Kafka系列三 java API操作

使用java API操作kafka

1.pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>cn.itcast</groupId>
    <artifactId>KafkaDemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.apache.kafka/kafka -->
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka_2.12</artifactId>
            <version>1.0.0</version>
        </dependency>
    </dependencies>
</project>

 2.producer和consumer配置文件

　　2.1producer.properties

#请求时候需要验证
acks=all
#请求失败时候需要重试
retries=0
#内存缓存区大小
buffer.memory=33554432
#分区类
partitioner.class=org.apache.kafka.clients.producer.internals.DefaultPartitioner
#broker地址
bootstrap.servers=192.168.25.151:9092,192.168.25.152:9092,192.168.25.153:9092
#指定消息key序列化方式
key.serializer=org.apache.kafka.common.serialization.StringSerializer
#指定消息本身的序列化方式
value.serializer=org.apache.kafka.common.serialization.StringSerializer

　　2.2consumer.properties

#每个消费者分配独立的组号
group.id=test
#如果value合法，则自动提交偏移量
enable.auto.commit=true
#设置多久一次更新被消费消息的偏移量
auto.commit.interval.ms=1000
#设置会话响应的时间，超过这个时间kafka可以选择放弃消费或者消费下一条消息
session.timeout.ms=30000
#指定消息key序列化方式
key.deserializer=org.apache.kafka.common.serialization.StringDeserializer
#指定消息本身的序列化方式
value.deserializer=org.apache.kafka.common.serialization.StringDeserializer
#broker地址
bootstrap.servers=192.168.25.151:9092,192.168.25.152:9092,192.168.25.153:9092

3.生产者和消费者代码

　　3.1 KafkaProducerSimple.java

package cn.itcast.kafka;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.util.UUID;

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

public class KafkaProducerSimple {
    public static void main(String[] args) throws IOException {
        Properties properties = new Properties();
        InputStream inStream = KafkaProducerSimple.class.getClassLoader().getResourceAsStream("producer.properties");

        properties.load(inStream);

        Producer<String, String> producer = new KafkaProducer<>(properties);
        String TOPIC = "orderMq6";
        for (int messageNo = 1; messageNo < 10000; messageNo++) {
            producer.send(new ProducerRecord<String, String>(TOPIC,messageNo + "", UUID.randomUUID() + "itcast"));
        }
    }
}

　　3.2 KafkaConsumerSimple.java

package cn.itcast.kafka;

import java.io.InputStream;
import java.util.Arrays;
import java.util.Properties;

import org.apache.kafka.clients.consumer.Consumer;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;

public class KafkaConsumerSimple {

    public static void main(String[] args) throws Exception {
        Properties properties = new Properties();
        InputStream inStream = KafkaConsumerSimple.class.getClassLoader().getResourceAsStream("consumer.properties");
        properties.load(inStream);
        Consumer<String, String> consumer = new KafkaConsumer<>(properties);
        consumer.subscribe(Arrays.asList("orderMq6"));
        while (true) {
            ConsumerRecords<String, String> records = consumer.poll(100);
            if (records.count() > 0) {
                for (ConsumerRecord<String, String> record : records) {
                    System.out.println(record.value());
                }

            }
        }
    }
}

　　以上代码如果执行超时，必须在本地host文件中配置broker的hostname和ip的映射。