最近做了一个Mqtt消息推送，和大家分享分享心得，以防以后搞忘了，新人第一次写博客，大神勿喷。

Apache apollo Mqtt 是一个基于Tcp/Ip协议的消息代理服务器，在物联网方面应用十分广泛。Mqtt 下载

这是我的项目结构，PushCallBack.java 是消息处理类，ServeMqtt.java 是Mqtt代理服务器的配置用的。各个文件内容如下：

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.err.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()));
    }
}

public class ServerMqtt {
	public static final String HOST = "tcp://127.0.0.1:61613";
	public static MqttClient client;
	private MqttTopic topic11;
	private String topicStr;
	private String userName = "admin";
	private String passWord = "password";
	private MqttMessage message;
	private static  ServerMqtt serverMqtt ;

	public static ServerMqtt getServerMQTTInstance() {
		if (null != serverMqtt) {
			return serverMqtt;
		}
		serverMqtt = new ServerMqtt();
		return serverMqtt;
	}

	public void connect( MqttClient client) {
		MqttConnectOptions options = new MqttConnectOptions();
		options.setCleanSession(true);
		options.setUserName(userName);
		options.setPassword(passWord.toCharArray());
		options.setConnectionTimeout(10);
		options.setKeepAliveInterval(20);
	  	try {
			client.setCallback(new PushCallback());
			client.connect(options);
			MqttTopic topic = client.getTopic("154");
			options.setWill(topic, "close".getBytes(), 2, true);
				int[] Qos = { 1 };
				String[] topic1 = { "1008611" };
				client.subscribe(topic1, Qos);
			
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	public static MqttClient getMqttClient(String clientId) throws MqttException {
		if (client != null && clientId.equals(client.getClientId())) {
			return client;
		}
		return new MqttClient(HOST, clientId);
	}

	public void MqttInit( String clientId) throws MqttException {
		MqttClient client1 = ServerMqtt.getMqttClient(clientId);
		if(this.client !=client1){
			this.client = client1;
			connect(client);
		}
		
	}
	public void publish(String topicStr, JSONObject object) throws MqttPersistenceException, MqttException {
		message = new MqttMessage();
		message.setQos(2);
		message.setRetained(true);
		message.setPayload(object.toString().getBytes());
		topic11 = client.getTopic(topicStr);
		MqttDeliveryToken token = topic11.publish(message);
		token.waitForCompletion();
		System.out.println("message is published completely! " + token.isComplete());
	}

}

test1.java 是测试类

note:

   1、开始我看了很多的关于mqtt的博客，都只是实现了一些功能，但是在实际项目开发中，代码就不适用了，实际开发中，需要又很多不通的终端，它们的Clientd不尽相同，在这里要注意了，一个ClientId 只能同时new 一个Client出来，否者会把你之前的挤掉。