mqtt 是轻量级基于代理的发布/订阅的消息传输协议，设计思想是开放，简单，轻量级，且易于实现，这些优点使得他受用于任何环境
该协议的特点有:
&使用发布/订阅消息的模式，提供一对多的消息发布，解除应用程序耦合
对负载内容屏蔽的消息传输
使用TCP/IO 提供的网络连接
有三种消息发布服务质量:
& &至多一次&,消息发布完全依赖底层TCP/IP 网络，会发生消息丢失或者重复，这一级别可用于如下情况，环境，传感器数据，丢失一次度记录无所谓，因为不久之后会有第二次发送
& &至少一次& 确保消息到达，但消息重复可能发生
& “只有一次&，确保消息到达一次，这一级别可用于如下情况，在计费系统中，消息重复或者丢失导致不正确的结果
小型传输，开销很小（固定床都的头部是2个字节),协议变换最小化，以降低网络流量
使用Last will和Testament 特性通知有关客户端异常中断的机制
1:配置环境
2：服务器端程序
package com.
import org.eclipse.paho.client.mqttv3.MqttC
import org.eclipse.paho.client.mqttv3.MqttConnectO
import org.eclipse.paho.client.mqttv3.MqttDeliveryT
import org.eclipse.paho.client.mqttv3.MqttE
import org.eclipse.paho.client.mqttv3.MqttM
import org.eclipse.paho.client.mqttv3.MqttPersistenceE
import org.eclipse.paho.client.mqttv3.MqttT
import org.eclipse.paho.client.mqttv3.persist.MemoryP
* 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
* Company Beijing
* date createTime：16/7/13
public class Server {
public static final String HOST = &tcp://101.200.133.189:1883&;
public static final String TOPIC = &toclient/124&;
public static final String TOPIC125 = &toclient/125&;
private static final String clientid = &server&;
private MqttC
private MqttT
private MqttTopic topic125;
private String userName = &admin&;
private String passWord = &password&;
private MqttM
public Server() 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();
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);
client.setCallback(new PushCallback());
client.connect(options);
topic = client.getTopic(TOPIC);
topic125 = client.getTopic(TOPIC125);
} catch (Exception e) {
e.printStackTrace();
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());
public static void main(String[] args) throws MqttException {
Server server = new Server();
server.message = new MqttMessage();
server.message.setQos(2);
server.message.setRetained(true);
server.message.setPayload(&给客户端124推送的信息:wuyouxuan&.getBytes());
server.publish(server.topic, server.message);
server.message = new MqttMessage();
server.message.setQos(2);
server.message.setRetained(true);
server.message.setPayload(&给客户端125推送的信息:wuyouxuan&.getBytes());
server.publish(server.topic125, server.message);
System.out.println(server.message.isRetained() + &------ratained状态&);
package com.
import org.eclipse.paho.client.mqttv3.IMqttDeliveryT
import org.eclipse.paho.client.mqttv3.MqttC
import org.eclipse.paho.client.mqttv3.MqttM
* 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&);
public void deliveryComplete(IMqttDeliveryToken token) {
System.out.println(&deliveryComplete---------& + token.isComplete());
public void messageArrived(String topic, MqttMessage message) throws Exception {
// subscribe后得到的消息会执行到这里面
System.out.println(&接收消息主题 : & + topic);
System.out.println(&接收消息Qos : & + message.getQos());
System.out.println(&接收消息内容 : & + new String(message.getPayload()));
3：客户端程序
package com.
import org.eclipse.paho.client.mqttv3.MqttC
import org.eclipse.paho.client.mqttv3.MqttConnectO
import org.eclipse.paho.client.mqttv3.MqttE
import org.eclipse.paho.client.mqttv3.MqttT
import org.eclipse.paho.client.mqttv3.persist.MemoryP
import java.util.concurrent.ScheduledExecutorS
* Description
客户端程序
* Company Beijing
* date createTime：16/7/13
public class Client {
public static final String HOST = &tcp://101.200.133.189:1883&;
public static final String TOPIC = &toclient/124&;
private static final String clientid = &client124&;
private MqttC
private MqttConnectO
private String userName = &admin&;
private String passWord = &password&;
private ScheduledExecutorS
private void start() {
// 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
String[] topic1 = {TOPIC};
client.subscribe(topic1, Qos);
} catch (Exception e) {
e.printStackTrace();
public static void main(String[] args) throws MqttException {
Client client = new Client();
client.start();
参考网站：
/a/9450#articleHeader0
github 开源项目 &&/fusesource/mqtt-client
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