简述
基于Paho-mqtt，实现mqtt连接与消息处理
主要功能
- MQTT 连接、重连、断开、消息发送
- 消息的订阅与发布
模块
/*
消息列表
const MESSAGE = {
device_id:{
message_code:message_body
}
}
*/
const MESSAGE = {}
/*
消息订阅列表
const SUBSCRIBER = {
device_id:{
message_code:[
{
page,
callback
}
]
}
}
*/
const SUBSCRIBER = {}
/* 消息到达后，存入MESSAGE*/
function onMqttMessageArrived({topic, payloadString}: { topic: string, payloadString }) {
// 格式化消息
let device_id = topic.split('/')[1]
let {f: message_code, p: message_body} = JSON.parse(payloadString)
console.log('---------------------------------------- message Arrived:', device_id, message_code, message_body)
// 存放消息
if (!(device_id in MESSAGE))
MESSAGE[device_id] = {}
MESSAGE[device_id][message_code] = message_body
// 发布订阅
if ((device_id in SUBSCRIBER) && (message_code in SUBSCRIBER[device_id])) {
let subscribers = SUBSCRIBER[device_id][message_code]
subscribers.forEach(subscriber => {
subscriber.callback({f: message_code, p: message_body}, MESSAGE);
})
}
/*
// 可以考虑将发布订阅放到模块外，通过defineProperty/proxy来监听数据变化
Object.defineProperty(MESSAGE[device_id], message_code, {
get: function () {
},
set: function (value) {
if (!(device_id in SUBSCRIBER)) {
return;
}
if (!(message_code in SUBSCRIBER[device_id])) {
return;
}
let subscribers = SUBSCRIBER[device_id][message_code]
subscribers.forEach(subscriber => {
subscriber.callback({f: message_code, p: value}, MESSAGE);
})
}
})
*/
}
// MQTT类的接口，用来校验public属性与方法
interface MQTT_interface {
mqtt;
url: string;
username: string;
password: string;
useSSL: boolean;
keepAliveInterval: number;
// 设置连接mqtt所需的参数，所有参数可选
setConnectOptions({}: { url?: string, username?: string, password?: string, useSSL?: boolean, keepAliveInterval?: number });
// 建立mqtt连接
connect();
// mqtt重连
reconnect();
// 断开mqtt连接
disconnect();
// 发送mqtt消息
send();
/*
* 添加监听
* device_id: 需要监听的设备
* message_code: 需要监听的消息code
* page: 在哪个页面监听
* callback: 监听到数据时的回调函数
* */
subscribe(device_id: string, message_code: string | number, page: string, callback: () => any);
// 解除监听，参数参考subscribe
unsubscribe(device_id: string, message_code: string | number, page: string);
}
// 重连次数
let reconnect_count = 0;
// MQTT处理
class MQTT implements MQTT_interface {
public mqtt
public url: string = ''
public username: string = ''
public password: string = ''
public useSSL: boolean = true
public keepAliveInterval: number = 10;
constructor() {
}
setConnectOptions({url, username, password, useSSL, keepAliveInterval}
: { url?: string, username?: string, password?: string, useSSL?: boolean, keepAliveInterval?: number }
) {
if (url)
this.url = url;
if (username)
this.username = username;
if (password)
this.password = password;
if (useSSL)
this.useSSL = useSSL;
if (keepAliveInterval)
this.keepAliveInterval = keepAliveInterval
}
connect() {
// 模拟发送消息
setInterval(() => {
let message: { topic: string, payloadString: string } = {
topic: 'topic/device_id_1',
payloadString: JSON.stringify({f: Math.floor(Math.random() * 10), p: Math.floor(Math.random() * 100)})
}
onMqttMessageArrived(message)
}, 1.5 * 1000)
/*
this.mqtt = new Paho.Client(this.url, this.password)
this.mqtt.onConnectionLost = this.reconnect();
this.mqtt.onMessageArrived = onMqttMessageArrived;
return new Promise(resolve => {
this.mqtt.connect({
userName:this.username,
password:this.password,
useSSL:this.useSSL,
keepAliveInterval:this.keepAliveInterval,
onSuccess(){
reconnect_count = 0;
resolve(true);
},
onFailure(){
this.reconnect();
}
})
})
*/
}
reconnect() {
reconnect_count++;
setTimeout(() => {
this.connect();
}, reconnect_count * .5)
}
disconnect(): boolean {
return true
}
send() {
}
subscribe(device_id: string, message_code: string | number, page: string, callback: (message) => any) {
if (!(device_id in SUBSCRIBER))
SUBSCRIBER[device_id] = {}
if (!(message_code in SUBSCRIBER[device_id]))
SUBSCRIBER[device_id][message_code] = []
let is_existed = SUBSCRIBER[device_id][message_code].some(item => item.page === page)
if (is_existed)
SUBSCRIBER[device_id][message_code] = SUBSCRIBER[device_id][message_code].map(item => item.page === page ? {
...item,
callback
} : item)
else
SUBSCRIBER[device_id][message_code].push({page, callback})
return SUBSCRIBER
}
unsubscribe(device_id: string, message_code: string | number, page: string) {
if ((device_id in SUBSCRIBER) && (message_code in SUBSCRIBER[device_id])) {
SUBSCRIBER[device_id][message_code] = SUBSCRIBER[device_id][message_code].filter(item => item.page !== page)
if (SUBSCRIBER[device_id][message_code].length === 0) {
delete SUBSCRIBER[device_id][message_code]
}
}
return SUBSCRIBER
}
}
建立连接
// 建立mqtt连接
let mqtt = new MQTT();
mqtt.setConnectOptions({url: '', username: '', password:''})
mqtt.connect()
消息订阅与取消
// 在不同页面/组件内，订阅mqtt消息
mqtt.subscribe('device_id_1', 1, 'page_1', message => {
console.log('callback', 'device_id_1-page_1', message)
})
mqtt.subscribe('device_id_1', 1, 'page_2', message => {
console.log('callback', 'device_id_1-page_2', message)
})
mqtt.subscribe('device_id_1', 2, 'page_1', message => {
console.log('callback', 'device_id_1-page_1', message)
})
mqtt.subscribe('device_id_1', 3, 'page_1', message => {
console.log('callback', 'device_id_1-page_1', message)
})
// 取消订阅某条消息（退出页面，取消不需要的订阅）
mqtt.unsubscribe('device_id_1', 2, 'page_1')