阿里IOT用AMQP在服務端訂閱消息，踩坑

之前一直按官方文檔來的，但是topic消息一直積壓，服務端老是訂閱不到。

坑： 

String iotInstanceId = "${iotInstanceId}";

這個參數是要填實例ID，文檔說：“沒有購買實例可忽略”。然後我就保持沒動。結果訂閱不到。

改：

String iotInstanceId = "";

 附代碼：

package amqp;

import java.net.URI;
import java.util.Hashtable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.naming.Context;
import javax.naming.InitialContext;
import org.apache.commons.codec.binary.Base64;
import org.apache.qpid.jms.JmsConnection;
import org.apache.qpid.jms.JmsConnectionListener;
import org.apache.qpid.jms.message.JmsInboundMessageDispatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

class AmqpJavaClient {

    private final static Logger logger = LoggerFactory.getLogger(AmqpJavaClient.class);

    //業務處理異步線程池，線程池參數可以根據您的業務特點調整；或者您也可以用其他異步方式處理接收到的消息
    private final static ExecutorService executorService = new ThreadPoolExecutor(
            Runtime.getRuntime().availableProcessors(),
            Runtime.getRuntime().availableProcessors() * 2, 60, TimeUnit.SECONDS,
            new LinkedBlockingQueue<>(50000));

    public static void main(String[] args) throws Exception {
        System.out.println("測試0");
        //參數說明，請參見上一篇文檔：AMQP客戶端接入說明。
        String accessKey = "LTAI4GCvKHPiaJUX7wmXPZYz";
        String accessSecret = "H5u7cJbFPsvioZhWe1fLc6R6BrYZ8U";
        String consumerGroupId = "DEFAULT_GROUP";
        String iotInstanceId = "";  //這裏如果沒有購買實例就別填，不然接收不到消息
        long timeStamp = System.currentTimeMillis();
        //簽名方法：支持hmacmd5，hmacsha1和hmacsha256
        String signMethod = "hmacsha1";
        //控制檯服務端訂閱中消費組狀態頁客戶端ID一欄將顯示clientId參數。
        //建議使用機器UUID、MAC地址、IP等唯一標識等作爲clientId。便於您區分識別不同的客戶端。
        String clientId = "XB001";

        //UserName組裝方法，請參見上一篇文檔：AMQP客戶端接入說明。
        String userName = clientId + "|authMode=aksign"
                + ",signMethod=" + signMethod
                + ",timestamp=" + timeStamp
                + ",authId=" + accessKey
                + ",iotInstanceId=" + iotInstanceId //如果是購買的實例，需要傳實例ID
                + ",consumerGroupId=" + consumerGroupId
                + "|";
        //password組裝方法，請參見上一篇文檔：AMQP客戶端接入說明。
        String signContent = "authId=" + accessKey + "&timestamp=" + timeStamp;
        String password = doSign(signContent,accessSecret, signMethod);
        //按照qpid-jms的規範，組裝連接URL。
        String connectionUrl = "failover:(amqps://1773647983940296.iot-amqp.cn-shanghai.aliyuncs.com:5671?amqp.idleTimeout=80000)"
                + "?failover.reconnectDelay=30";

        Hashtable<String, String> hashtable = new Hashtable<>();
        hashtable.put("connectionfactory.SBCF",connectionUrl);
        hashtable.put("queue.QUEUE", "default");
        hashtable.put(Context.INITIAL_CONTEXT_FACTORY, "org.apache.qpid.jms.jndi.JmsInitialContextFactory");
        Context context = new InitialContext(hashtable);
        ConnectionFactory cf = (ConnectionFactory)context.lookup("SBCF");
        Destination queue = (Destination)context.lookup("QUEUE");
        // Create Connection
        Connection connection = cf.createConnection(userName, password);
        ((JmsConnection) connection).addConnectionListener(myJmsConnectionListener);
        // Create Session
        // Session.CLIENT_ACKNOWLEDGE: 收到消息後，需要手動調用message.acknowledge()
        // Session.AUTO_ACKNOWLEDGE: SDK自動ACK（推薦）
        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        connection.start();
        // Create Receiver Link
        MessageConsumer consumer = session.createConsumer(queue);
        consumer.setMessageListener(messageListener);
        System.out.println("測試0.1");
    }

    private static MessageListener messageListener = new MessageListener() {
        @Override
        public void onMessage(Message message) {
            try {
                System.out.println("測試1");
                //1.收到消息之後一定要ACK
                // 推薦做法：創建Session選擇Session.AUTO_ACKNOWLEDGE，這裏會自動ACK。
                // 其他做法：創建Session選擇Session.CLIENT_ACKNOWLEDGE，這裏一定要調message.acknowledge()來ACK。
                //message.acknowledge();

                //2.建議異步處理收到的消息，確保onMessage函數裏沒有耗時邏輯。
                // 如果業務處理耗時過程過長阻塞住線程，可能會影響SDK收到消息後的正常回調。
                executorService.submit(() -> processMessage(message));
            } catch (Exception e) {
                System.out.println("測試2");
                logger.error("submit task occurs exception ", e);
            }
        }
    };

    /**
     * 在這裏處理您收到消息後的具體業務邏輯。
     */
    private static void processMessage(Message message) {
        try {
            System.out.println("測試3");
            byte[] body = message.getBody(byte[].class);
            String content = new String(body);
            String topic = message.getStringProperty("topic");
            String messageId = message.getStringProperty("messageId");
            logger.info("receive message"
                    + ", topic = " + topic
                    + ", messageId = " + messageId
                    + ", content = " + content);
        } catch (Exception e) {
            logger.error("processMessage occurs error ", e);
        }
    }

    private static JmsConnectionListener myJmsConnectionListener = new JmsConnectionListener() {
        /**
         * 連接成功建立
         */
        @Override
        public void onConnectionEstablished(URI remoteURI) {
            System.out.println("連接成功");
            logger.info("onConnectionEstablished, remoteUri:{}", remoteURI);
        }

        /**
         * 嘗試過最大重試次數之後，最終連接失敗。
         */
        @Override
        public void onConnectionFailure(Throwable error) {
            System.out.println("試過最大重試次數之後，最終連接失敗。");
            logger.error("onConnectionFailure, {}", error.getMessage());
        }

        /**
         * 連接中斷。
         */
        @Override
        public void onConnectionInterrupted(URI remoteURI) {
            System.out.println("連接中斷。");
            logger.info("onConnectionInterrupted, remoteUri:{}", remoteURI);
        }

        /**
         * 連接中斷後又自動重連上。
         */
        @Override
        public void onConnectionRestored(URI remoteURI) {
            System.out.println("連接中斷後又自動重連上。");
            logger.info("onConnectionRestored, remoteUri:{}", remoteURI);
        }

        @Override
        public void onInboundMessage(JmsInboundMessageDispatch envelope) {}

        @Override
        public void onSessionClosed(Session session, Throwable cause) {}

        @Override
        public void onConsumerClosed(MessageConsumer consumer, Throwable cause) {}

        @Override
        public void onProducerClosed(MessageProducer producer, Throwable cause) {}
    };

    /**
     * password簽名計算方法，請參見上一篇文檔：AMQP客戶端接入說明。
     */
    private static String doSign(String toSignString, String secret, String signMethod) throws Exception {
        SecretKeySpec signingKey = new SecretKeySpec(secret.getBytes(), signMethod);
        Mac mac = Mac.getInstance(signMethod);
        mac.init(signingKey);
        byte[] rawHmac = mac.doFinal(toSignString.getBytes());
        return Base64.encodeBase64String(rawHmac);
    }
}