解决办法 为复制一份this的指向到变量中，这样在函数执行过程中虽然this改变了，但是that还是指向之前的对象。
大家知道this是指当前对象，只是一个指针，真正的对象存放在堆内存中，this的指向在程序执行过程中会变化，因此如果需要在函数中使用全局数据需要合适地将this复制到变量中。
this作用域分析：
1.在Page({})里面，this关键字指代Page({})整个对象
2.因此可以通过this关键字访问或者重新设置Page({})里data的变量
3.然而在loadData函数中使用了wx.request({})API这个方法导致在wx.request({})里没办法使用this来获取Page({})对象
4.虽然在wx.request({})里没法使用this获取Page({})对象，但是可以在wx.request({})外面先把this存在某个变量中，所以就有了 var that =this 这个声明。此时that指代Page({})整个对象，这样子就可以在wx.request({})里使用that访问或者重新设置Page({})里data的变量
//index.js//获取应用实例
const app = getApp()
const util = require('../../utils/util.js')
const bletool = require('../../utils/bletool.js')
Page({
data: {
// lists: [{ 'order_no': '1111', 'car_no': '321', 'car_type': '尚好捷', 'order_date': '2018-01-02 08:00', 'order_money': '16.00', 'order_time': '4' }],
car_no: '',
order_no: '',
lists: [],
serviceId: '',//592B3370-3900-9A71-4535-35D4212D2837
serviceMac: '',//C9:9B:4C:E7:DE:10
service_psd: '',//855525B837253705595800000329
service_uuid: '',
deviceId:'',
characteristics:[] //特征值
},
onLoad: function (options) {
this.initBle()
},
onReady: function () {
// 页面渲染完成
},
onShow: function () {
if (app.globalData.car_no.length>0){
this.getDeviceInfo()
}
},
onHide: function () {
// 页面隐藏
},
onUnload: function () {
// 页面关闭
app.globalData.car_no=''
},
//蓝牙相关
//初始化蓝牙
initBle: function () {
var that = this
wx.onBluetoothAdapterStateChange(function (res) {
console.log('adapterState changed, now is', res)
app.globalData.ble_state = res.available
if (res.available) {
that.initBle()
} else {
util.showToast('手机蓝牙已关闭')
app.globalData.ble_isonnectting = false
}
})
//打开蓝牙适配器
wx.openBluetoothAdapter({
success: function (res) {
console.log('打开蓝牙适配器成功')
that.getBluetoothAdapterState()
app.globalData.ble_state = true
that.onBluetoothDeviceFound()
},
fail: function (res) {
// fail
console.log(res)
util.showToast('请打开手机蓝牙')
},
complete: function (res) {
// complete
}
})
},
onBluetoothDeviceFound:function(){
var that = this
//监听扫描
wx.onBluetoothDeviceFound(function (res) {
// res电脑模拟器返回的为数组；手机返回的为蓝牙设备对象
console.log('监听搜索新设备：', res)
that.updateBleList([res])
})
},
getBluetoothAdapterState: function () {
var that = this
wx.getBluetoothAdapterState({
success: function (res) {
var available = res.available
var discovering = res.discovering
if (!available) {
util.showToast('蓝牙不可用')
} else {
if (!discovering) {
// that.startBluetoothDevicesDiscovery()
}
}
}
})
},
startBluetoothDevicesDiscovery: function () {
var that = this
var services = []
services.push(this.data.serviceId)
wx.showLoading({
title: '设备搜索中'
})
setTimeout(function () {
wx.hideLoading()
if (app.globalData.deviceId.length==0){
util.showModal('设备搜索失败，请重试')
}
}, 10000)
if(bletool.isIOS()){
wx.startBluetoothDevicesDiscovery({
services: services,
allowDuplicatesKey: true,
success: function (res) {
console.log('ios搜索成功')
console.log(res)
},
fail: function (err) {
console.log(err)
}
})
}else{
wx.startBluetoothDevicesDiscovery({
// services: services,
allowDuplicatesKey: true,
success: function (res) {
console.log('Android搜索成功')
console.log(res)
},
fail: function (err) {
console.log(err)
wx.hideLoading()
that.startBluetoothDevicesDiscovery()
// that.getBluetoothAdapterState()
util.showToast('搜索失败')
}
})
}
},
startConnectDevices: function (ltype, array) {
var that = this
clearTimeout(that.getConnectedTimer)
that.getConnectedTimer = null
wx.stopBluetoothDevicesDiscovery({
success: function (res) {
// success
}
})
app.globalData.ble_isonnectting = true
console.log('连接前：'+that.deviceId)
wx.createBLEConnection({
deviceId: that.deviceId,
success: function (res) {
if (res.errCode == 0) {
console.log('连接成功：')
that.getService(that.deviceId)
}
},
fail: function (err) {
console.log('连接失败：', err)
wx.hideLoading()
util.showModal('设备连接失败，请重试')
// if (ltype == 'loop') {
// that.connectDeviceIndex += 1
// that.loopConnect(array)
// } else {
// that.startBluetoothDevicesDiscovery()
// that.getConnectedBluetoothDevices()
// }
app.globalData.ble_isonnectting = false
},
complete: function () {
}
})
},
getService: function (deviceId) {
var that = this
// 监听蓝牙连接
wx.onBLEConnectionStateChange(function (res) {
console.log(res)
app.globalData.ble_isonnectting = res.connected
if (!res.connected) {
util.showToast('连接断开')
}
})
// 获取蓝牙设备service值
wx.getBLEDeviceServices({
deviceId: deviceId,
success: function (res) {
console.log('获取蓝牙设备service值')
console.log(res)
that.getCharacter(deviceId, res.services)
}
})
},
getCharacter: function (deviceId, services) {
var that = this
services.forEach(function (value, index, array) {
if (value.isPrimary) {
that.setData({
service_uuid: value.uuid,
deviceId: deviceId
})
app.globalData.service_uuid= value.uuid
app.globalData.deviceId=deviceId
}
})
//监听通知
wx.onBLECharacteristicValueChange(function (res) {
// callback
console.log('value change', res)
const hex = bletool.buf2char(res.value)
console.log('返回的数据：', hex)
//配对密码
if (hex.indexOf('855800000106') != -1) {
wx.hideLoading()
var charact_write = that.data.characteristics[1]
bletool.writeDataToDevice(that.data.deviceId, that.data.service_uuid, charact_write, that.data.service_psd)
wx.showToast({
title: '设备已连接',
icon: 'success',
duration: 3000
})
setTimeout(function () {
bletool.writeDataToDevice(that.data.deviceId, that.data.service_uuid, charact_write, '235525B837253705590400000273')
}, 2000)
} else if (hex.indexOf('23040000') != -1) {
//启动成功
that.starRenting()
}
})
wx.getBLEDeviceCharacteristics({
deviceId: deviceId,
serviceId: that.getServiceUUID(),
success: function (res) {
wx.getBLEDeviceCharacteristics({
deviceId: deviceId,
serviceId: that.getServiceUUID(),
success: function (res) {
console.log('特征', res)
that.setData({
characteristics:res.characteristics
})
app.globalData.characteristics = res.characteristics
var charact_read = res.characteristics[0]
},
loopConnect: function (devicesId) {
var that = this
var listLen = devicesId.length
if (devicesId[this.connectDeviceIndex]) {
this.deviceId = devicesId[this.connectDeviceIndex]
this.startConnectDevices('loop', devicesId)
} else {
console.log('已配对的设备小程序蓝牙连接失败')
that.startBluetoothDevicesDiscovery()
that.getConnectedBluetoothDevices()
}
},
//更新数据 devices为数组类型
updateBleList: function (devices) {
console.log('设备数据：',devices)
var newData = this.data.bleList
var that = this
var tempDevice = null
for (var i = 0i <devices.lengthi++) {
//ios设备
if (devices[i].devices != null) {
if (devices[i].devices.length >0) {
tempDevice = devices[i].devices[0]
}
else {
continue
}
}
//安卓
else {
tempDevice = devices[i]
}
if (!this.isExist(tempDevice)) {
newData.push(tempDevice)
}
}
console.log('数据：')
console.log(newData)
this.setData({
bleList: newData
})
if (!app.globalData.ble_isonnectting) {
var that = this
this.data.bleList.forEach(function (value, index, array) {
//找到对应id的设备，ios判断服务id安卓判断mac地址
var deviceId = value['deviceId']
if(bletool.isIOS()){
let advertisServiceUUID = value['advertisServiceUUIDs'][0]
if (advertisServiceUUID == that.data.serviceId.toUpperCase()){
that.deviceId = deviceId
console.log(that.deviceId)
that.startConnectDevices()
}
}else{
if (deviceId == that.data.serviceMac) {
that.deviceId = deviceId
console.log(that.deviceId)
that.startConnectDevices()
}
}
})
}
},
//是否已存在 存在返回true 否则false
isExist: function (device) {
var tempData = this.data.bleList
for (var i = 0i <tempData.lengthi++) {
if (tempData[i].deviceId == device.deviceId) {
return true
}
}
return false
},
//服务uuid
getServiceUUID: function () {
return bletool.stringTransition(this.data.service_uuid)
},
getDeviceInfo: function () {
let car_no = app.globalData.car_no
var that = this
wx.request({
url: app.globalData.serverURL + '?c=car&a=getDeviceInfo&open_id=' + app.globalData.open_id + '&car_no=' + car_no,
method: 'GET', // OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, CONNECT
header: { 'content-type': 'application/json' }, // 设置请求的 header
success: function (res) {
// success
var data = res.data
console.log(data)
if (data.result == 1) {
app.globalData.serviceId = data.data.service_id
app.globalData.serviceMac = data.data.service_mac,
app.globalData.service_psd = '85' + data.data.service_psd + '5800000329'
that.setData({
serviceId: data.data.service_id,
serviceMac: data.data.service_mac,
service_psd: '85' + data.data.service_psd+'5800000329',
})
app.startBluetoothDevicesDiscovery()
// that.onBLECharacteristicValueChange()
} else {
util.showModal(data.msg)
}
},
fail: function () {
},
complete: function () {
// complete
}
})
},
})
微信小程序 setData常用错误解决办法：
1、微信小程序中，在wx.request({})方法调用成功或者失败之后，有时候会需要获取页面初始化数据data的情况，这个时候，如果使用，this.data来获取，会出现获取不到的情况，调试页面也会报undefiend。
原因是，在javascript中，this代表着当前对象，会随着程序的执行过程中的上下文改变，在wx.request({})方法的回调函数中，对象已经发生改变，所以已经不是wx.request({})方法对象了，data属性也不存在了。官方的解决办法是，复制一份当前的对象，如下：
var that=this//把this对象复制到临时变量that。在success回调函数中使用that.data就能获取到数据了。
2、下面就是修改代码，必须setData一下，不然地图不会刷新。
markers: { iconPath:
"/picture/bike.png", id: 0, latitude: 23.099994, longitude:
113.324520, width: 50, height: 50 }
for(var i = 0i <res.data.lengthi++){ //
that.data.markers[i].id=i // mark.id=i var param =
{} var string = "markers["+i+"].id" param[string] =
res.data[i].Bike_id that.setData(param)
var string="markers["+i+"].iconPath" param[string]
="/picture/bike.png" that.setData(param) var
string = "markers["+i+"].latitude" param[string] =
res.data[i].BIKE_latitude that.setData(param)
var string = "markers["+i+"].longitude"
param[string] = res.data[i].BIKE_longitude
that.setData(param) var string =
"markers["+i+"].width" param[string] = 50
that.setData(param) var string = "markers["+i+"].height"
param[string] = 50 that.setData(param)
/* that.setData({ markers:[{ iconPath:
"/picture/bike.png", id: 0, latitude: 23.099994, longitude:
113.324520, width: 50, height: 50 }] })*/
} // console.log(res.data[1]) var
markk=that.data.markers that.setData({markers:markk})
小程序setData()设置，百度找到： http://www.jb51.net/article/111691.htm
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