在上面两篇关于mqtt的broker的启动和mqtt的服务端发布主题信息之后,我们客户端需要订阅相关的信息并接收相关的主题信息。
package com.etrip.mqtt; import java.net.URISyntaxException; import org.fusesource.mqtt.client.BlockingConnection; import org.fusesource.mqtt.client.MQTT; import org.fusesource.mqtt.client.Message; import org.fusesource.mqtt.client.QoS; import org.fusesource.mqtt.client.Topic; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * * MQTT moquette 的Client 段用于订阅主题,并接收主题信息 * * 采用阻塞式 订阅主题 * * @author longgangbai */ public class MQTTClient { private static final Logger LOG = LoggerFactory.getLogger(MQTTClient.class); private final static String CONNECTION_STRING = "tcp://192.168.208.46:1883"; private final static boolean CLEAN_START = true; private final static short KEEP_ALIVE = 30;// 低耗网络,但是又需要及时获取数据,心跳30s private final static String CLIENT_ID = "publishService"; public static Topic[] topics = { new Topic("china/beijing", QoS.EXACTLY_ONCE), new Topic("china/tianjin", QoS.AT_LEAST_ONCE), new Topic("china/henan", QoS.AT_MOST_ONCE)}; public final static long RECONNECTION_ATTEMPT_MAX=6; public final static long RECONNECTION_DELAY=2000; public final static int SEND_BUFFER_SIZE=2*1024*1024;//发送最大缓冲为2M public static void main(String[] args) { //创建MQTT对象 MQTT mqtt = new MQTT(); BlockingConnection connection=null; try { //设置mqtt broker的ip和端口 mqtt.setHost(CONNECTION_STRING); //连接前清空会话信息 mqtt.setCleanSession(CLEAN_START); //设置重新连接的次数 mqtt.setReconnectAttemptsMax(RECONNECTION_ATTEMPT_MAX); //设置重连的间隔时间 mqtt.setReconnectDelay(RECONNECTION_DELAY); //设置心跳时间 mqtt.setKeepAlive(KEEP_ALIVE); //设置缓冲的大小 mqtt.setSendBufferSize(SEND_BUFFER_SIZE); //获取mqtt的连接对象BlockingConnection connection = mqtt.blockingConnection(); //MQTT连接的创建 connection.connect(); //创建相关的MQTT 的主题列表 Topic[] topics = {new Topic("china/beijing", QoS.AT_LEAST_ONCE)}; //订阅相关的主题信息 byte[] qoses = connection.subscribe(topics); // while(true){ //接收订阅的消息内容 Message message = connection.receive(); //获取订阅的消息内容 byte[] payload = message.getPayload(); // process the message then: LOG.info("MQTTClient Message Topic="+message.getTopic()+" Content :"+new String(payload)); //签收消息的回执 message.ack(); Thread.sleep(2000); } } catch (URISyntaxException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ try { connection.disconnect(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }