wx.previewImage({
      urls: urlList //urlList是数组
})

var sotk = null;
var socketOpen = false;
var wsbasePath = "ws://开发者服务器 wss 接口地址/";

//开始webSocket
  webSocketStart(e){
    sotk = wx.connectSocket({
      url: wsbasePath,
      header: { 'content-type': 'application/x-www-form-urlencoded' },
      method: "POST",
      success: res => {
        console.log('小程序连接成功：', res);
      },
      fail: err => {
        console.log('出现错误啦！！' + err);
        wx.showToast({
          title: '网络异常！',
        })
      }
    })

    this.webSokcketMethods();

  },

//监听指令
  webSokcketMethods(e){
    let that = this;
    sotk.onOpen(res => {
      socketOpen = true;
      console.log('监听 WebSocket 连接打开事件。', res);
    })
    sotk.onClose(onClose => {
      console.log('监听 WebSocket 连接关闭事件。', onClose)
      socketOpen = false;
    })
    sotk.onError(onError => {
      console.log('监听 WebSocket 错误。错误信息', onError)
      socketOpen = false
    })

    sotk.onMessage(onMessage => {
      var data =http://www.wxapp-union.com/ JSON.parse(onMessage.data);
      console.log('监听WebSocket接受到服务器的消息事件。服务器返回的消息',data);
     
    })
   
  },

//发送消息
  sendSocketMessage(msg) {
    let that = this;
    if (socketOpen){
      console.log('通过 WebSocket 连接发送数据', JSON.stringify(msg))
      sotk.send({
        data: JSON.stringify(msg)
      }, function (res) {
        console.log('已发送', res)
      })
    }
    
  },
 //关闭连接
  closeWebsocket(str){
    if (socketOpen) {
      sotk.close(
        {
          code: "1000",
          reason: str,
          success: function () {
            console.log("成功关闭websocket连接");
          }
        }
      )
    }
  }

var mqtt = require('utils/mqtt.min.js');
var client = null;
var connect = function(id) {
    return new Promise((resolve,reject)=>{
            const options = {
                connectTimeout: 4000, // 超时时间
                clientId: 'wx_' + parseInt(Math.random() * 100 + 800, 10),
                port:8084
            }

            client = mqtt.connect('wxs://xxx', options)

            client.on('reconnect', (error) => {
                console.log('正在重连:', error)
            })

            client.on('error', (error) => {
                console.log('连接失败:', error)
            })

            let that = this;
            client.on('connect', (e) => {
                console.log('成功连接服务器')
                //订阅主题
                client.subscribe(['主题1'+id, '主题2'+id], {
                    qos: 1
                }, function (err) {
                    if (!err) {
                        console.log("订阅成功")
                        resolve(client)
                    }
                })
            })
    })
}

client.on('message', function (topic, message, packet) {
       console.log(packet)
})