From 26fd715128501924feb9c056f785db33e2ecbb71 Mon Sep 17 00:00:00 2001
From: Kai Moritz <kai@juplo.de>
Date: Mon, 18 Jul 2022 21:20:10 +0200
Subject: [PATCH] splitter: 1.0.0-spring-ingetration - extract the key on the
inbound channel
* The key of the Kafka-Message is extracted on the inbound channel with
a `HeaderEnricher`.
* This way, the key is propagated to dreived messages automatically.
---
.../splitter/SplitterApplication.java | 25 +++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/src/main/java/de/juplo/kafka/wordcount/splitter/SplitterApplication.java b/src/main/java/de/juplo/kafka/wordcount/splitter/SplitterApplication.java
index 3828050..8bd928b 100644
--- a/src/main/java/de/juplo/kafka/wordcount/splitter/SplitterApplication.java
+++ b/src/main/java/de/juplo/kafka/wordcount/splitter/SplitterApplication.java
@@ -9,16 +9,23 @@ import org.springframework.expression.ExpressionParser;
import org.springframework.expression.common.LiteralExpression;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.integration.annotation.ServiceActivator;
+import org.springframework.integration.annotation.Transformer;
import org.springframework.integration.config.EnableIntegration;
import org.springframework.integration.core.MessageProducer;
import org.springframework.integration.kafka.inbound.KafkaMessageDrivenChannelAdapter;
import org.springframework.integration.kafka.outbound.KafkaProducerMessageHandler;
+import org.springframework.integration.transformer.HeaderEnricher;
+import org.springframework.integration.transformer.support.ExpressionEvaluatingHeaderValueMessageProcessor;
+import org.springframework.integration.transformer.support.HeaderValueMessageProcessor;
import org.springframework.kafka.core.ConsumerFactory;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.kafka.listener.ContainerProperties;
import org.springframework.kafka.listener.KafkaMessageListenerContainer;
import org.springframework.messaging.MessageHandler;
+import java.util.HashMap;
+import java.util.Map;
+
@SpringBootApplication
@EnableConfigurationProperties(SplitterApplicationProperties.class)
@@ -31,10 +38,24 @@ public class SplitterApplication
{
KafkaMessageDrivenChannelAdapter<String, String> adapter =
new KafkaMessageDrivenChannelAdapter(messageListenerContainer);
- adapter.setOutputChannelName("recordings");
+ adapter.setOutputChannelName("kafka-in");
return adapter;
}
+ @Bean
+ @Transformer(inputChannel = "kafka-in", outputChannel = "recordings")
+ public HeaderEnricher kafkaInHeaderEnricher()
+ {
+ Map<String, HeaderValueMessageProcessor<?>> headersToAdd = new HashMap<>();
+ Expression expression =
+ new SpelExpressionParser().parseExpression("headers['kafka_receivedMessageKey']");
+ headersToAdd.put(
+ "key",
+ new ExpressionEvaluatingHeaderValueMessageProcessor<>(expression, String.class));
+ HeaderEnricher enricher = new HeaderEnricher(headersToAdd);
+ return enricher;
+ }
+
@Bean
KafkaMessageListenerContainer<String, String> messageListenerContainer(
ConsumerFactory<String,String> consumerFactory,
@@ -56,7 +77,7 @@ public class SplitterApplication
new KafkaProducerMessageHandler<>(kafkaTemplate);
handler.setTopicExpression(new LiteralExpression(properties.getOutputTopic()));
final ExpressionParser parser = new SpelExpressionParser();
- Expression expression = parser.parseExpression("headers['kafka_receivedMessageKey']");
+ Expression expression = parser.parseExpression("headers['key']");
handler.setMessageKeyExpression(expression);
return handler;
}
--
2.20.1