ApsaraMQ for Kafka：Send and receive messages by using the default endpoint

The following sample code provides an example on how to compile and run KafkaProducerDemo.java to send messages:

import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.Future;
// If you use an SSL endpoint or SASL endpoint to access the ApsaraMQ for Kafka instance, comment out the first line of the following code: 
import java.util.concurrent.TimeUnit;
import org.apache.kafka.clients.CommonClientConfigs;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;
/*
*If you use an SSL endpoint or SASL endpoint to access the ApsaraMQ for Kafka instance, uncomment the following two lines of code: 
import org.apache.kafka.common.config.SaslConfigs;
import org.apache.kafka.common.config.SslConfigs;
*/

public class KafkaProducerDemo {

    public static void main(String args[]) {
          
       /*
        * If you use an SSL endpoint to access the ApsaraMQ for Kafka instance, uncomment the following line of code: 
        Specify the path of the JAAS configuration file. 
        JavaKafkaConfigurer.configureSasl();
        */
         
       /*
        * If you use an SASL endpoint that uses the PLAIN mechanism to access the ApsaraMQ for Kafka instance, uncomment the following line of code: 
        Specify the path of the JAAS configuration file. 
        JavaKafkaConfigurer.configureSaslPlain();
        */
       
       /*
        * If you use an SASL endpoint that uses the SCRAM mechanism to access the ApsaraMQ for Kafka instance, uncomment the following line of code: 
        Specify the path of the JAAS configuration file. 
        JavaKafkaConfigurer.configureSaslScram();
        */

        // Load the kafka.properties file. 
        Properties kafkaProperties =  JavaKafkaConfigurer.getKafkaProperties();

        Properties props = new Properties();
        // Specify the endpoint. You can obtain the endpoint of the topic on the Instance Details page in the ApsaraMQ for Kafka console. 
        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaProperties.getProperty("bootstrap.servers"));
         
       /*
        * If you use an SSL endpoint to access the ApsaraMQ for Kafka instance, uncomment the following four lines of code: 
        * Do not compress the file into a JAR package. 
        props.put(SslConfigs.SSL_TRUSTSTORE_LOCATION_CONFIG, kafkaProperties.getProperty("ssl.truststore.location"));
        * The password of the truststore in the root certificate. Use the default value. 
        props.put(SslConfigs.SSL_TRUSTSTORE_PASSWORD_CONFIG, "KafkaOnsClient");
        * The access protocol. Set this parameter to SASL_SSL. 
        props.put(CommonClientConfigs.SECURITY_PROTOCOL_CONFIG, "SASL_SSL");
        * The SASL authentication method. Use the default value. 
        props.put(SaslConfigs.SASL_MECHANISM, "PLAIN");
        */

       /*
        * If you use an SASL endpoint that uses the PLAIN mechanism to access the ApsaraMQ for Kafka instance, uncomment the following two lines of code: 
        * The access protocol. 
        props.put(CommonClientConfigs.SECURITY_PROTOCOL_CONFIG, "SASL_PLAINTEXT");
        * The PLAIN mechanism. 
        props.put(SaslConfigs.SASL_MECHANISM, "PLAIN");
        */

       /*
        * If you use an SASL endpoint that uses the SCRAM mechanism to access the ApsaraMQ for Kafka instance, uncomment the following two lines of code: 
        * The access protocol. 
        props.put(CommonClientConfigs.SECURITY_PROTOCOL_CONFIG, "SASL_PLAINTEXT");
        * The SCRAM mechanism. 
        props.put(SaslConfigs.SASL_MECHANISM, "SCRAM-SHA-256");
        */

        // The method that is used to serialize messages in ApsaraMQ for Kafka. 
        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
        // The maximum waiting time for a request. 
        props.put(ProducerConfig.MAX_BLOCK_MS_CONFIG, 30 * 1000);
        // Specify the maximum number of retries for the messages in the client. 
        props.put(ProducerConfig.RETRIES_CONFIG, 5);
        // Specify the interval between two consecutive retries for the messages in the client. 
        props.put(ProducerConfig.RETRY_BACKOFF_MS_CONFIG, 3000);
         
       /*
        * If you use an SSL endpoint to access the ApsaraMQ for Kafka instance, uncomment the following line of code: 
        * Set the algorithm for hostname verification to an empty value. 
        props.put(SslConfigs.SSL_ENDPOINT_IDENTIFICATION_ALGORITHM_CONFIG, "");
        */

        // Construct a thread-safe producer object. Construct one producer object for a process. 
        // To improve performance, you can construct multiple producer objects. We recommend that you construct no more than five producer objects. 
        KafkaProducer<String, String> producer = new KafkaProducer<String, String>(props);

        // Construct an ApsaraMQ for Kafka message. 
        String topic = kafkaProperties.getProperty("topic"); // The topic to which the message belongs. Enter the topic that you created in the ApsaraMQ for Kafka console. 
        String value = "this is the message's value"; // The content of the message. 

        try {
            // Obtaining multiple future objects at a time can help improve efficiency. However, do not obtain a large number of future objects at a time. 
            List<Future<RecordMetadata>> futures = new ArrayList<Future<RecordMetadata>>(128);
            for (int i =0; i < 100; i++) {
                // Send the message and obtain a future object. 
                ProducerRecord<String, String> kafkaMessage =  new ProducerRecord<String, String>(topic, value + ": " + i);
                Future<RecordMetadata> metadataFuture = producer.send(kafkaMessage);
                futures.add(metadataFuture);

            }
            producer.flush();
            for (Future<RecordMetadata> future: futures) {
                // Obtain the results of the future object in a synchronous manner. 
                try {
                    RecordMetadata recordMetadata = future.get();
                    System.out.println("Produce ok:" + recordMetadata.toString());
                } catch (Throwable t) {
                    t.printStackTrace();
                }
            }
        } catch (Exception e) {
            // If the message still fails to be sent after retries, troubleshoot the error. 
            System.out.println("error occurred");
            e.printStackTrace();
        }
    }
}