MQTT是物联网收发数据的一种协议
Elipse Paho是一个开源项目实现了MQTT的Clinent可以方便直接操纵数据的上传和下载
The Eclipse Paho project provides open-source client implementations of MQTT and MQTT-SN messaging protocols aimed at new, existing, and emerging applications for the Internet of Things (IoT).
发送数据：
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.MqttMessage; 5 import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence; 6 7 /** 8 * 使用同步接口发布一个消息的例子 9 * @author Administrator 10 * 得到的输出 11 Connecting to broker: tcp://iot.eclipse.org:1883 12 Connected 13 Publishing message: Message from MqttPublishSample 14 Message published 15 Disconnected 16 * 17 */ 18 public class MQTT_Client_send { 19 20 public static void main(String[] args) { 21 // TODO Auto-generated method stub 22 23 String topic = "MQTT Examples"; 24 String content = "Message from MqttPublishSample"; 25 int qos = 2; 26 String broker = "tcp://iot.eclipse.org:1883"; 27 String clientId = "JavaSample"; 28 MemoryPersistence persistence = new MemoryPersistence(); 29 30 try { 31 //Create an MqttClient that can be used to communicate with an MQTT server.就是创建client 32 MqttClient sampleClient = new MqttClient(broker, clientId, persistence); 33 //Constructs a new MqttConnectOptions object using the default values.就是创建连接属性 34 MqttConnectOptions connOpts = new MqttConnectOptions(); 35 //Sets whether the client and server should remember state across restarts and reconnects.就是说这个连接是无记忆的 36 connOpts.setCleanSession(true); 37 System.out.println("Connecting to broker: "+broker); 38 //使用连接属性，建立连接 39 sampleClient.connect(connOpts); 40 System.out.println("Connected"); 41 System.out.println("Publishing message: "+content); 42 //得到一个操作系统默认的编码格式的字节数组，Constructs a message with the specified byte array as a payload, and all other values set to defaults.,就是创建一个mqtt消息 43 MqttMessage message = new MqttMessage(content.getBytes()); 44 //Sets the quality of service for this message.Quality of Service 2 - indicates that a message should be delivered once. 45 message.setQos(qos); 46 //调用发布方法，发布一个主题和一个消息 47 sampleClient.publish(topic, message); 48 System.out.println("Message published"); 49 //断开连接 50 sampleClient.disconnect(); 51 System.out.println("Disconnected"); 52 System.exit(0); 53 } catch(MqttException me) { 54 System.out.println("reason "+me.getReasonCode()); 55 System.out.println("msg "+me.getMessage()); 56 System.out.println("loc "+me.getLocalizedMessage()); 57 System.out.println("cause "+me.getCause()); 58 System.out.println("excep "+me); 59 me.printStackTrace(); 60 } 61 } 62 63 64 65 }
接收数据：
1 import java.io.BufferedWriter; 2 import java.io.FileWriter; 3 import java.io.IOException; 4 import java.util.ArrayList; 5 import java.util.List; 6 7 import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken; 8 import org.eclipse.paho.client.mqttv3.MqttCallback; 9 import org.eclipse.paho.client.mqttv3.MqttCallbackExtended; 10 import org.eclipse.paho.client.mqttv3.MqttClient; 11 import org.eclipse.paho.client.mqttv3.MqttConnectOptions; 12 import org.eclipse.paho.client.mqttv3.MqttException; 13 import org.eclipse.paho.client.mqttv3.MqttMessage; 14 import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence; 15 public class MQTT_Client_Receive { 16 17 public static void Write2Files(String filePath,String text) throws IOException { 18 FileWriter fileWriter=new FileWriter(filePath,true); 19 fileWriter.write(""); 20 BufferedWriter bufferedWriter=new BufferedWriter(fileWriter); 21 bufferedWriter.append(text+"\r\n"); 22 bufferedWriter.close(); 23 fileWriter.close(); 24 } 25 26 public static void Mqtt_Client_2_File(String Topic,String Path) throws MqttException, InterruptedException { 27 // String broker="tcp://iotdevrd.chinacloudapp.cn:1889"; 28 // String clientID="5036cf062ade4a28bf74726e5bff895a"; 29 // int qos = 2; 30 // String topic=Topic; 31 // String userName="121"; 32 // String passWord="121"; 33 //内网测试数据 34 String broker="tcp://3.1.2.244:1889"; 35 String clientID="5036cf062ade4a28bf74726e5bff895a"; 36 int qos = 2; 37 String topic=Topic; 38 String userName="121"; 39 String passWord="121"; 40 //内网决赛数据地址 41 // String broker="tcp://3.1.2.244:1889"; 42 // String clientID="5036cf062ade4a28bf74726e5bff895a"; 43 // int qos = 2; 44 // String topic=Topic; 45 // String userName="121"; 46 // String passWord="121"; 47 48 MemoryPersistence persistence = new MemoryPersistence(); 49 50 MqttClient myClient=new MqttClient(broker, clientID, persistence); 51 MqttConnectOptions connectOptions=new MqttConnectOptions(); 52 connectOptions.setUserName(userName); 53 connectOptions.setPassword(passWord.toCharArray()); 54 connectOptions.setCleanSession(true); 55 56 myClient.connect(connectOptions); 57 MqttCallback callback=new MqttCallbackExtended() { 58 @Override 59 public void messageArrived(String arg0, MqttMessage arg1) throws Exception { 60 //String filePath="C:\\eclipse-workspace\\Projects\\IOTProjectPrepare\\src\\123.txt"; 61 String filePath=Path; 62 Write2Files(filePath, arg1.toString()); 63 System.out.println(new String(arg1.toString())); 64 } 65 @Override 66 public void deliveryComplete(IMqttDeliveryToken arg0) { 67 } 68 @Override 69 public void connectionLost(Throwable arg0) { 70 } 71 @Override 72 public void connectComplete(boolean arg0, String arg1) { 73 } 74 }; 75 myClient.setCallback(callback); 76 myClient.subscribe(topic, qos); 77 //监听10秒钟最后断开连接 78 Thread.sleep(20000); 79 if(myClient.isConnected()) 80 myClient.disconnect(); 81 //myClient.disconnect(); 82 //System.exit(0); 83 84 } 85 86 87 public static void Topics2Files(int index, String test_final,long time) throws MqttException, InterruptedException { 88 89 //循环接收的逻辑 90 // ListtopicList=new ArrayList<>(); 91 //// topicList.add("GPSLocation/test1/1"); 92 //// topicList.add("GPSLocation/test1/2"); 93 //// topicList.add("GPSLocation/test2/1"); 94 //// topicList.add("GPSLocation/test2/2"); 95 // topicList.add("GPSLocation/test3/1"); 96 // topicList.add("GPSLocation/test3/2"); 97 //// topicList.add("GPSLocation/test4/1"); 98 //// topicList.add("GPSLocation/test4/2"); 99 // topicList.add("GPSLocation/test6/1"); 100 // topicList.add("GPSLocation/test6/2"); 101 // for (int i = 0; i < topicList.size(); ++i) { 102 // String array_element = topicList.get(i); 103 // String Path="D:\\"+(index)+".json"; 104 // System.out.println(Path); 105 // Mqtt_Client_2_File(array_element, Path); 106 // } 107 //正式比赛一个一个接收，使用下面的逻辑 108 String topic=""; 109 if(test_final.equals("test")) { 110 topic="GPSLocation/test"+index+"/2"; 111 }else if(test_final.equals("final")) { 112 topic="GPULocation/"+index; 113 } 114 System.out.println("当前订阅路径是："+topic); 115 String path="D:\\"+(index)+"_"+time+".json"; 116 System.out.println("当前订阅的保存路径是："+path); 117 Mqtt_Client_2_File(topic, path); 118 119 } 120 public static void main(String[] args) throws MqttException, InterruptedException { 121 //Topics2Files(); 122 long time=System.currentTimeMillis()/1000; 123 Topics2Files(7, "test",time); 124 125 } 126 127 }