基于：Eclipse paho 的MQTT Java客户端实现数据的发送和接收

MQTT(MQ Telemetry Transport)是IBM开发的一种网络应用层的协议

使用场景：

1、不可靠、网络带宽小的网络

2、运行的设备CPU、内存非常有限

特点：

1、基于发布/订阅模型的协议

2、他是二进制协议，二进制的特点就是紧凑、占用空间小。他的协议头只有2个字节

3、提供了三种消息可能性保障：最多一次 0、最少一次 1、只有一次 2

maven依赖

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1. <dependency>  
2.     <groupId>org.eclipse.paho</groupId>  
3.     <artifactId>org.eclipse.paho.client.mqttv3</artifactId>  
4.     <version>1.1.1</version>  
5. </dependency>  

发送消息示例

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1. import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;  
2. import org.eclipse.paho.client.mqttv3.MqttCallback;  
3. import org.eclipse.paho.client.mqttv3.MqttClient;  
4. import org.eclipse.paho.client.mqttv3.MqttConnectOptions;  
5. import org.eclipse.paho.client.mqttv3.MqttException;  
6. import org.eclipse.paho.client.mqttv3.MqttMessage;  
7. import org.eclipse.paho.client.mqttv3.MqttPersistenceException;  
8. import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;  
9.   
10. /** 
11.  * 发送数据到mqtt服务器 
12.  * @author：涂有 
13.  * @date 2017年8月16日 下午11:15:22 
14.  */  
15. public class PubMsg {  
16.     private static int qos = 2; //只有一次  
17.     private static String broker = "tcp://10.100.124.206:1883";  
18.     private static String userName = "tuyou";  
19.     private static String passWord = "tuyou";  
20.   
21.       
22.     private static MqttClient connect(String clientId,String userName,  
23.             String password) throws MqttException {  
24.         MemoryPersistence persistence = new MemoryPersistence();  
25.         MqttConnectOptions connOpts = new MqttConnectOptions();  
26.         connOpts.setCleanSession(true);  
27.         connOpts.setUserName(userName);  
28.         connOpts.setPassword(password.toCharArray());  
29.         connOpts.setConnectionTimeout(10);  
30.         connOpts.setKeepAliveInterval(20);  
31. //      String[] uris = {"tcp://10.100.124.206:1883","tcp://10.100.124.207:1883"};  
32. //      connOpts.setServerURIs(uris);  //起到负载均衡和高可用的作用  
33.         MqttClient mqttClient = new MqttClient(broker, clientId, persistence);  
34.         mqttClient.setCallback(new PushCallback("test"));  
35.         mqttClient.connect(connOpts);  
36.         return mqttClient;  
37.     }  
38.   
39.     private static void pub(MqttClient sampleClient, String msg,String topic)   
40.             throws MqttPersistenceException, MqttException {  
41.         MqttMessage message = new MqttMessage("ertwersdfas".getBytes());  
42.         message.setQos(qos);  
43.         message.setRetained(false);  
44.         sampleClient.publish(topic, message);  
45.     }  
46.       
47.     private static void publish(String str,String clientId,String topic) throws MqttException{  
48.         MqttClient mqttClient = connect(clientId,userName,passWord);  
49.   
50.         if (mqttClient != null) {  
51.             pub(mqttClient, str, topic);  
52.             System.out.println("pub-->" + str);  
53.         }  
54.   
55.         if (mqttClient != null) {  
56.             mqttClient.disconnect();  
57.         }  
58.     }  
59.   
60.     public static void main(String[] args) throws MqttException {  
61.         publish("message content","client-id-0","$share/edge/server/public/a");  
62.     }  
63. }  
64.   
65. class PushCallback implements MqttCallback {  
66.     private String threadId;  
67.     public PushCallback(String threadId){  
68.         this.threadId = threadId;  
69.     }  
70.       
71.     public void connectionLost(Throwable cause) {  
72.           
73.     }  
74.   
75.     public void deliveryComplete(IMqttDeliveryToken token) {  
76. //       System.out.println("deliveryComplete---------" + token.isComplete());  
77.     }  
78.   
79.     public void messageArrived(String topic, MqttMessage message) throws Exception {  
80.         String msg = new String(message.getPayload());  
81.         System.out.println(threadId + " " + msg);  
82.     }  
83. }  

消费消息示例

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1. import org.eclipse.paho.client.mqttv3.MqttClient;  
2. import org.eclipse.paho.client.mqttv3.MqttConnectOptions;  
3. import org.eclipse.paho.client.mqttv3.MqttException;  
4. import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;  
5.   
6. public class SubMsg {  
7.   
8. //   private static String topic = "$share/testgroup/wyptest1";  
9. //   private static String topic = "$queue/wyptest1";  
10. //   private static String topic = "wyptest1";  
11.      private static int qos = 2;  
12.      private static String broker = "tcp://10.100.124.207:1883";  
13.      private static String userName = "tuyou";  
14.      private static String passWord = "tuyou";  
15.       
16.   
17.      private static MqttClient connect(String clientId) throws MqttException{  
18.          MemoryPersistence persistence = new MemoryPersistence();  
19.          MqttConnectOptions connOpts = new MqttConnectOptions();  
20. //       String[] uris = {"tcp://10.100.124.206:1883","tcp://10.100.124.206:1883"};  
21.          connOpts.setCleanSession(false);  
22.          connOpts.setUserName(userName);  
23.          connOpts.setPassword(passWord.toCharArray());  
24.          connOpts.setConnectionTimeout(10);  
25.          connOpts.setKeepAliveInterval(20);  
26. //         connOpts.setServerURIs(uris);  
27. //         connOpts.setWill(topic, "close".getBytes(), 2, true);  
28.          MqttClient mqttClient = new MqttClient(broker, clientId, persistence);  
29.          mqttClient.connect(connOpts);  
30.          return mqttClient;  
31.      }  
32.        
33.      public static void sub(MqttClient mqttClient,String topic) throws MqttException{  
34.          int[] Qos  = {qos};  
35.          String[] topics = {topic};  
36.          mqttClient.subscribe(topics, Qos);  
37.      }  
38.        
39.        
40.     private static void runsub(String clientId, String topic) throws MqttException{  
41.         MqttClient mqttClient = connect(clientId);  
42.         if(mqttClient != null){  
43.             sub(mqttClient,topic);  
44.         }  
45.     }  
46.     public static void main(String[] args) throws MqttException{  
47.           
48.         runsub("client-id-1", "$share/testgroupa/edge/server/private/+");  
49.     }  
50. }