在 Kafka 中,延迟队列的实现通常依赖于第三方库,例如 kafka-delayed-message-consumer
或 spring-kafka-delay
kafka-delayed-message-consumer
库:首先,将 kafka-delayed-message-consumer
库添加到项目的依赖中。对于 Maven 项目,可以在 pom.xml
文件中添加以下依赖:
<dependency>
<groupId>com.github.sgroschupf</groupId>
<artifactId>kafka-delayed-message-consumer</artifactId>
<version>0.3.1</version>
</dependency>
接下来,创建一个消费者配置类,并设置延迟消息的阈值:
import com.github.sgroschupf.kafka.connect.delayed.DelayedMessageConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.common.serialization.StringDeserializer;
import java.util.HashMap;
import java.util.Map;
public class DelayedMessageConsumerConfigExample {
public static Map<String, Object> createDelayedMessageConsumerConfig(String bootstrapServers, String groupId, long delayThreshold) {
Map<String, Object> props = new HashMap<>();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
props.put(DelayedMessageConsumerConfig.DELAY_MAX_MS_CONFIG, delayThreshold);
props.put(DelayedMessageConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, false);
return props;
}
}
在这个例子中,delayThreshold
参数用于设置延迟消息的阈值(以毫秒为单位)。
spring-kafka-delay
库:首先,将 spring-kafka-delay
库添加到项目的依赖中。对于 Maven 项目,可以在 pom.xml
文件中添加以下依赖:
<dependency>
<groupId>org.springframework.kafka</groupId>
<artifactId>spring-kafka-support</artifactId>
<version>2.7.0</version>
</dependency>
接下来,创建一个消费者配置类,并设置延迟消息的阈值:
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.springframework.kafka.config.ConcurrentKafkaListenerContainerFactory;
import org.springframework.kafka.core.ConsumerFactory;
import org.springframework.kafka.listener.config.MethodKafkaListenerEndpointRegistrar;
import org.springframework.kafka.listener.config.KafkaListenerEndpointRegistrarBean;
import java.util.HashMap;
import java.util.Map;
public class DelayedMessageConsumerConfigExample {
public static Map<String, Object> createDelayedMessageConsumerConfig(String bootstrapServers, String groupId, long delayThreshold) {
Map<String, Object> props = new HashMap<>();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
ConcurrentKafkaListenerContainerFactory<String, String> factory = new ConcurrentKafkaListenerContainerFactory<>();
factory.setConsumerFactory(createConsumerFactory(props));
KafkaListenerEndpointRegistrarBean<String, String> registrar = new KafkaListenerEndpointRegistrarBean<>(factory);
registrar.setEndpointRegistry(new DefaultEndpointRegistry());
return props;
}
private static ConsumerFactory<String, String> createConsumerFactory(Map<String, Object> props) {
return new DefaultKafkaConsumerFactory<>(props);
}
}
在这个例子中,delayThreshold
参数用于设置延迟消息的阈值(以毫秒为单位)。
请注意,这两个示例仅用于演示如何设置延迟消息的阈值。在实际应用中,您可能需要根据具体需求对这些示例进行调整。