|NO.Z.00031|——————————|BigDataEnd|——|Hadoop&kafka.V16|——|kafka.v16|自定义反序列化|

一、自定义反序列化

### --- 创建一个maven项目：demo-08-customDeserializer
~~~     # 添加pom.xml依赖

    <dependencies>
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka-clients</artifactId>
            <version>1.0.2</version>
        </dependency>
    </dependencies>

二、自定义反序列化代码实现

### --- 自定义反序列化类，需要实现org.apache.kafka.common.serialization.Deserializer 接口。
~~~     # com.yanqi.kafka.demo.deserializer.UserDeserializer

package com.yanqi.kafka.demo.deserializer;

import com.yanqi.kafka.demo.entity.User;
import org.apache.kafka.common.serialization.Deserializer;

import java.nio.ByteBuffer;
import java.util.Map;

public class UserDeserializer implements Deserializer<User> {
    @Override
    public void configure(Map<String, ?> configs, boolean isKey) {

    }

    @Override
    public User deserialize(String topic, byte[] data) {
        ByteBuffer buffer = ByteBuffer.allocate(data.length);

        buffer.put(data);
        buffer.flip();

        final int userId = buffer.getInt();
        final int usernameLength = buffer.getInt();

        String username = new String(data, 8, usernameLength);

        return new User(userId, username);
    }

    @Override
    public void close() {

    }
}

### --- com.yanqi.kafka.demo.consumer.MyConsumer

package com.yanqi.kafka.demo.consumer;

import com.yanqi.kafka.demo.deserializer.UserDeserializer;
import com.yanqi.kafka.demo.entity.User;
import org.apache.kafka.clients.consumer.ConsumerConfig;
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.serialization.StringDeserializer;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Consumer;

public class UserConsumer {

    public static void main(String[] args) {
        Map<String, Object> configs = new HashMap<>();
        configs.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "node1:9092");
        configs.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        // 设置自定义的反序列化器
        configs.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, UserDeserializer.class);

        configs.put(ConsumerConfig.GROUP_ID_CONFIG, "user_consumer");
        configs.put(ConsumerConfig.CLIENT_ID_CONFIG, "consumer_id");
        configs.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");

        KafkaConsumer<String, User> consumer = new KafkaConsumer<String, User>(configs);

        // 订阅主题
        consumer.subscribe(Collections.singleton("tp_user_01"));

        final ConsumerRecords<String, User> records = consumer.poll(Long.MAX_VALUE);

        records.forEach(new Consumer<ConsumerRecord<String, User>>() {
            @Override
            public void accept(ConsumerRecord<String, User> record) {
                System.out.println(record.value());
            }
        });

        // 关闭消费者
        consumer.close();

    }

}

### --- com.yanqi.kafka.demo.entity.User

package com.yanqi.kafka.demo.entity;

/**
 * 用户自定义的封装消息的实体类
 */
public class User {
    private Integer userId;
    private String username;

    public User() {
    }

    public User(Integer userId, String username) {
        this.userId = userId;
        this.username = username;
    }

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    @Override
    public String toString() {
        return "User{" +
                "userId=" + userId +
                ", username='" + username + '\'' +
                '}';
    }
}

三、编译打印

### --- 查看主题是否创建

[root@hadoop ~]# kafka-topics.sh --zookeeper localhost:2181/myKafka --list
tp_user_01

### --- 打开消费消息，等待消息消费

[root@hadoop ~]# kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic tp_user_01 --from-beginning
张三
赵四
赵四

### --- 编译打印：UserConsumer

D:\JAVA\jdk1.8.0_231\bin\java.exe "-javaagent:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53798:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath D:\JAVA\jdk1.8.0_231\jre\lib\charsets.jar;D:\JAVA\jdk1.8.0_231\jre\lib\deploy.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\access-bridge-64.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\cldrdata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\dnsns.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jaccess.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jfxrt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\localedata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\nashorn.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunec.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunjce_provider.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunmscapi.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunpkcs11.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\zipfs.jar;D:\JAVA\jdk1.8.0_231\jre\lib\javaws.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jce.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfr.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfxswt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jsse.jar;D:\JAVA\jdk1.8.0_231\jre\lib\management-agent.jar;D:\JAVA\jdk1.8.0_231\jre\lib\plugin.jar;D:\JAVA\jdk1.8.0_231\jre\lib\resources.jar;D:\JAVA\jdk1.8.0_231\jre\lib\rt.jar;E:\NO.Z.10000——javaproject\NO.Z.00002.Hadoop\kafka_demo\demo-08-kafka-customDeserializer\target\classes;C:\Users\Administrator\.m2\repository\org\apache\kafka\kafka-clients\1.0.2\kafka-clients-1.0.2.jar;C:\Users\Administrator\.m2\repository\org\lz4\lz4-java\1.4\lz4-java-1.4.jar;C:\Users\Administrator\.m2\repository\org\xerial\snappy\snappy-java\1.1.4\snappy-java-1.1.4.jar;C:\Users\Administrator\.m2\repository\org\slf4j\slf4j-api\1.7.25\slf4j-api-1.7.25.jar com.yanqi.kafka.demo.consumer.UserConsumer
User{userId=1001, username='张三'}
User{userId=400, username='赵四'}
User{userId=400, username='赵四'}

四、通过生成者在生产一个消息：

### --- 使用生成者生产一个消息：com.yanqi.kafka.demo.producer.MyProducer

[root@hadoop ~]# kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic tp_user_01 --from-beginning
张三
赵四
赵四
~~生产者生产的消息
李四
赵四

### --- 通过UserConsumer消费消息

D:\JAVA\jdk1.8.0_231\bin\java.exe "-javaagent:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=62541:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath D:\JAVA\jdk1.8.0_231\jre\lib\charsets.jar;D:\JAVA\jdk1.8.0_231\jre\lib\deploy.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\access-bridge-64.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\cldrdata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\dnsns.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jaccess.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jfxrt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\localedata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\nashorn.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunec.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunjce_provider.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunmscapi.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunpkcs11.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\zipfs.jar;D:\JAVA\jdk1.8.0_231\jre\lib\javaws.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jce.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfr.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfxswt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jsse.jar;D:\JAVA\jdk1.8.0_231\jre\lib\management-agent.jar;D:\JAVA\jdk1.8.0_231\jre\lib\plugin.jar;D:\JAVA\jdk1.8.0_231\jre\lib\resources.jar;D:\JAVA\jdk1.8.0_231\jre\lib\rt.jar;E:\NO.Z.10000——javaproject\NO.Z.00002.Hadoop\kafka_demo\demo-08-kafka-customDeserializer\target\classes;C:\Users\Administrator\.m2\repository\org\apache\kafka\kafka-clients\1.0.2\kafka-clients-1.0.2.jar;C:\Users\Administrator\.m2\repository\org\lz4\lz4-java\1.4\lz4-java-1.4.jar;C:\Users\Administrator\.m2\repository\org\xerial\snappy\snappy-java\1.1.4\snappy-java-1.1.4.jar;C:\Users\Administrator\.m2\repository\org\slf4j\slf4j-api\1.7.25\slf4j-api-1.7.25.jar com.yanqi.kafka.demo.consumer.UserConsumer
User{userId=400, username='李四'}
User{userId=400, username='赵四'}

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Walter Savage Landor:strove with none,for none was worth my strife.Nature I loved and, next to Nature, Art:I warm'd both hands before the fire of life.It sinks, and I am ready to depart

                                                                                                                                                   ——W.S.Landor

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