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 (file)
--- 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 (file)
--- 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 (file)
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 (file)
--- 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