使用eclipse paho在java端實現MQTT訊息的收發(客戶端與服務端例項)
一、MQTT(訊息佇列)簡介
MQTT(MQ Telemetry Transport)是IBM開發的一種網路應用層的協議,提供輕量級的,支援可釋出/可訂閱的的訊息推送模式,使裝置對裝置之間的短訊息通訊變得簡單,比如現在應用廣泛的低功耗感測器,手機、嵌入式計算機、微型控制器等移動裝置。
常用的有eclipse paho、activeMQ、阿里MQTT和其他的實現,本例項使用paho
1、使用場景:
1、不可靠、網路頻寬小的網路
2、執行的裝置CPU、記憶體非常有限
(我個人主要是用在服務端與嵌入式客戶端進行訊息和廣告的通訊)
2、特點:
1、基於釋出/訂閱模型的協議
2、他是二進位制協議,二進位制的特點就是緊湊、佔用空間小。他的協議頭只有2個位元組
3、提供了三種訊息可能性保障(Qos):0:最多一次 、1:最少一次 、2:只有一次
3、關鍵字
1、HOST:搭載MQTT的伺服器地址
2、TOPIC:訊息主題,可以被客戶端訂閱,實現對應訊息的收發
3、clientId:客戶端ID,用於伺服器對不同客戶端的識別
4、subscribe/unsubscribe:客戶端對訊息主題的訂閱和取消訂閱
5、Qos:訊息的服務質量,當網路過載或擁塞時,QoS 能確保重要業務量不受延遲或丟棄
6、Callback:當客戶端收到訊息後對訊息的處理(回撥)
7、KeepAliveInterval:客戶端與伺服器之間的連線是通過傳送心跳包來保持存活
二、JAVA端例項
首先匯入所依賴jar包
1、服務端程式碼(負責訊息的傳送)
package com.sc.util.paho;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.MqttPersistenceException;
import org.eclipse.paho.client.mqttv3.MqttTopic;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
/**
* Title:Server 這是傳送訊息的服務端
* Description: 伺服器向多個客戶端推送主題,即不同客戶端可向伺服器訂閱相同主題
* @author rao
*/
public class ServerMQTT {
//tcp://MQTT安裝的伺服器地址:MQTT定義的埠號
public static final String HOST = "tcp://dev.****.com.cn:1883";
//定義一個主題
public static final String TOPIC = "pos_message_all";
//定義MQTT的ID,可以在MQTT服務配置中指定
private static final String clientid = "server11";
private MqttClient client;
private MqttTopic topic11;
private String userName = "paho"; //非必須
private String passWord = ""; //非必須
private MqttMessage message;
/**
* 建構函式
* @throws MqttException
*/
public ServerMQTT() throws MqttException {
// MemoryPersistence設定clientid的儲存形式,預設為以記憶體儲存
client = new MqttClient(HOST, clientid, new MemoryPersistence());
connect();
}
/**
* 用來連線伺服器
*/
private void connect() {
MqttConnectOptions options = new MqttConnectOptions();
options.setCleanSession(false);
options.setUserName(userName);
options.setPassword(passWord.toCharArray());
// 設定超時時間
options.setConnectionTimeout(10);
// 設定會話心跳時間
options.setKeepAliveInterval(20);
try {
client.setCallback(new PushCallback());
client.connect(options);
topic11 = client.getTopic(TOPIC);
} catch (Exception e) {
e.printStackTrace();
}
}
/**
*
* @param topic
* @param message
* @throws MqttPersistenceException
* @throws MqttException
*/
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());
}
/**
* 啟動入口
* @param args
* @throws MqttException
*/
public static void main(String[] args) throws MqttException {
ServerMQTT server = new ServerMQTT();
server.message = new MqttMessage();
server.message.setQos(1); //保證訊息能到達一次
server.message.setRetained(true);
server.message.setPayload("這是推送訊息的內容".getBytes());
server.publish(server.topic11 , server.message);
System.out.println(server.message.isRetained() + "------ratained狀態");
}
}
2、對訊息進行處理的回撥函式程式碼(必須)
package com.sc.util.paho;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttMessage;
/**
* 釋出訊息的回撥類
*
* 必須實現MqttCallback的介面並實現對應的相關介面方法CallBack 類將實現 MqttCallBack。
* 每個客戶機標識都需要一個回撥例項。在此示例中,建構函式傳遞客戶機標識以另存為例項資料。
* 在回撥中,將它用來標識已經啟動了該回調的哪個例項。
* 必須在回撥類中實現三個方法:
*
* public void messageArrived(MqttTopic topic, MqttMessage message)接收已經預訂的釋出。
*
* public void connectionLost(Throwable cause)在斷開連線時呼叫。
*
* public void deliveryComplete(MqttDeliveryToken token))
* 接收到已經發布的 QoS 1 或 QoS 2 訊息的傳遞令牌時呼叫。
* 由 MqttClient.connect 啟用此回撥。
*
*/
public class PushCallback implements MqttCallback {
public void connectionLost(Throwable cause) {
// 連線丟失後,一般在這裡面進行重連
System.out.println("連線斷開,可以做重連");
}
public void deliveryComplete(IMqttDeliveryToken token) {
System.out.println("deliveryComplete---------" + token.isComplete());
}
public void messageArrived(String topic, MqttMessage message) throws Exception {
// subscribe後得到的訊息會執行到這裡面
System.out.println("接收訊息主題 : " + topic);
System.out.println("接收訊息Qos : " + message.getQos());
System.out.println("接收訊息內容 : " + new String(message.getPayload()));
}
}
3、客戶端程式碼(接收訊息)
package com.sc.util.paho;
import java.util.concurrent.ScheduledExecutorService;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttTopic;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
/**
* 模擬一個客戶端接收訊息
* @author rao
*
*/
public class ClientMQTT {
public static final String HOST = "tcp://dev.****.com.cn:1883";
public static final String TOPIC1 = "pos_message_all";
private static final String clientid = "client11";
private MqttClient client;
private MqttConnectOptions options;
private String userName = "admin"; //非必須
private String passWord = "password"; //非必須
@SuppressWarnings("unused")
private ScheduledExecutorService scheduler;
private void start() {
try {
// host為主機名,clientid即連線MQTT的客戶端ID,一般以唯一識別符號表示,MemoryPersistence設定clientid的儲存形式,預設為以記憶體儲存
client = new MqttClient(HOST, clientid, new MemoryPersistence());
// MQTT的連線設定
options = new MqttConnectOptions();
// 設定是否清空session,這裡如果設定為false表示伺服器會保留客戶端的連線記錄,設定為true表示每次連線到伺服器都以新的身份連線
options.setCleanSession(false);
// 設定連線的使用者名稱
options.setUserName(userName);
// 設定連線的密碼
options.setPassword(passWord.toCharArray());
// 設定超時時間 單位為秒
options.setConnectionTimeout(10);
// 設定會話心跳時間 單位為秒 伺服器會每隔1.5*20秒的時間向客戶端傳送個訊息判斷客戶端是否線上,但這個方法並沒有重連的機制
options.setKeepAliveInterval(20);
// 設定回撥
client.setCallback(new PushCallback());
MqttTopic topic = client.getTopic(TOPIC1);
//setWill方法,如果專案中需要知道客戶端是否掉線可以呼叫該方法。設定最終埠的通知訊息
//遺囑 options.setWill(topic, "close".getBytes(), 2, true);
client.connect(options);
//訂閱訊息
int[] Qos = {1};
String[] topic1 = {TOPIC1};
client.subscribe(topic1, Qos);
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws MqttException {
ClientMQTT client = new ClientMQTT();
client.start();
}
}
4、執行以上程式碼需要配置伺服器
常用的搭建MQTT伺服器的軟體是mosquitto,是一款實現了訊息推送協議 MQTT v3.1 的開源訊息代理軟體,可以很方便的搭載在linux、windows伺服器上,我是搭載在linux伺服器上使用。
mosquitto自帶有許多TOPIC(主題)供我們訂閱使用,可以實時的對伺服器狀態進行監測和狀態響應以及統計,包括可以監測到當前連線的客戶端數,某時間段內訊息收發的總量等。
關於伺服器的配置可參考:http://www.cnblogs.com/Free-Thinker/p/5559816.html
mosquito內建主題具體可參考:http://blog.csdn.net/qhdcsj/article/details/44630201
三、將以上程式碼調整為工具類供其他專案呼叫
1、服務端程式碼及呼叫例項
1)服務端程式碼(需要引入之前的回撥函式)
package com.scpos.util;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.MqttPersistenceException;
import org.eclipse.paho.client.mqttv3.MqttTopic;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
/**
* Title:Server 這是傳送訊息的服務端
* Description: 伺服器向多個客戶端推送主題,即不同客戶端可向伺服器訂閱相同主題
* @author rao
*/
public class ServerMQTTUtil {
//tcp://MQTT安裝的伺服器地址:MQTT定義的埠號
public static final String HOST = "tcp://dev.****.com.cn:1883";
//定義MQTT的ID,可以在MQTT服務配置中指定
private static final String clientid = "server11";
private MqttClient client;
private MqttTopic mqttTopic;
private String userName = "paho";
private String passWord = "";
/**
* 建構函式
* @throws MqttException
*/
public ServerMQTTUtil(String topic) throws MqttException {
// MemoryPersistence設定clientid的儲存形式,預設為以記憶體儲存
client = new MqttClient(HOST, clientid, new MemoryPersistence());
connect(topic);
}
/**
* 用來連線伺服器
*/
private void connect(String topic) {
MqttConnectOptions options = new MqttConnectOptions();
options.setCleanSession(false);
options.setUserName(userName);
options.setPassword(passWord.toCharArray());
// 設定超時時間
options.setConnectionTimeout(10);
// 設定會話心跳時間
options.setKeepAliveInterval(20);
try {
// client.setCallback(new PushCallback());
client.connect(options);
mqttTopic = client.getTopic(topic);
} catch (Exception e) {
e.printStackTrace();
}
}
//傳送訊息並獲取回執
public void publish(MqttMessage message) throws MqttPersistenceException,
MqttException, InterruptedException {
MqttDeliveryToken token = mqttTopic.publish(message);
token.waitForCompletion();
System.out.println("message is published completely! "
+ token.isComplete());
System.out.println("messageId:" + token.getMessageId());
token.getResponse();
if (client.isConnected())
client.disconnect(10000);
System.out.println("Disconnected: delivery token \"" + token.hashCode()
+ "\" received: " + token.isComplete());
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassWord() {
return passWord;
}
public void setPassWord(String passWord) {
this.passWord = passWord;
}
public MqttTopic getMqttTopic() {
return mqttTopic;
}
public void setMqttTopic(MqttTopic mqttTopic) {
this.mqttTopic = mqttTopic;
}
}
2)呼叫處程式碼
//設定推送訊息體
String sendTime = TimeUtils.getTime();
String msgType = "html";
String title = message.getTitle();
String content = message.getContent();
String createTime = message.getCreateTime();
Map<String, Object> data = new HashMap<String, Object>();
data.put("messageId", messageId);
data.put("msgType", msgType);
data.put("title", title);
data.put("content", content);
data.put("createTime", createTime);
data.put("sendTime", sendTime);
msgType = "posMessage";
Map<String, Object> messageMap = new HashMap<String, Object>();
messageMap.put("msgType", msgType);
messageMap.put("data", data);
String MQTTObject = JSON.toJSONString(messageMap);
System.out.println(MQTTObject);
//將資訊寫入訊息體
MqttMessage mqttMessage = new MqttMessage();
mqttMessage.setQos(1);
mqttMessage.setRetained(true);
mqttMessage.setPayload(MQTTObject.getBytes("UTF-8"));
//根據deviceIdList內容進行topic設定和傳送推送
if (!deviceIdList.equals("all")) {
List deviceList = Arrays.asList(deviceIdList.split(","));
for (int i =0; i < deviceList.size(); i++) {
String topic = "pos_message_" + deviceList.get(i);
ServerMQTTUtil serverMQTTUtil = new ServerMQTTUtil(topic);
serverMQTTUtil.publish(mqttMessage);
System.out.println(mqttMessage.isRetained() + "------ratained狀態");
}
} else {
String topic = "pos_message_all";
ServerMQTTUtil serverMQTTUtil = new ServerMQTTUtil(topic);
serverMQTTUtil.publish(mqttMessage);
System.out.println(mqttMessage.isRetained() + "------ratained狀態");
}
2、客戶端程式碼及呼叫例項
1)客戶端程式碼
package com.sichang.util;
import java.util.concurrent.ScheduledExecutorService;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
/**
* 模擬一個客戶端接收訊息
* @author rao
*
*/
public class ClientSearch {
public static String str="";
public static final String HOST = "tcp://dev.****.com.cn:1883";
//伺服器內建主題,用來監測當前伺服器上連線的客戶端數量($SYS/broker/clients/connected)
public static final String TOPIC1 = "$SYS/broker/clients/connected";
private static final String clientid = "client13";
private MqttClient client;
private MqttConnectOptions options;
private String userName = "admin";
private String passWord = "password";
@SuppressWarnings("unused")
private ScheduledExecutorService scheduler;
public void start() throws MqttException {
// host為主機名,clientid即連線MQTT的客戶端ID,一般以唯一識別符號表示,MemoryPersistence設定clientid的儲存形式,預設為以記憶體儲存
client = new MqttClient(HOST, clientid, new MemoryPersistence());
// MQTT的連線設定
options = new MqttConnectOptions();
// 設定是否清空session,這裡如果設定為false表示伺服器會保留客戶端的連線記錄,設定為true表示每次連線到伺服器都以新的身份連線
options.setCleanSession(false);
// 設定連線的使用者名稱
options.setUserName(userName);
// 設定連線的密碼
options.setPassword(passWord.toCharArray());
// 設定超時時間 單位為秒
options.setConnectionTimeout(10);
// 設定會話心跳時間 單位為秒 伺服器會每隔1.5*20秒的時間向客戶端傳送個訊息判斷客戶端是否線上,但這個方法並沒有重連的機制
options.setKeepAliveInterval(20);
// 設定回撥
client.setCallback(new MqttCallback(){
public void connectionLost(Throwable cause) {
// 連線丟失後,一般在這裡面進行重連
// System.out.println("連線斷開,可以做重連");
}
public void deliveryComplete(IMqttDeliveryToken token) {
System.out.println("deliveryComplete---------" + token.isComplete());
}
public void messageArrived(String topic, MqttMessage message) throws Exception {
try {
str = message.toString();
// System.out.println(" 從伺服器收到的訊息為:"+message.toString());
} catch (Exception e) {
e.printStackTrace();
}
}
});
// MqttTopic topic = client.getTopic(TOPIC1);
// setWill方法,如果專案中需要知道客戶端是否掉線可以呼叫該方法。設定最終埠的通知訊息
// options.setWill(topic, "close".getBytes(), 2, true); //遺囑
client.connect(options);
//訂閱訊息
int[] Qos = {1};
String[] topic1 = {TOPIC1};
client.subscribe(topic1, Qos);
}
@SuppressWarnings("static-access")
//用來給呼叫處返回訊息內容
public String resc() {
return this.str;
}
}
2)呼叫處程式碼
下面執行緒的作用是每三秒鐘返回伺服器上的客戶端連線數
public void runTask() {
final long timeInterval = 2000;// 兩秒執行一次
Runnable runnable = new Runnable() {
public void run() {
while (true) {
// ------- code for task to run
try { //你要執行的程式
ClientSearch clientSearch = new ClientSearch();
try {
clientSearch.start();
} catch (MqttException e) {
e.printStackTrace();
}
Thread.sleep(1000); //給一秒時間接收伺服器訊息
Integer num = Integer.valueOf(clientSearch.resc());
System.out.println("當前客戶端連線數:"+num);
} catch (InterruptedException e) {
e.printStackTrace();
}
// ------- ends here
try {
Thread.sleep(timeInterval);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
Thread thread = new Thread(runnable);
thread.start();
}