RocketMQ消费者示例程序

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　　本博客实现了一个简单的RocketMQ消费者的示例,MQ里存储的是经过Avro序列化的消息数据，程序读取数据并反序列化后，将消息从控制台打印出来。

　　程序通过stdin.xml配置文件获取主要参数值，stdin.xml文件内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<operator>
    <parameters>
        <parameter>
            <key>rocketmq.nameserver.list</key>
            <value>172.16.8.106:9876</value>
        </parameter>
        <parameter>
            <key>rocketmq.group.id</key>
            <value>test006</value>
        </parameter>
        <parameter>
            <key>rocketmq.topic</key>
            <value>TopicTest2</value>
        </parameter>
        <parameter>
            <key>rocketmq.tags</key>
            <value>*</value>
        </parameter>
        <parameter>
            <key>rocketmq.message.key</key>
            <value>OrderID0034</value>
        </parameter>
        <parameter>
            <key>schemaStr</key>
            <value>col1:string,col2:double</value>
        </parameter>
        <parameter>
            <key>filePath</key>
            <value>/home/test/rocketmq/input.txt</value>
        </parameter>
    </parameters>
</operator>

消费者示例程序如下：

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import com.alibaba.rocketmq.client.consumer.DefaultMQPushConsumer;
import com.alibaba.rocketmq.client.consumer.listener.ConsumeConcurrentlyContext;
import com.alibaba.rocketmq.client.consumer.listener.ConsumeConcurrentlyStatus;
import com.alibaba.rocketmq.client.consumer.listener.MessageListenerConcurrently;
import com.alibaba.rocketmq.client.exception.MQClientException;
import com.alibaba.rocketmq.common.message.MessageExt;
import com.scistor.datavision.operator.common.OperatorConfiguration;
import org.apache.avro.Schema;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.Decoder;
import org.apache.avro.io.DecoderFactory;
import org.apache.hive.hcatalog.common.HCatException;
import org.apache.hive.hcatalog.data.schema.HCatSchema;
 
import java.io.IOException;
import java.util.List;
 
 
public class RocketConsumer {
    private static Schema schema = null;
    // parameters
    private String nameserver;
    private String groupID;
    private String rocketmqTopic;
    private String tags;
    private String schemaStr;
 
    public RocketConsumer configure(OperatorConfiguration conf) {
        this.nameserver = conf.get("rocketmq.nameserver.list");
        this.groupID = conf.get("rocketmq.group.id");
        this.rocketmqTopic = conf.get("rocketmq.topic");
        this.tags = conf.get("rocketmq.tags");
        this.schemaStr = conf.get("schemaStr");
        return this;
    }
 
    /**
     * 当前例子是PushConsumer用法，使用方式给用户感觉是消息从RocketMQ服务器推到了应用客户端。<br>
     * 但是实际PushConsumer内部是使用长轮询Pull方式从MetaQ服务器拉消息，然后再回调用户Listener方法<br>
     */
    public void run() throws MQClientException {
        /**
         * 一个应用创建一个Consumer，由应用来维护此对象，可以设置为全局对象或者单例<br>
         * 注意：ConsumerGroupName需要由应用来保证唯一
         */
        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("ConsumerGroupName");
        consumer.setNamesrvAddr(nameserver);
        consumer.setInstanceName(groupID+"Consumber");
        consumer.setConsumerGroup(groupID);
 
        try {
            consumer.subscribe(rocketmqTopic, tags);
        } catch (MQClientException e) {
            e.printStackTrace();
        }
 
        HCatSchema hcatSchema = null;
        SchemaUtil schemaUtil = new SchemaUtil();
        try {
            hcatSchema = schemaUtil.createHCatSchema(schemaStr);
            schema = schemaUtil.createSchema("com.scistor.rocketmq.producer", rocketmqTopic, hcatSchema);
        } catch (HCatException e) {
            e.printStackTrace();
        }
 
        consumer.registerMessageListener(new MessageListenerConcurrently() {
            /**
             * 默认msgs里只有一条消息，可以通过设置consumeMessageBatchMaxSize参数来批量接收消息
             */
            public ConsumeConcurrentlyStatus consumeMessage(
                    List<MessageExt> msgs, ConsumeConcurrentlyContext context) {
                System.out.println(Thread.currentThread().getName()
                        + " Receive New Messages: " + msgs.size());
 
                for (MessageExt msg : msgs) {
                    if (msg.getTopic().equals(rocketmqTopic)) {
                        byte[] bytes = msg.getBody();
                        DatumReader<GenericRecord> reader = new GenericDatumReader<GenericRecord>(schema);
                        Decoder decoder = DecoderFactory.get().binaryDecoder(bytes, null);
                        GenericRecord record1 = null;
                        try {
                            record1 = reader.read(null, decoder);
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                        int fieldSize = record1.getSchema().getFields().size();
                        for (int i = 0; i < fieldSize; i++) {
                            System.out.print(record1.get(i) + "====");
                        }
                        System.out.println();
                    }
                }
                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
            }
        });
 
        /**
         * Consumer对象在使用之前必须要调用start初始化，初始化一次即可<br>
         */
        consumer.start();
 
        System.out.println("Consumer Started.");
    }
 
    public static void main(String[] args) throws MQClientException {
        if (args.length < 1) {
            System.err.println("需要： 参数配置文件<stdin.xml>所在的hdfs目录");
            System.exit(-1);
        }
        OperatorConfiguration conf = new OperatorConfiguration(args[0]);
        RocketConsumer trainer = new RocketConsumer();
        trainer.configure(conf).run();
    }
}

程序运行输出打印到控制台：

[root@m106 rocketmq]# ./consumer.sh 
Consumer Started.
ConsumeMessageThread_5 Receive New Messages: 1
ConsumeMessageThread_1 Receive New Messages: 1
ConsumeMessageThread_9 Receive New Messages: 1
ConsumeMessageThread_8 Receive New Messages: 1
ConsumeMessageThread_7 Receive New Messages: 1
ConsumeMessageThread_4 Receive New Messages: 1
ConsumeMessageThread_2 Receive New Messages: 1
ConsumeMessageThread_10 Receive New Messages: 1
ConsumeMessageThread_3 Receive New Messages: 1
ConsumeMessageThread_6 Receive New Messages: 1
/home/xdf/workflow/file-web/file/1.html====hdfs:///user/xdf/streaming/file-web/file/3.html====1.0====hdfs:///user/xdf/streaming/file-web/file/2.html====hdfs:///user/xdf/streaming/file-web/file/4.html====/home/xdf/workflow/file-web/file/3.html====hdfs:///user/xdf/streaming/file-web/file/1.html====/home/xdf/workflow/file-web/file====1.0====
hdfs:///user/xdf/streaming/file-web/file====/home/xdf/workflow/file-web/file/2.html====/home/xdf/workflow/file-web/file/4.html====2.0====
1.0====
1.0====
3.0====
4.0====
2.0====
3.0====
4.0====