Native WebSokcet implementation method for disconnection reconnection and data splicing

WebSocket protocol is a new protocol of HTML5. It implements full-duplex communication between the browser and the server. This article mainly shares with you the WeChat applet using native WebSokcet to realize disconnection reconnection and data splicing. I hope it can help everyone.

1. Description

1. The native WebSokcet of the mini program does not have a disconnection and reconnection mechanism. This is its shortcoming.

2. The new version library of the mini program already supports multiple WebSokcet connections.

Official description: Before Basic Library 1.7.0, a WeChat applet could only have one WebSocket connection at the same time. If a WebSocket connection currently exists, the connection will be automatically closed and a new WebSocket connection will be created. Basic library version 1.7.0 and later supports multiple WebSokcet connections, and each successful call to wx.connectSocket will return a new SocketTask.

Official document address: https://mp.weixin.qq.com/debug/wxadoc/dev/api/network-socket.html#wxclosesocket

2. Practical examples:

First you need the socket address url: let url = 'wss://http://xxx.xxx.com/?xxx=xxx'

Note: 1. Add the socket in the mini program management background The port cannot appear in the domain name; 2. If appID is used, the protocol must be wss; 3. The port mapped by the socket server only supports 80 and 443, which is the same as the official account.

Next examples:

1, socket.js

const app = getApp();
let url = 'wss://xxx.xxx.com/?xxx=xxx'
export const connect = function (cb) { // 定义一个方法
  wx.connectSocket({ // 创建一个 WebSocket 连接
      url: url,
      fail (err) {
if (err) {
              console.log('%cWebSocket连接失败', 'color:red', err)
              app.globalData.socketConnectFail = true // 定义一个全局变量，当链接失败时改变变量的值
}
}
})

  wx.onSocketOpen(function (res) { // 监听WebSocket连接打开事件。
      console.log('WebSocket打开成功');
      wx.sendSocketMessage({ // 通过 WebSocket 连接发送数据，需要先 wx.connectSocket，并在 wx.onSocketOpen 回调之后才能发送。
          data: String2Base64(), // 用于订阅的参数，视具体情况而定
          success (data) {
              console.log('WebSocket发送消息:', data.errMsg)
},
          fail (err) {
              console.log('Err', err)
}
})

})

  wx.onSocketMessage(function (res) { // 监听WebSocket接受到服务器的消息事件。
      console.log('WebSocket接收到消息:', ArryBuffer2Json(res.data));
      cb(ArryBuffer2Json(res.data)); // 将接收到的消息进行回调，如果是ArryBuffer，需要进行转换
})

  wx.onSocketError(function (res) { // 监听WebSocket错误。
      console.log('WebSocket连接打开失败')
})

  wx.onSocketClose(function (res) { // 监听WebSocket关闭。
      console.log('WebSocket关闭');
})
};

function ArryBuffer2Json (data) { // ArryBuffer转换成Json
try {
var encodedString = String.fromCharCode.apply(null, new Uint8Array(data));
var decodedString = decodeURIComponent(atob(encodedString));
return JSON.parse(decodedString);
} catch (err) {
      console.log(err);
return false;
}
}


function String2Base64 () { // 用于订阅的参数，视具体情况而定
var packet = {};
  packet["cmd"] = "subscribe";
  packet["reqNo"] = "" + new Date().getTime();
  packet["params"] = {token: token, channelId: 'xcx', columnIds: "1"};
return stringToUint(JSON.stringify(packet))
}

function stringToUint (string) {
var string = base64_encode(encodeURIComponent(string)),
      charList = string.split(''),
      uintArray = [];
for (var i = 0; i < charList.length; i++) {
      uintArray.push(charList[i].charCodeAt(0));
}
return new Uint8Array(uintArray);
}

function base64_encode (str) { // base64转码
var c1, c2, c3;
var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var i = 0, len = str.length, string = &#39;&#39;;

while (i < len) {
      c1 = str.charCodeAt(i++) & 0xff;
if (i == len) {
string += base64EncodeChars.charAt(c1 >> 2);
string += base64EncodeChars.charAt((c1 & 0x3) << 4);
string += "==";
break;
}
      c2 = str.charCodeAt(i++);
if (i == len) {
string += base64EncodeChars.charAt(c1 >> 2);
string += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
string += base64EncodeChars.charAt((c2 & 0xF) << 2);
string += "=";
break;
}
      c3 = str.charCodeAt(i++);
string += base64EncodeChars.charAt(c1 >> 2);
string += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
string += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));
string += base64EncodeChars.charAt(c3 & 0x3F)
}
return string
}

2, index.js

let openSocket = require('../../config/socket.js');
const app = getApp();
data: {
  motto: 'Hello World',
  articleData: []
},
onLoad: function () {
let that = this;
  openSocket.connect(function (data) { // WebSocket初始化连接
let result = data.data
if (result) {
          that.setData({articleData: [result].concat(that.data.articleData)}) // 将获得的socket推送消息拼接到当前文章列表的最前面
}
});
if (app.globalData.socketConnectFail) { // WebSocket断线重连
      setInterval(() => {
          openSocket.connect(function (data) {
let result = data.data
if (result) {
                  that.setData({articleData: [result].concat(that.data.articleData)})
}
});
}, 1000)
}
}

3、app.js
globalData: {  socketConnectFail: false}

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