1 files changed, 59 insertions, 12 deletions

diff --git a/kafka-sandbox/src/main/java/examples/ConsumerExample.java b/kafka-sandbox/src/main/java/examples/ConsumerExample.java
index e491035..6672166 100644
--- a/kafka-sandbox/src/main/java/examples/ConsumerExample.java
+++ b/kafka-sandbox/src/main/java/examples/ConsumerExample.java
@@ -1,38 +1,85 @@
 package examples;
 
-import org.apache.kafka.clients.consumer.*;
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRebalanceListener;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.TopicPartition;
 
 import java.time.Duration;
-import java.util.Arrays;
-import java.util.Properties;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
 
 public class ConsumerExample {
+    private static final Map<String, String> mappings = new TreeMap<>();
+
     public static void main(final String[] args) throws Exception {
         if (args.length != 1) {
             System.out.println("Please provide the configuration file path as a command line argument");
             System.exit(1);
         }
 
-        final String topic = "purchases";
+        var topic = "purchases";
 
         // Load consumer configuration settings from a local file
         // Reusing the loadConfig method from the ProducerExample class
-        final Properties props = ProducerExample.loadConfig(args[0]);
+        var props = ProducerExample.loadConfig(args[0]);
 
         // Add additional properties.
         props.put(ConsumerConfig.GROUP_ID_CONFIG, "kafka-java-getting-started");
         props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
 
-        try (final Consumer<String, String> consumer = new KafkaConsumer<>(props)) {
-            consumer.subscribe(Arrays.asList(topic));
+        var first = true;
+
+        try (var consumer = new KafkaConsumer<String, String>(props)) {
+            consumer.subscribe(List.of(topic), new ConsumerRebalanceListener() {
+                @Override
+                public void onPartitionsRevoked(Collection<TopicPartition> partitions) {
+                    System.out.println("ConsumerExample.onPartitionsRevoked");
+                    partitions.forEach(p -> System.out.println("p = " + p));
+                }
+
+                @Override
+                public void onPartitionsAssigned(Collection<TopicPartition> partitions) {
+                    System.out.println("ConsumerExample.onPartitionsAssigned");
+                    partitions.forEach(p -> System.out.println("p = " + p));
+                    consumer.seekToBeginning(partitions);
+                }
+            });
             while (true) {
-                ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
-                for (ConsumerRecord<String, String> record : records) {
-                    String key = record.key();
-                    String value = record.value();
-                    System.out.println(String.format("Consumed event from topic %s: key = %-10s value = %s", topic, key, value));
+                var records = consumer.poll(Duration.ofMillis(1000));
+                for (var record : records) {
+                    var username = record.key();
+                    var email = record.value();
+                    if (!first) {
+                        System.out.printf("Consumed event from topic %s: username = %-10s email = %s%n", topic, username, email);
+                    }
+
+                    if (email == null) {
+                        mappings.remove(username);
+                    } else {
+                        mappings.put(username, email);
+                    }
                 }
+
+                if (!records.isEmpty()) {
+                    if (first) {
+                        System.out.println("FIRST");
+                    }
+                    System.out.println("Got " + records.count() + " records!");
+                    showMappings();
+                }
+
+                first = false;
             }
         }
     }
+
+    private static void showMappings() {
+        System.out.println("----------");
+        for (var mapping : mappings.entrySet()) {
+            System.out.printf("%-10s = %s%n", mapping.getKey(), mapping.getValue());
+        }
+    }
 }