??本篇博主帶來(lái)的是Kafka的Producer API操作。

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1. 消息發(fā)送流程

??Kafka的Producer發(fā)送消息采用的是異步發(fā)送的方式。在消息發(fā)送的過(guò)程中，涉及到了兩個(gè)線程——main線程和Sender線程，以及一個(gè)線程共享變量——RecordAccumulator。main線程將消息發(fā)送給RecordAccumulator，Sender線程不斷從RecordAccumulator中拉取消息發(fā)送到Kafka broker。

下圖為KafkaProducer發(fā)送消息流程


相關(guān)參數(shù)：
batch.size：只有數(shù)據(jù)積累到batch.size之后，sender才會(huì)發(fā)送數(shù)據(jù)。
linger.ms：如果數(shù)據(jù)遲遲未達(dá)到batch.size，sender等待linger.time之后就會(huì)發(fā)送數(shù)據(jù)。

2. 無(wú)回調(diào)參數(shù)的API

• 1. 導(dǎo)入依賴

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
        </plugins>

    </build>


    <dependencies>
    <dependency>
        <groupId>org.apache.kafka</groupId>
        <artifactId>kafka-clients</artifactId>
        <version>0.11.0.2</version>
    </dependency>
    </dependencies>

• 2. 編寫代碼

需要用到的類：
KafkaProducer：需要?jiǎng)?chuàng)建一個(gè)生產(chǎn)者對(duì)象，用來(lái)發(fā)送數(shù)據(jù)
ProducerConfig：獲取所需的一系列配置參數(shù)
ProducerRecord：每條數(shù)據(jù)都要封裝成一個(gè)ProducerRecord對(duì)象

• 3. 完整代碼

package com.buwenbuhuo.kafka.producer;

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

import java.util.Properties;
import java.util.concurrent.ExecutionException;


/**
 * @author 卜溫不火
 * @create 2020-05-06 20:21
 * com.buwenbuhuo.kafka.producer - the name of the target package where the new class or interface will be created.
 * kafka0506 - the name of the current project.
 */
public class CustomProducer {

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        Properties props = new Properties();
        props.put("bootstrap.servers", "hadoop002:9092");//kafka集群，broker-list
        props.put("acks", "all");
        props.put("retries", 1);//重試次數(shù)
        props.put("batch.size", 16384);//批次大小
        props.put("linger.ms", 1);//等待時(shí)間
        props.put("buffer.memory", 33554432);//RecordAccumulator緩沖區(qū)大小
        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<>(props);
        for (int i = 0; i < 100; i++) {
            producer.send(new ProducerRecord<String, String>("second", i + "", "my name is bu wen bu huo -" + i));
        }
        producer.close();
    }
}

• 4. 群起zookeeper和kafka

[bigdata@hadoop002 zookeeper-3.4.10]$ bin/start-allzk.sh 
[bigdata@hadoop002 kafka]$ bin/start-kafkaall.sh 

• 5. 啟動(dòng)一個(gè)consumer控制臺(tái)

[bigdata@hadoop002 kafka]$ bin/kafka-console-consumer.sh --bootstrap-server hadoop002:9092 --topic first

• 6. 跑代碼進(jìn)行測(cè)試
  

為什么是無(wú)序的，這是因?yàn)槲覀冎荒鼙ＷC分區(qū)內(nèi)有序。其他無(wú)序。

3. 帶回調(diào)函數(shù)的API

??回調(diào)函數(shù)會(huì)在producer收到ack時(shí)調(diào)用，為異步調(diào)用，該方法有兩個(gè)參數(shù)，分別是RecordMetadata和Exception，如果Exception為null，說(shuō)明消息發(fā)送成功，如果Exception不為null，說(shuō)明消息發(fā)送失敗。
??注意：消息發(fā)送失敗會(huì)自動(dòng)重試，不需要我們?cè)诨卣{(diào)函數(shù)中手動(dòng)重試。

• 1. 代碼

package com.buwenbuhuo.kafka.producer;

import org.apache.kafka.clients.producer.*;
import org.apache.kafka.common.serialization.StringSerializer;

import java.util.Properties;


/**
 * @author 卜溫不火
 * @create 2020-05-06 20:21
 * com.buwenbuhuo.kafka.producer - the name of the target package where the new class or interface will be created.
 * kafka0506 - the name of the current project.
 */
public class CustomProducer {

    public static void main(String[] args) {

        Properties props = new Properties();
        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "hadoop002:9092");
        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());

        props.put(ProducerConfig.ACKS_CONFIG, "all");
        props.put(ProducerConfig.BATCH_SIZE_CONFIG, 16384);
        props.put(ProducerConfig.LINGER_MS_CONFIG, 1);


        //1.創(chuàng)建1個(gè)生產(chǎn)者對(duì)象
        KafkaProducer<String, String> producer = new KafkaProducer<>(props);

        //2.調(diào)用send方法
        for (int i = 0; i < 1000; i++) {
            producer.send(new ProducerRecord<String, String>("second", i + "", "message-" + i), (metadata,exception)->{

                if(exception==null){
                    System.out.println("success"+metadata.topic()+"-"+metadata.partition()+"-"+metadata.offset());
                }else{
                    exception.printStackTrace();
                }
            });
        }

        //3.關(guān)閉生產(chǎn)者
        producer.close();
    }
}

• 2. 結(jié)果

• 3. 大致流程圖
  

4. 同步發(fā)送API / 只是比異步多了一個(gè).get()

??同步發(fā)送的意思就是，一條消息發(fā)送之后，會(huì)阻塞當(dāng)前線程，直至返回ack。
??由于send方法返回的是一個(gè)Future對(duì)象，根據(jù)Futrue對(duì)象的特點(diǎn)，我們也可以實(shí)現(xiàn)同步發(fā)送的效果，只需在調(diào)用Future對(duì)象的get方發(fā)即可。

• 1. 代碼：

package com.buwenbuhuo.kafka.producer;

import org.apache.kafka.clients.producer.*;
import java.util.Properties;
import java.util.concurrent.ExecutionException;

/**
 * @author 卜溫不火
 * @create 2020-05-06 20:21
 * com.buwenbuhuo.kafka.producer - the name of the target package where the new class or interface will be created.
 * kafka0506 - the name of the current project.
 */
public class CustomProducer {

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        Properties props = new Properties();
        props.put("bootstrap.servers", "hadoop002:9092");//kafka集群，broker-list
        props.put("acks", "all");
        props.put("retries", 1);//重試次數(shù)
        props.put("batch.size", 16384);//批次大小
        props.put("linger.ms", 1);//等待時(shí)間
        props.put("buffer.memory", 33554432);//RecordAccumulator緩沖區(qū)大小
        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<>(props);
        for (int i = 0; i < 100; i++) {
            producer.send(new ProducerRecord<String, String>("second", i + "", "my name is bu wen bu huo -" + i)).get();
        }
        producer.close();
    }
}

• 2. 結(jié)果
  
  ??本次的分享就到這里了,

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?? 看 完 就 贊 ， 養(yǎng) 成 習(xí) 慣 ！ ！ ！ color{#FF0000}{看完就贊，養(yǎng)成習(xí)慣?。。 看完就贊，養(yǎng)成習(xí)慣！！！^ _ ^ ?? ?? ??
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