springboot整合kafka

1.需要引入的依赖包

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.kafka</groupId>
        <artifactId>spring-kafka</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.kafka</groupId>
        <artifactId>spring-kafka-test</artifactId>
        <scope>test</scope>
    </dependency>

2. 配置

2.1 kafka存字符串

spring.kafka.bootstrap-servers=192.168.43.122:9092
spring.kafka.producer.buffer-memory=33554432
spring.kafka.producer.acks=all
spring.kafka.producer.retries=1
spring.kafka.producer.key-serializer=org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.value-serializer=org.apache.kafka.common.serialization.StringSerializer
#spring.kafka.producer.value-serializer=org.apache.kafka.common.serialization.ByteArraySerializer
spring.kafka.producer.batch-size=16384


spring.kafka.consumer.auto-commit-interval=100
spring.kafka.consumer.bootstrap-servers=192.168.43.122:9092
spring.kafka.consumer.enable-auto-commit=true
spring.kafka.consumer.group-id=zhsq
spring.kafka.consumer.key-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.StringDeserializer
#spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.ByteArrayDeserializer
spring.kafka.consumer.fetch-min-size=10

2.2  kafka存byte[]

#生产者配置
spring.kafka.bootstrap-servers=192.168.43.122:9092
spring.kafka.producer.buffer-memory=33554432
spring.kafka.producer.acks=all
spring.kafka.producer.retries=1
spring.kafka.producer.key-serializer=org.apache.kafka.common.serialization.StringSerializer
#spring.kafka.producer.value-serializer=org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.value-serializer=org.apache.kafka.common.serialization.ByteArraySerializer
spring.kafka.producer.batch-size=16384

#消费者配置
spring.kafka.consumer.auto-commit-interval=100
spring.kafka.consumer.bootstrap-servers=192.168.43.122:9092
spring.kafka.consumer.enable-auto-commit=true
spring.kafka.consumer.group-id=zhsq
spring.kafka.consumer.key-deserializer=org.apache.kafka.common.serialization.StringDeserializer
#spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.ByteArrayDeserializer
spring.kafka.consumer.fetch-min-size=10

3.生产消费

生产者

package com.netpos.springkafka.Schedule;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import org.springframework.util.concurrent.ListenableFuture;

import java.util.UUID;

@Component
@EnableScheduling
public class KafkaProducer {

    @Autowired
    private KafkaTemplate kafkaTemplate;

    /**
     * 发送字符串
     */
    @Scheduled(cron = "0/1 * * * * ?")
    public void send(){
        String message = UUID.randomUUID().toString();
        ListenableFuture future = kafkaTemplate.send("test", message);
        future.addCallback(o -> System.out.println("send-消息发送成功:" + message), throwable -> System.out.println("消息发送失败:" + message));
    }

    /**
     * 发送byte[]
     */
    @Scheduled(cron = "0/2 * * * * ?")
    public void send_byte(){
        String message = UUID.randomUUID().toString();
        ListenableFuture future = kafkaTemplate.send("test_byte", message.getBytes());
        future.addCallback(o -> System.out.println("send_byte-消息发送成功:" + message), throwable -> System.out.println("消息发送失败:" + message));
    }
}

消费者
package com.netpos.springkafka;

import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;

@Component
public class ConsumerTest {

    //接收字符串
    @KafkaListener(topics = {"test"})
    public void getMessage(ConsumerRecord<String,String> record){
        System.out.println("消费信息"+record.value());
    }

    //接收byte数组
//    @KafkaListener(topics = {"test_byte"})
    public void getMessageByte(ConsumerRecord<String, byte[]> record){
        System.out.println("消费信息"+new String(record.value()));

    }
}

 

 

 

### 关于 Spring Boot 中集成 Kafka 并处理 `null` 值 在 Spring Boot 项目中集成了 Apache Kafka 后,在消息传递过程中可能会遇到发送或接收 `null` 值的情况。对于 Java 编程语言而言,`null` 表示对象引用为空的状态[^1]。 #### 处理生产者端的 `null` 当作为生产者向 Kafka 主题发布消息时,可以设置序列化器来决定如何处理 `null` 值: ```java props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class); props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, JsonSerializer.class); // 自定义序列化逻辑以应对 null 场景 public class NullSafeJsonSerializer<T> implements Serializer<T> { @Override public byte[] serialize(String topic, T data) { if (data == null) { return "null".getBytes(); } try { return new ObjectMapper().writeValueAsBytes(data); } catch (Exception e) { throw new SerializationException("Error serializing JSON message", e); } } } ``` #### 消费者端对 `null` 的处理 消费者接收到消息后,反序列化过程同样需要注意可能出现的 `null` 或特殊字符串 `"null"`: ```java props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class); props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JsonNullAwareDeserializer.class); // 定制化的反序列化类用于识别特定形式的 null 字符串 public class JsonNullAwareDeserializer<T> extends JsonDeserializer<T> { private final Class<T> targetType; public JsonNullAwareDeserializer(Class<T> type) { super(type); this.targetType = type; } @Override protected T deserialize(JsonParser p, DeserializationContext ctxt) throws IOException { String valueAsString = p.getValueAsString(); if ("null".equals(valueAsString)) { return null; // 显式返回 null 而不是尝试实例化目标类型 } return super.deserialize(p, ctxt); } } ```
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