angular + express 实现websocket通信

最近需要实现一个功能，后端通过TCP协议连接雷达硬件的控制器，前端通过websocket连接后端，当控制器触发消息的时候，把信息通知给所以前端；

第一个思路是单独写一个后端服务用来实现websocket，调试成功了，后来又发现一个插件express-ws，于是决定改变思路，研究了下，最终代码如下，希望帮助更多的朋友，不再害怕websocket

首先写一个前端websocket服务。这里我选择放弃单例模式，采用谁调用谁负责销毁的思路

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
import { LoginService } from '../login/login.service';
import { environment } from 'src/environments/environment';

export class WsConnect {
  ws!:WebSocket;
  sendWs!:(msg:string)=>void;
  closeWs!:()=>void;
  result!:Observable<any>
}
@Injectable({providedIn:"root"})
export class WebsocketService {

  origin = window.location.origin.replace('http', 'ws');

  constructor(
    private loginService: LoginService
  ) { }

  getUrl(path:string){
    return `${this.origin}${path}`;
  }
  connect(path:string):WsConnect{
    let url = this.getUrl(path);
    let ws = new WebSocket(url, this.loginService.userInfo.jwt);  // 在这里放入jwt信息，目前没有找到其它地方可以放。有些网友建议先放入地址，然后在nginx里重新放入header，我觉得不够接地气
    return {
      ws,
      sendWs:function(message:string){
        ws.send(message);
      },
      closeWs:function(){
        ws.close();
      },
      result:new Observable(
        observer => {
            ws.onmessage = (event) => { observer.next(event.data)};//接收数据
            ws.onerror =  (event) => {console.log("ws连接错误：",event);observer.error(event)};//发生错误
            ws.onclose =  (event) => {console.log("ws连接断开：",event); observer.complete() };//结束事件
            ws.onopen =  (event) => { console.log("ws连接成功：",event);};//结束事件
        }
      )
    }
  }
}

然后在组件里调用

import { Component, OnDestroy, OnInit } from '@angular/core';

import { WebsocketService, WsConnect } from '../utils/websocket-client.service';
@Component({
  selector: 'app-car-measure',
  templateUrl: './car-measure.component.html',
  styleUrls: ['./car-measure.component.scss']
})
export class CarMeasureComponent implements OnInit , OnDestroy{
  connect!:WsConnect;
  constructor(public wsService:WebsocketService) { }

  ngOnInit() {
    this.connectServer();
  }

  connectServer(){
    this.connect = this.wsService.connect('/websocket/carMeasure')
    this.connect.result.subscribe(
        (data:any) => {   //接收到服务端发来的消息
          console.log("服务器消息：",data);
          setTimeout(() => {
            this.connect.sendWs("这是从客户端发出的消息");
          }, 5000);
        }
    )
  }

  ngOnDestroy() {
    this.connect.closeWs(); // 这个方法时把整个ws销毁，而不是取消订阅哦，所以有需要的同学可以考虑取消订阅的方案
  }
}

后端引入express-ws,封装一个可调用的文件，部分代码借鉴了网上的代码，做了一些改善

//websocket.js
const express = require('express');
const router = express.Router();
const expressWs = require('express-ws')
// 初始化
let WS = null;
// 声明一个通道类
let channels = null;
let pathList = [
    '/websocket/carMeasure',
    '/path2'
]
function initWebSocket(app) {
    WS = expressWs(app) //混入app, wsServer 存储所有已连接实例
    // 创建通道
    channels = new channel(router)
    pathList.forEach(path=>{
        channels.createChannel(path)
        // channels.createChannel('/carMeasure/websocket/carSize')
    })
    app.use(router)
}
// 通道类
class channel {
    router;
    constructor(props) {
        this.router = props;
    }
    createChannel(path) {
        // 建立通道
        this.router.ws( path, (ws, req) => {
            //把自定义信息加入到socket里面取，expressws会自动放入到从WS.getWss().clients，
            // 并且会自动根据活动用户删除或者增加客户端
            ws['wsPath'] = path;
            ws['userId'] = req.userInfo._id;
            ws['roleId'] = req.userInfo.role;
            ws.on('message', (msg) => getMsg(msg, path))
            ws.on('close', (code) => close(code, path))
            ws.on('error', (e) => error(e, path))
        })
    }
}
/**
 *
 * @param {*} msg 消息内容
 * @param {String} from 消息来源
 */
// 监听消息
let getMsg = (msg, from) => {
    console.log(msg, from);
    // SendMsgAll({path:'/path2', data: msg })
}
// 发送消息
let sendMsg = (client, data) => {
    if (!client) return
    client.send(JSON.stringify(data))
}
let close = (code) => {
    console.log('关闭连接', code);
}
let error = (e) => {
    console.log('error: ', e);
}
// 群发
/**
 *
 * @param {String} path 需要发送的用户来源 路由，默认全部
 * @param {*} data 发送的数据
 */
function sendMsgToClients(clients,data){
    clients.forEach((client)=> {
        if (client._readyState == 1) {
            sendMsg(client, data)
        }
    })
}

function sendMsgToAll(data = "") {
    let allClientsList = Array.from(WS.getWss().clients)
    sendMsgToClients(allClientsList,data)
}

function sendMsgToPath(data = "", path = '') {
    let allClientsList = Array.from(WS.getWss().clients).filter((ws)=>ws['wsPath'] == path)
    sendMsgToClients(allClientsList,data)
}
function sendMsgToId(data = "", userId = '') {
    let allClientsList = Array.from(WS.getWss().clients).filter((ws)=>ws['userId'] == userId)
    sendMsgToClients(allClientsList,data)
}
function sendMsgToRole(data = "", roleId = '') {
    let allClientsList = Array.from(WS.getWss().clients).filter((ws)=>ws['roleId'] == roleId)
    sendMsgToClients(allClientsList,data)
}
module.exports = {
    initWebSocket,
    sendMsgToAll,
    sendMsgToPath,
    sendMsgToId,
    sendMsgToRole,
}

然后再app.js里面调用就可以了

const {initWebSocket} = require('./public/utils/websocket')
initWebSocket(app)

其中涉及到了权限验证的问题，也可以直接验证jwt

app.use((req,res,next) => {
  if(!whiteList.some(item =>  req.url.startsWith(item))) {
      let httpJwt= req.headers['jwt'];
      let wsJwt= req.headers['sec-websocket-protocol'];  // 这里验证websocket的身份信息，其它代码
      utils.verifyToken(httpJwt || wsJwt).then(res => {   //utils.verifyToken封装了jwt的验证
          req["userInfo"] = res;                        //放入一些信息，方便后续操作

          next()
      }).catch(e => {
          console.error(e);
          res.status(401).send('invalid token')
      })
  } else {
      next()
  }
})

万事具备，最后一步就是等待硬件设备的触发了，其它tcp客户端的代码就不放出来干扰大家了，就是粗暴的调用即可

var {sendMsgToPath} = require('../public/utils/websocket');

sendMsgToPath(JSON.stringify(result), this.carMeasurePath);   // 注意websocket或者tcp的传输都只能用字符串或者blob

另外注意要配置nginx代理，nginx的配置各位应该都清楚吧，这里就不多说了，注意的是这里有几个可选择的地方，一个是前端，可以把ws服务做成单例，另一个是后端路由其实可以写在http的路由文件里，还有一个是对后端ws client的使用，利用了express-ws自身的方法，当然也可以自己写对象来搜集clients （不太建议）

想了以下还是放出来给小白，这里是proxy.config.json

{
    "/api": {
        "target": "http://localhost:3000",
        "secure": false,
        "logLevel": "debug",
        "changeOrigin": true,
        "pathRewrite": {
            "^/api": "/"
        }
    },
    "/websocket":{
      "target": "http://localhost:3000",
      "secure": false,
      "ws": true
    }
}

毕竟讲究的是手把手把你教会，不会也得会，这里是放入服务器的nginx.cong

worker_processes  1;

events {
    worker_connections  1024;
}

http {
    server {
        listen 80;
        server_name  localhost;
        client_max_body_size 20M;
        underscores_in_headers on;

        include /etc/nginx/mime.types;

        gzip on;
        gzip_static on;
        gzip_min_length 1000;
        gzip_types text/plain text/css application/json application/javascript application/x-javascript text/xml application/xml application/xml+rss text/javascript;

        location  /{
            root  /usr/share/nginx/html;
            index  index.html index.htm;
            try_files $uri $uri/ /index.html;
        }

        location /api {
            rewrite  ^/api/(.*)$ /$1 break;
            proxy_pass http://localhost:3000;

        }
         location /websocket {
            proxy_set_header   X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header   Host      $http_host;
            proxy_set_header X-NginX-Proxy true;
            proxy_pass http://localhost:3000;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
        }
    }
}

最后，祝大家工作顺利,请记住 ‘耳机大神’ 永远陪着你