Kafka API编程

1.创建maven项目

2.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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.imooc.spark</groupId>
  <artifactId>sparktrain</artifactId>
  <version>1.0</version>
  <inceptionYear>2008</inceptionYear>
  <properties>
    <scala.version>2.11.8</scala.version>
    <kafka.version>0.10.2.2</kafka.version>
  </properties>


  <dependencies>
    <dependency>
      <groupId>org.scala-lang</groupId>
      <artifactId>scala-library</artifactId>
      <version>${scala.version}</version>
    </dependency>

    <!--Kafka依赖-->
    <dependency>
      <groupId>org.apache.kafka</groupId>
      <artifactId>kafka_2.11</artifactId>
      <version>${kafka.version}</version>
    </dependency>


  </dependencies>

  <build>
    <sourceDirectory>src/main/scala</sourceDirectory>
    <testSourceDirectory>src/test/scala</testSourceDirectory>
    <plugins>
      <plugin>
        <groupId>org.scala-tools</groupId>
        <artifactId>maven-scala-plugin</artifactId>
        <executions>
          <execution>
            <goals>
              <goal>compile</goal>
              <goal>testCompile</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <scalaVersion>${scala.version}</scalaVersion>
          <args>
            <arg>-target:jvm-1.5</arg>
          </args>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-eclipse-plugin</artifactId>
        <configuration>
          <downloadSources>true</downloadSources>
          <buildcommands>
            <buildcommand>ch.epfl.lamp.sdt.core.scalabuilder</buildcommand>
          </buildcommands>
          <additionalProjectnatures>
            <projectnature>ch.epfl.lamp.sdt.core.scalanature</projectnature>
          </additionalProjectnatures>
          <classpathContainers>
            <classpathContainer>org.eclipse.jdt.launching.JRE_CONTAINER</classpathContainer>
            <classpathContainer>ch.epfl.lamp.sdt.launching.SCALA_CONTAINER</classpathContainer>
          </classpathContainers>
        </configuration>
      </plugin>
    </plugins>
  </build>
  <reporting>
    <plugins>
      <plugin>
        <groupId>org.scala-tools</groupId>
        <artifactId>maven-scala-plugin</artifactId>
        <configuration>
          <scalaVersion>${scala.version}</scalaVersion>
        </configuration>
      </plugin>
    </plugins>
  </reporting>
</project>

2.kafka常用配置文件 KafkaProperties

/**
 * kafka常用配置文件
 */
public class KafkaProperties {

public static final String ZK="192.168.218.129:2181";

public static final  String TOPIC="hello_topic";

public static final String BROKER_LIST="192.168.218.129:9092";

public static final String GROUP_ID="test_group1";


}

3.生产者

import kafka.javaapi.producer.Producer;
import kafka.producer.KeyedMessage;
import kafka.producer.ProducerConfig;

import java.util.Properties;

/**
 * Kafka生产者
 */
public class KafkaProducer extends Thread{

    private String topic;

    private Producer<Integer, String> producer;

    public KafkaProducer(String topic) {
        this.topic = topic;

        Properties properties = new Properties();

        properties.put("metadata.broker.list",KafkaProperties.BROKER_LIST);
        properties.put("serializer.class","kafka.serializer.StringEncoder");
        properties.put("request.required.acks","1");

        producer = new Producer<Integer, String>(new ProducerConfig(properties));
    }


    @Override
    public void run() {

        int messageNo = 1;

        while(true) {
            String message = "message_" + messageNo;
            producer.send(new KeyedMessage<Integer, String>(topic, message));
            System.out.println("Sent: " + message);

            messageNo ++ ;

            try{
                Thread.sleep(2000);
            } catch (Exception e){
                e.printStackTrace();
            }
        }

    }
}

request.required.ack = 0 -表示生产者不会等待领导者的任何确认。
request.required.ack = 1 -表示leader将消息写入本地日志并立即确认
request.required.ack = -1 -表示领导者将等待所有同步副本的确认，然后才确认写入

4.test

/**
 * kafka java api 测试
 */
public class KafkaClientApp {

    public static void main(String[] args) {
        new KafkaProducer(KafkaProperties.TOPIC).start();

        //new KafkaConsumer(KafkaProperties.TOPIC).start();
    }
}

5.消费者

import kafka.consumer.Consumer;
import kafka.consumer.ConsumerConfig;
import kafka.consumer.ConsumerIterator;
import kafka.consumer.KafkaStream;
import kafka.javaapi.consumer.ConsumerConnector;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

/**
 * Kafka消费者
 */
public class KafkaConsumer extends Thread{

    private String topic;

    public KafkaConsumer(String topic) {
        this.topic = topic;
    }


    private ConsumerConnector createConnector(){
        Properties properties = new Properties();
        properties.put("zookeeper.connect", KafkaProperties.ZK);
        properties.put("group.id",KafkaProperties.GROUP_ID);
        return Consumer.createJavaConsumerConnector(new ConsumerConfig(properties));
    }

    @Override
    public void run() {
        ConsumerConnector consumer = createConnector();

        Map<String, Integer> topicCountMap = new HashMap<String, Integer>();
        topicCountMap.put(topic, 1);
//        topicCountMap.put(topic2, 1);
//        topicCountMap.put(topic3, 1);

        // String: topic
        // List<KafkaStream<byte[], byte[]>>  对应的数据流
        Map<String, List<KafkaStream<byte[], byte[]>>> messageStream =  consumer.createMessageStreams(topicCountMap);

        KafkaStream<byte[], byte[]> stream = messageStream.get(topic).get(0);   //get(0)获取我们每次接收到的数据

        ConsumerIterator<byte[], byte[]> iterator = stream.iterator();


        while (iterator.hasNext()) {
            String message = new String(iterator.next().message());
            System.out.println("rec: " + message);
        }
    }
}