JAVA开发MQTT总结
MQTT 介绍
- 它是一种 机器之间通讯 machine-to-machine (M2M)、物联网 Internet of Things （IoT）常用的一种轻量级消息传输协议
- 适用于网络带宽较低的场合
- 包含发布、订阅模式，通过一个代理服务器（broker），任何一个客户端（client）都可以订阅或者发布某个主题的消息，然后订阅了该主题的客户端则会收到该消息
mqtt还是之前公司有需求所以写的一个demo，在这里记录下来，方便有人使用的时候查阅，不涉及mqtt的具体讲解，只是贴代码和运行过程。
MQTT的入门，以及特性，协议，结构的讲解，请看下面这篇文章
https://www.runoob.com/w3cnote/mqtt-intro.html
什么是MQTT，它能干什么，它的应用场景在哪里？请参考下面这篇文章
https://www.ibm.com/developerworks/cn/iot/iot-mqtt-why-good-for-iot/index.html
本文中采用的MQTT服务器Apache-Apollo的下载配置搭建过程，请参考下面这篇文章
https://blog.csdn.net/qq_29350001/article/details/76680646
下面就开始创建broker，
RaindeMacBook-Pro:bin rain$ ./apollo create mybroker
Creating apollo instance at: mybroker
Generating ssl keystore...
Warning:
JKS 密钥库使用专用格式。建议使用 "keytool -importkeystore -srckeystore keystore -destkeystore keystore -deststoretype pkcs12" 迁移到行业标准格式 PKCS12。
You can now start the broker by executing:
"/Users/rain/Documents/Soft/apache-apollo-1.7.1/bin/mybroker/bin/apollo-broker" run
Or you can run the broker in the background using:
"/Users/rain/Documents/Soft/apache-apollo-1.7.1/bin/mybroker/bin/apollo-broker-service" start
进入新生成的broker中
RaindeMacBook-Pro:bin rain$ ls
apollo apollo.cmd mybroker testbroker
RaindeMacBook-Pro:bin rain$ cd mybroker/
RaindeMacBook-Pro:mybroker rain$ ls
bin data etc log tmp
RaindeMacBook-Pro:mybroker rain$ cd bin
RaindeMacBook-Pro:bin rain$ ls
apollo-broker apollo-broker-service
可以看到有两个文件，启动apollo-broker
image
启动成功以后，就可以在浏览器中访问了，默认用户名和密码是admin，password
image
刚进去是，Topics选项卡是空的，我是在运行程序后截图的，所以有一个topic列表
image
配置Maven
在pom.xml中添加以下配置
<dependency>
<groupId>org.eclipse.paho</groupId>
<artifactId>org.eclipse.paho.client.mqttv3</artifactId>
<version>1.2.0</version>
</dependency>
再创建下面的类
MqttServer
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
public class MqttServer2 {
/**
* 代理服务器ip地址
*/
public static final String MQTT_BROKER_HOST = "tcp://127.0.0.1:61613";
/**
* 订阅标识
*/
public static final String MQTT_TOPIC = "test2";
private static String userName = "admin";
private static String password = "password";
/**
* 客户端唯一标识
*/
public static final String MQTT_CLIENT_ID = "android_server_xiasuhuei32";
private static MqttTopic topic;
private static MqttClient client;
public static void main(String... args) {
// 推送消息
MqttMessage message = new MqttMessage();
try {
client = new MqttClient(MQTT_BROKER_HOST, MQTT_CLIENT_ID, new MemoryPersistence());
MqttConnectOptions options = new MqttConnectOptions();
options.setCleanSession(true);
options.setUserName(userName);
options.setPassword(password.toCharArray());
options.setConnectionTimeout(10);
options.setKeepAliveInterval(20);
topic = client.getTopic(MQTT_TOPIC);
message.setQos(1);
message.setRetained(false);
message.setPayload("message from server222222".getBytes());
client.connect(options);
while (true) {
MqttDeliveryToken token = topic.publish(message);
token.waitForCompletion();
System.out.println("已经发送222");
Thread.sleep(10000);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
MqttClient
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
public class MyMqttClient {
/**
* 代理服务器ip地址
*/
public static final String MQTT_BROKER_HOST = "tcp://127.0.0.1:61613";
/**
* 客户端唯一标识
*/
public static final String MQTT_CLIENT_ID = "android_xiasuhuei321";
/**
* 订阅标识
*/
// public static final String MQTT_TOPIC = "xiasuhuei321";
/**
*
*/
public static final String USERNAME = "admin";
/**
* 密码
*/
public static final String PASSWORD = "password";
public static final String TOPIC_FILTER = "test2";
private volatile static MqttClient mqttClient;
private static MqttConnectOptions options;
public static void main(String... args) {
try {
// host为主机名，clientid即连接MQTT的客户端ID，一般以客户端唯一标识符表示，
// MemoryPersistence设置clientid的保存形式，默认为以内存保存
mqttClient = new MqttClient(MQTT_BROKER_HOST, MQTT_CLIENT_ID, new MemoryPersistence());
// 配置参数信息
options = new MqttConnectOptions();
// 设置是否清空session,这里如果设置为false表示服务器会保留客户端的连接记录，
// 这里设置为true表示每次连接到服务器都以新的身份连接
options.setCleanSession(true);
// 设置用户名
options.setUserName(USERNAME);
// 设置密码
options.setPassword(PASSWORD.toCharArray());
// 设置超时时间 单位为秒
options.setConnectionTimeout(10);
// 设置会话心跳时间 单位为秒 服务器会每隔1.5*20秒的时间向客户端发送个消息判断客户端是否在线，但这个方法并没有重连的机制
options.setKeepAliveInterval(20);
// 连接
mqttClient.connect(options);
// 订阅
mqttClient.subscribe(TOPIC_FILTER);
// 设置回调
mqttClient.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable throwable) {
System.out.println("connectionLost");
}
@Override
public void messageArrived(String s, MqttMessage mqttMessage) throws Exception {
System.out.println("Topic: " + s + " Message: " + mqttMessage.toString());
}
@Override
public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
}
});
} catch (Exception e) {
e.printStackTrace();
}
}
}
PublishSample
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;
/**
*发布端
*/
public class PublishSample {
public static void main(String[] args) {
String topic = "test2";
String content = "hello 哈哈";
int qos = 1;
String broker = "tcp://127.0.0.1:61613";
String userName = "admin";
String password = "password";
String clientId = "pubClient";
// 内存存储
MemoryPersistence persistence = new MemoryPersistence();
try {
// 创建客户端
MqttClient sampleClient = new MqttClient(broker, clientId, persistence);
// 创建链接参数
MqttConnectOptions connOpts = new MqttConnectOptions();
// 在重新启动和重新连接时记住状态
connOpts.setCleanSession(false);
// 设置连接的用户名
connOpts.setUserName(userName);
connOpts.setPassword(password.toCharArray());
// 建立连接
sampleClient.connect(connOpts);
// 创建消息
MqttMessage message = new MqttMessage(content.getBytes());
// 设置消息的服务质量
message.setQos(qos);
// 发布消息
sampleClient.publish(topic, message);
// 断开连接
sampleClient.disconnect();
// 关闭客户端
sampleClient.close();
} catch (MqttException me) {
System.out.println("reason " + me.getReasonCode());
System.out.println("msg " + me.getMessage());
System.out.println("loc " + me.getLocalizedMessage());
System.out.println("cause " + me.getCause());
System.out.println("excep " + me);
me.printStackTrace();
}
}
}
SubscribeSample
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
/**
*订阅端
*/
public class SubscribeSample {
public static void main(String[] args) throws MqttException {
String HOST = "tcp://127.0.0.1:61613";
String TOPIC = "test2";
int qos = 1;
String clientid = "subClient";
String userName = "admin";
String passWord = "password";
try {
// host为主机名，test为clientid即连接MQTT的客户端ID，一般以客户端唯一标识符表示，MemoryPersistence设置clientid的保存形式，默认为以内存保存
MqttClient client = new MqttClient(HOST, clientid, new MemoryPersistence());
// MQTT的连接设置
MqttConnectOptions options = new MqttConnectOptions();
// 设置是否清空session,这里如果设置为false表示服务器会保留客户端的连接记录，这里设置为true表示每次连接到服务器都以新的身份连接
options.setCleanSession(true);
// 设置连接的用户名
options.setUserName(userName);
// 设置连接的密码
options.setPassword(passWord.toCharArray());
// 设置超时时间 单位为秒
options.setConnectionTimeout(10);
// 设置会话心跳时间 单位为秒 服务器会每隔1.5*20秒的时间向客户端发送个消息判断客户端是否在线，但这个方法并没有重连的机制
options.setKeepAliveInterval(20);
// 设置回调函数
client.setCallback(new MqttCallback() {
public void connectionLost(Throwable cause) {
System.out.println("connectionLost");
}
public void messageArrived(String topic, MqttMessage message) throws Exception {
System.out.println("topic:"+topic);
System.out.println("Qos:"+message.getQos());
System.out.println("message content:"+new String(message.getPayload()));
}
public void deliveryComplete(IMqttDeliveryToken token) {
System.out.println("deliveryComplete---------"+ token.isComplete());
}
});
client.connect(options);
//订阅消息
client.subscribe(TOPIC, qos);
} catch (Exception e) {
e.printStackTrace();
}
}
}
启动程序
1.启动MqttServer2以后，开始循环发送消息。
image
2.启动MyMqttClient开始接收消息。
image
到这里，整个程序基本可以运行。
3.启动PublishSample，发布一条消息，在启动SubscribeSample来订阅发布的消息。
image
4.发布的消息在MyMqttClient中也会显示出来
image
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