1. 启动ActiveMQ:

2. 安装jdk和eclipse

Jdk 官方下载：https://www.oracle.com/cn/java/technologies/downloads/

jdk安装测试：

 eclipse官方下载网站免安装版，解压缩就可以使用：

https://www.eclipse.org/downloads/packages/

3.下载Paho Mqtt的jar包：

Index of /repositories/paho/org/eclipse/paho/mqtt-client/0.4.1-SNAPSHOT

 4.打开eclipse,创建Java project,右击项目，添加路径libs,把上面下载的Paho Mqtt的jar包放进libs路径, Add external jar...

 

5.编写代码

   src源码路径添加两个class:MqttTest,MyMqtt，代码如下：

   MqttTest.java:

public class MyMqtt {

//Mqtt服务器地址，由于本地电脑，所以用本地回环地址作为服务器地址

private String host = "tcp://127.0.0.1:1883";

//登录ActiveMQ的账号信息

private String userName = "admin";

private String passWord = "admin";

//连接服务器的客户端实例client

private MqttClient client;

//存放订阅的主题

private MqttTopic mqttTopic;

//当前主题

private String myTopic = "Topics/htjs/serverToPhone";

//发送消息的主体

private MqttMessage message;

public MyMqtt(String id,MqttCallback callback,boolean cleanSession) {

// TODO Auto-generated constructor stub

try {

//配置连接属性

client = new MqttClient(host,id,new MemoryPersistence());

MqttConnectOptions options = new MqttConnectOptions();

options.setCleanSession(cleanSession);

options.setUserName(userName);

options.setPassword(passWord.toCharArray());

options.setConnectionTimeout(10);

options.setKeepAliveInterval(20);

//设置回调函数

if(callback == null) {

client.setCallback(new MqttCallback(){

@Override

public void connectionLost(Throwable arg0) {

// TODO Auto-generated method stub

System.out.println(id+"connectLost"+arg0);

}

@Override

public void deliveryComplete(IMqttDeliveryToken arg0) {

// TODO Auto-generated method stub

System.out.println(id+"deliveryComplete"+arg0);

}

@Override

public void messageArrived(String arg0, MqttMessage arg1) throws Exception {

// TODO Auto-generated method stub

System.out.println(id+"messageArrived"+arg1.toString());

}});

}else{

client.setCallback(callback);

}

//发起连接

client.connect(options);

}catch(MqttException e) {

e.printStackTrace();

}

}

//添加订阅信息的方法

public void subscribe(String[] topicFilters,int[] qos) {

try {

client.subscribe(topicFilters,qos);

} catch (MqttException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

//添加发布消息的方法

public void sendMessage(String msg) {

sendMessage(myTopic,msg);

}

private void sendMessage(String topic, String msg) {

// TODO Auto-generated method stub

try {

message = new MqttMessage();

message.setQos(1);

message.setRetained(true);

message.setPayload(msg.getBytes());

mqttTopic = client.getTopic(topic);

//发布主题

MqttDeliveryToken token = mqttTopic.publish(message);

token.waitForCompletion();

} catch (MqttException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

  MyMqtt.java:

public class MqttTest {

private static String[] myTopics = {"Topics/Light/SwitchOn","Topics/Light/SwitchOff"};

private static int[] myQos = {2,2};

public static void main(String[] args) {

// TODO Auto-generated method stub

MyMqtt myMqtt = new MyMqtt("client",null,false);

myMqtt.subscribe(myTopics, myQos);

System.out.println("client start...");

}

}

6. 运行代码，注意这时候ActiveMQ是已经启动的！Java编写的id为client的客户端已经启动成功:

7.通信测试

下载Paho MQTT客户端程序（Paho）:

Index of /repositories/paho-releases/org/eclipse/paho/org.eclipse.paho.ui.app/1.1.1

 解压缩，进入路径，启动paho客户端

 添加连接，输入本机1883的服务器地址，连接client客户端，订阅client发布的主题：Topics/htjs/serverToPhone，发布开灯的主题：Topics/Light/SwitchOn，发送的信息为：{value:80}:

打开eclipe项目，可以收到paho客户端刚才发过来的主题和信息：

8.总结

首先开启ActiveMQ服务器平台，用java编写client客户端，发布主题：Topics/htjs/serverToPhone，订阅主题：Topics/Light/SwitchOn，Topics/Light/SwitchOff,在打开paho客户端，连接client客户端，订阅主题：Topics/htjs/serverToPhone，发布主题和消息：Topics/Light/SwitchOn，{value:80}，最后在client客户端收到信息80，网络架构如下图所示：