MQTT的学习之Mosquitto发布-订阅（2）
在《MQTT的学习之Mosquitto安装&使用（1）》一文末尾，我已经模拟了发布-订阅模式，只是那时在服务器直接模拟的，并不是java代码模拟的。下面贴出Java代码
1、首先引入依赖包：
<!-- mosquitto依赖 --> <dependency> <groupId>org.eclipse.paho</groupId> <artifactId>org.eclipse.paho.client.mqttv3</artifactId> <version>1.1.0</version> </dependency>
2、代码
ClientMQTT：
package org.mqtt.model; import org.eclipse.paho.client.mqttv3.MqttClient; import org.eclipse.paho.client.mqttv3.MqttConnectOptions; import org.eclipse.paho.client.mqttv3.MqttException; import org.eclipse.paho.client.mqttv3.MqttTopic; import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence; public class ClientMQTT { public static final String HOST = "tcp://192.168.238.133:1883"; public static final String TOPIC = "sensor"; private static final String clientid = "client11"; private MqttClient client; private MqttConnectOptions options; private String userName = "admin"; private String passWord = "password"; private void start() { try { // host为主机名，clientid即连接MQTT的客户端ID，一般以唯一标识符表示，MemoryPersistence设置clientid的保存形式，默认为以内存保存 client = new MqttClient(HOST, clientid, new MemoryPersistence()); // MQTT的连接设置 options = new MqttConnectOptions(); // 设置是否清空session,这里如果设置为false表示服务器会保留客户端的连接记录，这里设置为true表示每次连接到服务器都以新的身份连接 options.setCleanSession(true); // 设置连接的用户名 options.setUserName(userName); // 设置连接的密码 options.setPassword(passWord.toCharArray()); // 设置超时时间 单位为秒 options.setConnectionTimeout(10); // 设置会话心跳时间 单位为秒 服务器会每隔1.5*20秒的时间向客户端发送个消息判断客户端是否在线，但这个方法并没有重连的机制 options.setKeepAliveInterval(20); // 设置回调 client.setCallback(new PushCallback()); MqttTopic topic = client.getTopic(TOPIC); //setWill方法，如果项目中需要知道客户端是否掉线可以调用该方法。设置最终端口的通知消息 options.setWill(topic, "close".getBytes(), 2, true); client.connect(options); //订阅消息 int[] Qos = {1}; String[] topic1 = {TOPIC}; client.subscribe(topic1, Qos); } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) throws MqttException { ClientMQTT client = new ClientMQTT(); client.start(); } }
PushCallback：
package org.mqtt.model; import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken; import org.eclipse.paho.client.mqttv3.MqttCallback; import org.eclipse.paho.client.mqttv3.MqttMessage; /** * 发布消息的回调类 * * 必须实现MqttCallback的接口并实现对应的相关接口方法 ◦CallBack 类将实现 * MqttCallBack。每个客户机标识都需要一个回调实例。在此示例中 * ，构造函数传递客户机标识以另存为实例数据。在回调中，将它用来标识已经启动了该回调的哪个实例。 ◦必须在回调类中实现三个方法： * * public void messageArrived(MqttTopic topic, MqttMessage message) 接收已经预订的发布。 * * public void connectionLost(Throwable cause) 在断开连接时调用。 * * public void deliveryComplete(MqttDeliveryToken token)) 接收到已经发布的 QoS 1 或 QoS 2 * 消息的传递令牌时调用。 ◦由 MqttClient.connect 激活此回调。 * */ public class PushCallback implements MqttCallback { public void connectionLost(Throwable cause) { // 连接丢失后，一般在这里面进行重连 System.out.println("连接断开，可以做重连"); } @Override public void deliveryComplete(IMqttDeliveryToken arg0) { // publish后会执行到这里 System.out.println("deliveryComplete---------" + arg0.isComplete()); } @Override public void messageArrived(String arg0, MqttMessage arg1) throws Exception { System.out.println("接收消息主题:" + arg0); System.out.println("接收消息Qos:" + arg1.getQos()); System.out.println("接收消息内容:" + new String(arg1.getPayload())); } }
ServerMQTT：
package org.mqtt.model; /** * Created by Administrator on 17-2-10. */ import org.eclipse.paho.client.mqttv3.MqttClient; import org.eclipse.paho.client.mqttv3.MqttConnectOptions; import org.eclipse.paho.client.mqttv3.MqttDeliveryToken; import org.eclipse.paho.client.mqttv3.MqttException; import org.eclipse.paho.client.mqttv3.MqttMessage; import org.eclipse.paho.client.mqttv3.MqttPersistenceException; import org.eclipse.paho.client.mqttv3.MqttTopic; import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence; public class ServerMQTT { //tcp://MQTT安装的服务器地址:MQTT定义的端口号 public static final String HOST = "tcp://192.168.238.133:1883"; //public static final String HOST = "tcp://10.10.10.201:1883"; //定义一个主题 public static final String TOPIC = "sensor"; //定义MQTT的ID，可以在MQTT服务配置中指定 private static final String clientid = "server11"; private MqttClient client; private MqttTopic topic11; private String userName = "mosquitto"; private String passWord = ""; private MqttMessage message; /** * 构造函数 * @throws MqttException */ public ServerMQTT() throws MqttException { // MemoryPersistence设置clientid的保存形式，默认为以内存保存 client = new MqttClient(HOST, clientid, new MemoryPersistence()); connect(); } /** * 用来连接服务器 */ private void connect() { MqttConnectOptions options = new MqttConnectOptions(); options.setCleanSession(false); options.setUserName(userName); options.setPassword(passWord.toCharArray()); // 设置超时时间 options.setConnectionTimeout(10); // 设置会话心跳时间 options.setKeepAliveInterval(20); try { client.setCallback(new PushCallback()); client.connect(options); topic11 = client.getTopic(TOPIC); } catch (Exception e) { e.printStackTrace(); } } /** * * @param topic * @param message * @throws MqttPersistenceException * @throws MqttException */ public void publish(MqttTopic topic , MqttMessage message) throws MqttPersistenceException, MqttException { MqttDeliveryToken token = topic.publish(message); token.waitForCompletion(); System.out.println("message is published completely! " + token.isComplete()); } /** * 启动入口 * @param args * @throws MqttException */ public static void main(String[] args) throws MqttException { ServerMQTT server = new ServerMQTT(); server.message = new MqttMessage(); server.message.setQos(1); server.message.setRetained(true); // server.message.setPayload("hello,topic11".getBytes()); for(int i = 0; i < 1000000;i++){ server.message.setPayload(("hello,see" + i).getBytes()); server.publish(server.topic11 , server.message); } // server.publish(server.topic11 , server.message); System.out.println(server.message.isRetained() + "------ratained状态"); } }
经过测试：ClientMQTT可以实时接收到ServerMQTT发送的数据