MQTT初体验mosquitto的java实现
2017年02月10日 17:28:45
阅读数:15702
上节简单描述了mosquitto的安装,与测试,本节继续MQTT使用java语言如何简单调用;
以上例子原型来源于网络,经过自己调试可用,目前仅限于代码的示例;
类:
ServerMQTT
ClientMQTT
PushCallback
注: 例子中需要修改的地方:
1、localhost: 修改为上节安装服务的ip地址;
2、1883:修改为上节安装服务的端口,在配置文件中可修改,默认是(1883);
ServerMQTT类:
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/**
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* Created by Administrator on 17-2-10.
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*/
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import org.eclipse.paho.client.mqttv3.MqttClient;
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import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
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import org.eclipse.paho.client.mqttv3.MqttDeliveryToken;
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import org.eclipse.paho.client.mqttv3.MqttException;
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import org.eclipse.paho.client.mqttv3.MqttMessage;
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import org.eclipse.paho.client.mqttv3.MqttPersistenceException;
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import org.eclipse.paho.client.mqttv3.MqttTopic;
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import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
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/**
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*
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* Title:Server
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* Description: 服务器向多个客户端推送主题,即不同客户端可向服务器订阅相同主题
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* @author admin
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* 2017年2月10日下午17:41:10
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*/
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public class ServerMQTT {
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//tcp://MQTT安装的服务器地址:MQTT定义的端口号
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public static final String HOST = "tcp://localhost:1883";
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//定义一个主题
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public static final String TOPIC = "topic11";
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//定义MQTT的ID,可以在MQTT服务配置中指定
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private static final String clientid = "server11";
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private MqttClient client;
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private MqttTopic topic11;
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private String userName = "mosquitto";
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private String passWord = "";
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private MqttMessage message;
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/**
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* 构造函数
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* @throws MqttException
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*/
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public ServerMQTT() throws MqttException {
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// MemoryPersistence设置clientid的保存形式,默认为以内存保存
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client = new MqttClient(HOST, clientid, new MemoryPersistence());
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connect();
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}
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/**
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* 用来连接服务器
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*/
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private void connect() {
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MqttConnectOptions options = new MqttConnectOptions();
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options.setCleanSession(false);
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options.setUserName(userName);
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options.setPassword(passWord.toCharArray());
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// 设置超时时间
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options.setConnectionTimeout(10);
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// 设置会话心跳时间
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options.setKeepAliveInterval(20);
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try {
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client.setCallback(new PushCallback());
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client.connect(options);
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topic11 = client.getTopic(TOPIC);
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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/**
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*
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* @param topic
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* @param message
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* @throws MqttPersistenceException
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* @throws MqttException
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*/
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public void publish(MqttTopic topic , MqttMessage message) throws MqttPersistenceException,
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MqttException {
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MqttDeliveryToken token = topic.publish(message);
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token.waitForCompletion();
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System.out.println("message is published completely! "
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+ token.isComplete());
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}
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/**
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* 启动入口
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* @param args
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* @throws MqttException
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*/
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public static void main(String[] args) throws MqttException {
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ServerMQTT server = new ServerMQTT();
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server.message = new MqttMessage();
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server.message.setQos(1);
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server.message.setRetained(true);
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server.message.setPayload("hello,topic11".getBytes());
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server.publish(server.topic11 , server.message);
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System.out.println(server.message.isRetained() + "------ratained状态");
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}
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}
ClientMQTT类:
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/**
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*
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* Description:
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* @author admin
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* 2017年2月10日下午17:50:15
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*/
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import java.util.concurrent.ScheduledExecutorService;
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import org.eclipse.paho.client.mqttv3.MqttClient;
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import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
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import org.eclipse.paho.client.mqttv3.MqttException;
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import org.eclipse.paho.client.mqttv3.MqttTopic;
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import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
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public class ClientMQTT {
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public static final String HOST = "tcp://localhost:1883";
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public static final String TOPIC = "topic11";
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private static final String clientid = "client11";
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private MqttClient client;
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private MqttConnectOptions options;
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private String userName = "admin";
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private String passWord = "password";
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private ScheduledExecutorService scheduler;
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private void start() {
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try {
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// 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
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client = new MqttClient(HOST, clientid, new MemoryPersistence());
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// MQTT的连接设置
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options = new MqttConnectOptions();
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// 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
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options.setCleanSession(true);
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// 设置连接的用户名
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options.setUserName(userName);
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// 设置连接的密码
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options.setPassword(passWord.toCharArray());
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// 设置超时时间 单位为秒
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options.setConnectionTimeout(10);
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// 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
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options.setKeepAliveInterval(20);
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// 设置回调
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client.setCallback(new PushCallback());
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MqttTopic topic = client.getTopic(TOPIC);
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//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
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options.setWill(topic, "close".getBytes(), 2, true);
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client.connect(options);
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//订阅消息
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int[] Qos = {1};
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String[] topic1 = {TOPIC};
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client.subscribe(topic1, Qos);
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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public static void main(String[] args) throws MqttException {
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ClientMQTT client = new ClientMQTT();
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client.start();
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}
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}
PushCallback类:
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/**
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*
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* Description:
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* @author admin
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* 2017年2月10日下午18:04:07
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*/
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import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
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import org.eclipse.paho.client.mqttv3.MqttCallback;
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import org.eclipse.paho.client.mqttv3.MqttMessage;
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/**
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* 发布消息的回调类
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*
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* 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。
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* 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。
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* 在回调中,将它用来标识已经启动了该回调的哪个实例。
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* 必须在回调类中实现三个方法:
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*
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* public void messageArrived(MqttTopic topic, MqttMessage message)接收已经预订的发布。
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*
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* public void connectionLost(Throwable cause)在断开连接时调用。
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*
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* public void deliveryComplete(MqttDeliveryToken token))
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* 接收到已经发布的 QoS 1 或 QoS 2 消息的传递令牌时调用。
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* 由 MqttClient.connect 激活此回调。
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*
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*/
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public class PushCallback implements MqttCallback {
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public void connectionLost(Throwable cause) {
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// 连接丢失后,一般在这里面进行重连
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System.out.println("连接断开,可以做重连");
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}
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public void deliveryComplete(IMqttDeliveryToken token) {
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System.out.println("deliveryComplete---------" + token.isComplete());
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}
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public void messageArrived(String topic, MqttMessage message) throws Exception {
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// subscribe后得到的消息会执行到这里面
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System.out.println("接收消息主题 : " + topic);
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System.out.println("接收消息Qos : " + message.getQos());
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System.out.println("接收消息内容 : " + new String(message.getPayload()));
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}
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}
server类启动的结果:
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deliveryComplete---------true
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message is published completely! true
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true------ratained状态
client类启动的结果:
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接收消息主题 : topic11
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接收消息Qos : 1
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接收消息内容 : hello,topic11
具体代码实现,Idea下直接可以执行,需要配置maven
http://download.csdn.net/detail/shch2048/9753269
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