前端WebSocket封装

参考：https://www.jianshu.com/p/a4eacaf8de17

一、只有单个长链接，不要求保活

class WebSocketClass {
  constructor() {
    this.instance = null;
    this.connect();
  }
  static getInstance() {
    if (!this.instance) {
      this.instance = new WebSocketClass();
    }
    return this.instance;
  }

  connect() {
    this.ws = new WebSocket('ws://xxxxxx');
    this.ws.onopen = e => {
      this.status = 'open';
      console.log(`${name}连接成功`, e);
    };
  }

  getMessage() {
    this.ws.onmessage = e => {
      console.log(e.data);
      return e.data;
    };
  }

   close() {
    this.ws.send('close');
    this.ws.close();
    console.log('close');
  }
}

export default new WebSocketClass();

二、多个长链接共存

class WebSocketClass {
  constructor(name) {
    this.connect(name);
  }

  connect(name) {
    this.ws = new WebSocket(name);
    this.ws.onopen = e => {
      this.status = 'open';
      console.log(`${name}连接成功`, e);
    };
  }

  getMessage() {
    this.ws.onmessage = e => {
      console.log(e.data);
      return e.data;
    };
  }

  close() {
    this.ws.send('close');
    this.ws.close();
    console.log('close');
  }
}

export default WebSocketClass;

关闭：这种情况就无法跨页面关闭了，只能在哪里开的在哪里关，不然是关不了的，拿不到创建的时候的ws长链接对象。

三、保活

保活的原理-->心跳，前端每隔一段时间发送一段约定好的message给后端，后端收到后返回一段约定好的message给前端，如果多久没收到前端就调用重连方法进行重连。

import { message } from 'antd';

class WebSocketClass {
  constructor() {
    this.instance = null;
    this.connect();
  }
  static getInstance() {
    if (!this.instance) {
      this.instance = new WebSocketClass();
    }
    return this.instance;
  }

  connect() {
    this.ws = new WebSocket('ws://xxxx');
    this.ws.onopen = e => {
      this.status = 'open';
      message.info('连接成功');
      console.log(`连接成功`, e);
      this.heartCheck();
      this.getMessage();
    };
  }

  heartCheck() {
    // 心跳机制的时间可以自己与后端约定
    this.pingPong = 'ping'; // ws的心跳机制状态值
    this.pingInterval = setInterval(() => {
      if (this.ws.readyState === 1) {
        // 检查ws为链接状态 才可发送
        this.ws.send('ping'); // 客户端发送ping
      }
    }, 10000);
    this.pongInterval = setInterval(() => {
      if (this.pingPong === 'ping') {
        this.closeHandle('pingPong没有改变为pong'); // 没有返回pong 重启webSocket
      }
      // 重置为ping 若下一次 ping 发送失败 或者pong返回失败(pingPong不会改成pong)，将重启
      console.log('返回pong');
      this.pingPong = 'ping';
    }, 20000);
  }

  closeHandle(e = 'err') {
    // 因为webSocket并不稳定，规定只能手动关闭(调closeMyself方法)，否则就重连
    if (this.status !== 'close') {
      console.log(`断开，重连websocket`, e);
      if (this.pingInterval !== undefined && this.pongInterval !== undefined) {
        // 清除定时器
        clearInterval(this.pingInterval);
        clearInterval(this.pongInterval);
      }
      this.connect(); // 重连
    } else {
      console.log(`websocket手动关闭,或者正在连接`);
    }
  }

  getMessage() {
    this.ws.onmessage = e => {
      if (e.data === 'pong') {
        this.pingPong = 'pong'; // 服务器端返回pong,修改pingPong的状态
      } else {
        message.info(e.data);
      }
      console.log(e.data);
      return e.data;
    };
  }

  close() {
    clearInterval(this.pingInterval);
    clearInterval(this.pongInterval);
    this.status = 'close';
    this.ws.send('close');
    this.ws.close();
    message.info('已断开连接');
    console.log('close');
  }
}

export default new WebSocketClass();