From: Kai Moritz <kai@juplo.de>
Date: Sun, 17 Apr 2022 11:33:40 +0000 (+0200)
Subject: Springify: Der Payload ist eine als JSON gerenderte Klasse
X-Git-Tag: sumup-adder---lvm-2-tage~9^2~7^2~7
X-Git-Url: http://juplo.de/gitweb/?a=commitdiff_plain;h=a14a1d5222b18506311cb8fe7c59dfe0f5458cf3;p=demos%2Fkafka%2Ftraining

Springify: Der Payload ist eine als JSON gerenderte Klasse

* Als Nachricht wird eine Instanz der Klasse `ClientMessage` erwartet
* Die Instanz wird mit Hilfe des `JsonDeserializer` von Spring Kafka
  deserialisiert.
---

diff --git a/pom.xml b/pom.xml
index f218085..21466ec 100644
--- a/pom.xml
+++ b/pom.xml
@@ -38,6 +38,10 @@
       <groupId>org.apache.kafka</groupId>
       <artifactId>kafka-clients</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.springframework.kafka</groupId>
+      <artifactId>spring-kafka</artifactId>
+    </dependency>
     <dependency>
       <groupId>org.projectlombok</groupId>
       <artifactId>lombok</artifactId>
diff --git a/src/main/java/de/juplo/kafka/ApplicationConfiguration.java b/src/main/java/de/juplo/kafka/ApplicationConfiguration.java
index 4054e93..566c7a3 100644
--- a/src/main/java/de/juplo/kafka/ApplicationConfiguration.java
+++ b/src/main/java/de/juplo/kafka/ApplicationConfiguration.java
@@ -7,6 +7,7 @@ import org.apache.kafka.common.serialization.StringDeserializer;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.kafka.support.serializer.JsonDeserializer;
 
 import java.util.Properties;
 import java.util.concurrent.ExecutorService;
@@ -19,7 +20,7 @@ import java.util.function.Consumer;
 public class ApplicationConfiguration
 {
   @Bean
-  public Consumer<ConsumerRecord<String, Long>> consumer()
+  public Consumer<ConsumerRecord<String, ClientMessage>> consumer()
   {
     return (record) ->
     {
@@ -28,10 +29,10 @@ public class ApplicationConfiguration
   }
 
   @Bean
-  public EndlessConsumer<String, Long> endlessConsumer(
-      KafkaConsumer<String, Long> kafkaConsumer,
+  public EndlessConsumer<String, ClientMessage> endlessConsumer(
+      KafkaConsumer<String, ClientMessage> kafkaConsumer,
       ExecutorService executor,
-      Consumer<ConsumerRecord<String, Long>> handler,
+      Consumer<ConsumerRecord<String, ClientMessage>> handler,
       ApplicationProperties properties)
   {
     return
@@ -50,7 +51,7 @@ public class ApplicationConfiguration
   }
 
   @Bean(destroyMethod = "close")
-  public KafkaConsumer<String, Long> kafkaConsumer(ApplicationProperties properties)
+  public KafkaConsumer<String, ClientMessage> kafkaConsumer(ApplicationProperties properties)
   {
     Properties props = new Properties();
 
@@ -60,7 +61,9 @@ public class ApplicationConfiguration
     props.put("auto.offset.reset", properties.getAutoOffsetReset());
     props.put("metadata.max.age.ms", "1000");
     props.put("key.deserializer", StringDeserializer.class.getName());
-    props.put("value.deserializer", LongDeserializer.class.getName());
+    props.put("value.deserializer", JsonDeserializer.class.getName());
+    props.put(JsonDeserializer.VALUE_DEFAULT_TYPE, ClientMessage.class.getName());
+    props.put(JsonDeserializer.TRUSTED_PACKAGES, "de.juplo.kafka");
 
     return new KafkaConsumer<>(props);
   }
diff --git a/src/main/java/de/juplo/kafka/ClientMessage.java b/src/main/java/de/juplo/kafka/ClientMessage.java
new file mode 100644
index 0000000..d18800b
--- /dev/null
+++ b/src/main/java/de/juplo/kafka/ClientMessage.java
@@ -0,0 +1,11 @@
+package de.juplo.kafka;
+
+import lombok.Data;
+
+
+@Data
+public class ClientMessage
+{
+  String client;
+  String message;
+}
diff --git a/src/test/java/de/juplo/kafka/ApplicationTests.java b/src/test/java/de/juplo/kafka/ApplicationTests.java
index 40dc149..fbc668f 100644
--- a/src/test/java/de/juplo/kafka/ApplicationTests.java
+++ b/src/test/java/de/juplo/kafka/ApplicationTests.java
@@ -15,6 +15,7 @@ import org.springframework.boot.test.context.ConfigDataApplicationContextInitial
 import org.springframework.boot.test.context.TestConfiguration;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Import;
+import org.springframework.kafka.support.serializer.JsonSerializer;
 import org.springframework.kafka.test.context.EmbeddedKafka;
 import org.springframework.test.context.TestPropertySource;
 import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
@@ -24,8 +25,8 @@ import java.util.*;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.function.BiConsumer;
+import java.util.function.BiFunction;
 import java.util.function.Consumer;
-import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
@@ -56,7 +57,7 @@ class ApplicationTests
 	@Autowired
 	KafkaProducer<String, Bytes> kafkaProducer;
 	@Autowired
-	KafkaConsumer<String, Long> kafkaConsumer;
+	KafkaConsumer<String, ClientMessage> kafkaConsumer;
 	@Autowired
 	KafkaConsumer<Bytes, Bytes> offsetConsumer;
 	@Autowired
@@ -64,11 +65,11 @@ class ApplicationTests
 	@Autowired
 	ExecutorService executor;
 
-	Consumer<ConsumerRecord<String, Long>> testHandler;
-	EndlessConsumer<String, Long> endlessConsumer;
+	Consumer<ConsumerRecord<String, ClientMessage>> testHandler;
+	EndlessConsumer<String, ClientMessage> endlessConsumer;
 	Map<TopicPartition, Long> oldOffsets;
 	Map<TopicPartition, Long> newOffsets;
-	Set<ConsumerRecord<String, Long>> receivedRecords;
+	Set<ConsumerRecord<String, ClientMessage>> receivedRecords;
 
 
 	/** Tests methods */
@@ -77,7 +78,7 @@ class ApplicationTests
 	@Order(1) // << The poistion pill is not skipped. Hence, this test must run first
 	void commitsCurrentOffsetsOnSuccess() throws ExecutionException, InterruptedException
 	{
-		send100Messages(i ->  new Bytes(valueSerializer.serialize(TOPIC, i)));
+		send100Messages((key, counter) -> serialize(key, counter));
 
 		await("100 records received")
 				.atMost(Duration.ofSeconds(30))
@@ -100,10 +101,10 @@ class ApplicationTests
 	@Order(2)
 	void commitsOffsetOfErrorForReprocessingOnError()
 	{
-		send100Messages(counter ->
+		send100Messages((key, counter) ->
 				counter == 77
 						? new Bytes(stringSerializer.serialize(TOPIC, "BOOM!"))
-						: new Bytes(valueSerializer.serialize(TOPIC, counter)));
+						: serialize(key, counter));
 
 		await("Consumer failed")
 				.atMost(Duration.ofSeconds(30))
@@ -185,7 +186,7 @@ class ApplicationTests
 	}
 
 
-	void send100Messages(Function<Long, Bytes> messageGenerator)
+	void send100Messages(BiFunction<Integer, Long, Bytes> messageGenerator)
 	{
 		long i = 0;
 
@@ -193,7 +194,7 @@ class ApplicationTests
 		{
 			for (int key = 0; key < 10; key++)
 			{
-				Bytes value = messageGenerator.apply(++i);
+				Bytes value = messageGenerator.apply(key, ++i);
 
 				ProducerRecord<String, Bytes> record =
 						new ProducerRecord<>(
@@ -226,6 +227,14 @@ class ApplicationTests
 		}
 	}
 
+	Bytes serialize(Integer key, Long value)
+	{
+		ClientMessage message = new ClientMessage();
+		message.setClient(key.toString());
+		message.setMessage(value.toString());
+		return new Bytes(valueSerializer.serialize(TOPIC, message));
+	}
+
 
 	@BeforeEach
 	public void init()
@@ -242,7 +251,7 @@ class ApplicationTests
 			newOffsets.put(tp, offset - 1);
 		});
 
-		Consumer<ConsumerRecord<String, Long>> captureOffsetAndExecuteTestHandler =
+		Consumer<ConsumerRecord<String, ClientMessage>> captureOffsetAndExecuteTestHandler =
 				record ->
 				{
 					newOffsets.put(
@@ -282,9 +291,9 @@ class ApplicationTests
 	public static class Configuration
 	{
 		@Bean
-		Serializer<Long> serializer()
+		Serializer<ClientMessage> serializer()
 		{
-			return new LongSerializer();
+			return new JsonSerializer<>();
 		}
 
 		@Bean