From: Kai Moritz <kai@juplo.de>
Date: Mon, 11 Nov 2024 20:24:25 +0000 (+0100)
Subject: Version des `spring-consumer`, der JSON-Nachrichten erwartet
X-Git-Tag: consumer/spring-consumer--json--2024-11-13--si
X-Git-Url: http://juplo.de/gitweb/?a=commitdiff_plain;h=refs%2Fheads%2Fconsumer%2Fspring-consumer--json;p=demos%2Fkafka%2Ftraining

Version des `spring-consumer`, der JSON-Nachrichten erwartet
---

diff --git a/README.sh b/README.sh
index b46e235..7152ec9 100755
--- a/README.sh
+++ b/README.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-IMAGE=juplo/spring-consumer:1.1-SNAPSHOT
+IMAGE=juplo/spring-consumer:1.1-json-SNAPSHOT
 
 if [ "$1" = "cleanup" ]
 then
diff --git a/docker/docker-compose.yml b/docker/docker-compose.yml
index 6bd2766..2e40b79 100644
--- a/docker/docker-compose.yml
+++ b/docker/docker-compose.yml
@@ -190,7 +190,7 @@ services:
       - kafka-3
 
   producer:
-    image: juplo/spring-producer:1.0-SNAPSHOT
+    image: juplo/spring-producer:1.0-json-SNAPSHOT
     environment:
       juplo.bootstrap-server: kafka:9092
       juplo.client-id: producer
@@ -199,7 +199,7 @@ services:
       juplo.producer.throttle-ms: 100
 
   consumer:
-    image: juplo/spring-consumer:1.1-SNAPSHOT
+    image: juplo/spring-consumer:1.1-json-SNAPSHOT
     environment:
       juplo.bootstrap-server: kafka:9092
       juplo.client-id: consumer
diff --git a/pom.xml b/pom.xml
index 98a0a36..30cda01 100644
--- a/pom.xml
+++ b/pom.xml
@@ -15,7 +15,7 @@
   <artifactId>spring-consumer</artifactId>
   <name>Spring Consumer</name>
   <description>Super Simple Consumer-Group, that is implemented as Spring-Boot application and configured by Spring Kafka</description>
-  <version>1.1-SNAPSHOT</version>
+  <version>1.1-json-SNAPSHOT</version>
 
   <properties>
     <java.version>21</java.version>
@@ -40,8 +40,8 @@
       <artifactId>spring-boot-starter-validation</artifactId>
     </dependency>
     <dependency>
-      <groupId>org.apache.kafka</groupId>
-      <artifactId>kafka-clients</artifactId>
+      <groupId>org.springframework.kafka</groupId>
+      <artifactId>spring-kafka</artifactId>
     </dependency>
     <dependency>
       <groupId>org.projectlombok</groupId>
@@ -52,11 +52,6 @@
       <artifactId>spring-boot-starter-test</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.springframework.kafka</groupId>
-      <artifactId>spring-kafka</artifactId>
-      <scope>test</scope>
-    </dependency>
     <dependency>
       <groupId>org.springframework.kafka</groupId>
       <artifactId>spring-kafka-test</artifactId>
diff --git a/src/main/java/de/juplo/kafka/ApplicationConfiguration.java b/src/main/java/de/juplo/kafka/ApplicationConfiguration.java
index a4856a6..3f7422c 100644
--- a/src/main/java/de/juplo/kafka/ApplicationConfiguration.java
+++ b/src/main/java/de/juplo/kafka/ApplicationConfiguration.java
@@ -4,6 +4,7 @@ import org.apache.kafka.clients.consumer.Consumer;
 import org.apache.kafka.clients.consumer.KafkaConsumer;
 import org.apache.kafka.clients.consumer.StickyAssignor;
 import org.apache.kafka.common.serialization.StringDeserializer;
+import org.springframework.kafka.support.serializer.JsonDeserializer;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -18,7 +19,7 @@ public class ApplicationConfiguration
 {
   @Bean
   public ExampleConsumer exampleConsumer(
-      Consumer<String, String> kafkaConsumer,
+      Consumer<String, Message> kafkaConsumer,
       ApplicationProperties properties,
       ConfigurableApplicationContext applicationContext)
   {
@@ -31,7 +32,7 @@ public class ApplicationConfiguration
   }
 
   @Bean(destroyMethod = "")
-  public KafkaConsumer<String, String> kafkaConsumer(ApplicationProperties properties)
+  public KafkaConsumer<String, Message> kafkaConsumer(ApplicationProperties properties)
   {
     Properties props = new Properties();
     props.put("bootstrap.servers", properties.getBootstrapServer());
@@ -48,7 +49,8 @@ public class ApplicationConfiguration
     props.put("metadata.maxage.ms", 5000); //  5 Sekunden
     props.put("partition.assignment.strategy", StickyAssignor.class.getName());
     props.put("key.deserializer", StringDeserializer.class.getName());
-    props.put("value.deserializer", StringDeserializer.class.getName());
+    props.put("value.deserializer", JsonDeserializer.class.getName());
+    props.put("spring.json.type.mapping", "ADD:de.juplo.kafka.MessageAddNumber,CALC:de.juplo.kafka.MessageCalculateSum");
 
     return new KafkaConsumer<>(props);
   }
diff --git a/src/main/java/de/juplo/kafka/ExampleConsumer.java b/src/main/java/de/juplo/kafka/ExampleConsumer.java
index f832b45..654ef37 100644
--- a/src/main/java/de/juplo/kafka/ExampleConsumer.java
+++ b/src/main/java/de/juplo/kafka/ExampleConsumer.java
@@ -15,7 +15,7 @@ public class ExampleConsumer implements Runnable
 {
   private final String id;
   private final String topic;
-  private final Consumer<String, String> consumer;
+  private final Consumer<String, Message> consumer;
   private final Thread workerThread;
   private final Runnable closeCallback;
 
@@ -26,7 +26,7 @@ public class ExampleConsumer implements Runnable
   public ExampleConsumer(
     String clientId,
     String topic,
-    Consumer<String, String> consumer,
+    Consumer<String, Message> consumer,
     Runnable closeCallback)
   {
     this.id = clientId;
@@ -51,11 +51,11 @@ public class ExampleConsumer implements Runnable
 
       while (running)
       {
-        ConsumerRecords<String, String> records =
+        ConsumerRecords<String, Message> records =
             consumer.poll(Duration.ofSeconds(1));
 
         log.info("{} - Received {} messages", id, records.count());
-        for (ConsumerRecord<String, String> record : records)
+        for (ConsumerRecord<String, Message> record : records)
         {
           handleRecord(
             record.topic(),
@@ -90,7 +90,7 @@ public class ExampleConsumer implements Runnable
     Integer partition,
     Long offset,
     String key,
-    String value)
+    Message value)
   {
     consumed++;
     log.info("{} - {}: {}/{} - {}={}", id, offset, topic, partition, key, value);
diff --git a/src/main/java/de/juplo/kafka/Message.java b/src/main/java/de/juplo/kafka/Message.java
new file mode 100644
index 0000000..e4999b7
--- /dev/null
+++ b/src/main/java/de/juplo/kafka/Message.java
@@ -0,0 +1,9 @@
+package de.juplo.kafka;
+
+
+public abstract class Message
+{
+  public enum Type {ADD, CALC}
+
+  public abstract Type getType();
+}
diff --git a/src/main/java/de/juplo/kafka/MessageAddNumber.java b/src/main/java/de/juplo/kafka/MessageAddNumber.java
new file mode 100644
index 0000000..c024b65
--- /dev/null
+++ b/src/main/java/de/juplo/kafka/MessageAddNumber.java
@@ -0,0 +1,19 @@
+package de.juplo.kafka;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import lombok.Data;
+
+
+@Data
+@JsonIgnoreProperties(ignoreUnknown = true)
+public class MessageAddNumber extends Message
+{
+  private Integer next;
+
+
+  @Override
+  public Type getType()
+  {
+    return Type.ADD;
+  }
+}
diff --git a/src/main/java/de/juplo/kafka/MessageCalculateSum.java b/src/main/java/de/juplo/kafka/MessageCalculateSum.java
new file mode 100644
index 0000000..afc5a39
--- /dev/null
+++ b/src/main/java/de/juplo/kafka/MessageCalculateSum.java
@@ -0,0 +1,16 @@
+package de.juplo.kafka;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import lombok.Data;
+
+
+@Data
+@JsonIgnoreProperties(ignoreUnknown = true)
+public class MessageCalculateSum extends Message
+{
+  @Override
+  public Type getType()
+  {
+    return Type.CALC;
+  }
+}
diff --git a/src/test/java/de/juplo/kafka/MessageTest.java b/src/test/java/de/juplo/kafka/MessageTest.java
new file mode 100644
index 0000000..82116f4
--- /dev/null
+++ b/src/test/java/de/juplo/kafka/MessageTest.java
@@ -0,0 +1,29 @@
+package de.juplo.kafka;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+
+public class MessageTest
+{
+  ObjectMapper mapper = new ObjectMapper();
+
+  @Test
+  @DisplayName("Deserialize a MessageAddNumber message")
+  public void testDeserializeMessageAddNumber()
+  {
+    Assertions.assertDoesNotThrow(() -> mapper.readValue("{\"next\":42}", MessageAddNumber.class));
+    Assertions.assertDoesNotThrow(() -> mapper.readValue("{\"number\":666,\"next\":42}", MessageAddNumber.class));
+  }
+
+  @Test
+  @DisplayName("Deserialize a MessageCalculateSum message")
+  public void testDeserializeMessageCalculateSum() throws JsonProcessingException
+  {
+    Assertions.assertDoesNotThrow(() -> mapper.readValue("{}", MessageCalculateSum.class));
+    Assertions.assertDoesNotThrow(() -> mapper.readValue("{\"number\":666}", MessageCalculateSum.class));
+  }
+}