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import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.serialization.StringDeserializer;
import java.time.Duration;
import java.util.Collections;
import java.util.Properties;
public class JavaKafkaConsumer {
public static void main(String[] args) {
if (args.length < 2) {
System.err.println("Usage: java JavaKafkaConsumer <broker> <topic>");
System.exit(1);
}
String broker = args[0];
String topic = args[1];
System.out.println("Connecting to Kafka broker: " + broker);
System.out.println("Topic: " + topic);
Properties props = new Properties();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, broker);
props.put(ConsumerConfig.GROUP_ID_CONFIG, "java-test-group");
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "true");
props.put(ConsumerConfig.MAX_POLL_RECORDS_CONFIG, "10");
props.put(ConsumerConfig.FETCH_MIN_BYTES_CONFIG, "1");
props.put(ConsumerConfig.FETCH_MAX_WAIT_MS_CONFIG, "1000");
KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
consumer.subscribe(Collections.singletonList(topic));
System.out.println("Starting to consume messages...");
int messageCount = 0;
int errorCount = 0;
long startTime = System.currentTimeMillis();
try {
while (true) {
try {
ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(1000));
for (ConsumerRecord<String, String> record : records) {
messageCount++;
System.out.printf("Message #%d: topic=%s partition=%d offset=%d key=%s value=%s%n",
messageCount, record.topic(), record.partition(), record.offset(),
record.key(), record.value());
}
// Stop after 100 messages or 60 seconds
if (messageCount >= 100 || (System.currentTimeMillis() - startTime) > 60000) {
long duration = System.currentTimeMillis() - startTime;
System.out.printf("%nSuccessfully consumed %d messages in %dms%n", messageCount, duration);
System.out.printf("Success rate: %.1f%% (%d/%d including errors)%n",
(double) messageCount / (messageCount + errorCount) * 100, messageCount,
messageCount + errorCount);
break;
}
} catch (Exception e) {
errorCount++;
System.err.printf("Error during poll #%d: %s%n", errorCount, e.getMessage());
e.printStackTrace();
// Stop after 10 consecutive errors or 60 seconds
if (errorCount > 10 || (System.currentTimeMillis() - startTime) > 60000) {
long duration = System.currentTimeMillis() - startTime;
System.err.printf("%nStopping after %d errors in %dms%n", errorCount, duration);
break;
}
}
}
} finally {
consumer.close();
}
}
}
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