
    }

    public void listen() {
        try {
            while (true) {
                ConsumerRecords<String, String> records = kafkaConsumer.poll(100);
                for (ConsumerRecord<String, String> record : records) {
                    logger.warn(record.toString());
                    int updatedCount = 1;
                    if (consumeMap.containsValue(record.value())) {
                        updatedCount = consumeMap.get(record.value()) + 1;
                    }
                    consumeMap.put(record.value(), updatedCount);
                }
                System.out.println("\n-------------------------------------------------\n");
                System.out.println(consumeMap);
                System.out.println("\n-------------------------------------------------\n");
                consumeMap.clear();
                kafkaConsumer.commitAsync();
            }
        } catch (WakeupException e) {
        } finally {
            kafkaConsumer.close();
            System.out.println("Closed Consumer and we are done");
        }
    }

}

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