From 7b017bc9954ecf26af755d43dd02999468cd94ea Mon Sep 17 00:00:00 2001
From: Kai Moritz <kai@juplo.de>
Date: Sun, 26 Jun 2022 18:07:32 +0200
Subject: [PATCH] splitter: 1.0.0-spring-integration - Added the key of the
 incoming message

* Added a `ChannelInterceptor`, that copies the key from the received
  message to the outgoing message.
* This fixes the test.
---
 .../splitter/SplitterApplication.java         | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)

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 412f429..0a70551 100644
--- a/src/main/java/de/juplo/kafka/wordcount/splitter/SplitterApplication.java
+++ b/src/main/java/de/juplo/kafka/wordcount/splitter/SplitterApplication.java
@@ -7,13 +7,20 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.expression.common.LiteralExpression;
 import org.springframework.integration.annotation.InboundChannelAdapter;
 import org.springframework.integration.annotation.ServiceActivator;
+import org.springframework.integration.channel.DirectChannel;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.kafka.inbound.KafkaMessageSource;
 import org.springframework.integration.kafka.outbound.KafkaProducerMessageHandler;
+import org.springframework.integration.support.MessageBuilder;
 import org.springframework.kafka.core.ConsumerFactory;
 import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.kafka.listener.ConsumerProperties;
+import org.springframework.kafka.support.KafkaHeaders;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.MessageHandler;
+import org.springframework.messaging.MessageHeaders;
+import org.springframework.messaging.support.ChannelInterceptor;
 
 
 @SpringBootApplication
@@ -21,6 +28,27 @@ import org.springframework.messaging.MessageHandler;
 @EnableIntegration
 public class SplitterApplication
 {
+	@Bean
+	MessageChannel words()
+	{
+		DirectChannel words = new DirectChannel();
+		words.addInterceptor(new ChannelInterceptor()
+		{
+			@Override
+			public Message<?> preSend(Message<?> message, MessageChannel channel)
+			{
+				MessageHeaders headers = message.getHeaders();
+				Object key = headers.get(KafkaHeaders.RECEIVED_MESSAGE_KEY);
+				return
+						MessageBuilder
+								.fromMessage(message)
+								.setHeader(KafkaHeaders.MESSAGE_KEY, key)
+								.build();
+			}
+		});
+		return words;
+	}
+
 	@InboundChannelAdapter(channel = "recordings")
 	@Bean
 	KafkaMessageSource<String, String> source(
-- 
2.20.1