使用mpvue 开发小程序过程中 简单介绍一下微信小程序蓝牙连接过程

在蓝牙连接的过程中部分api需要加定时器延时1秒到2秒左右再执行，原因为何不知道，小程序有这样的要求

1.首先是要初始化蓝牙：openBluetoothAdapter()

if (wx.openBluetoothAdapter) {
 wx.openBluetoothAdapter({
 success: function(res) {
 /* 获取本机的蓝牙状态 */
 setTimeout(() => {
 getBluetoothAdapterState()
 }, 1000)
 },
 fail: function(err) {
 // 初始化失败
 }
 })
} else {
}

2.检测本机蓝牙是否可用：

要在上述的初始化蓝牙成功之后回调里调用

getBluetoothAdapterState() {
 var that = this;
 that.toastTitle = '检查蓝牙状态'
 wx.getBluetoothAdapterState({
 success: function(res) {
 startBluetoothDevicesDiscovery()
 },
 fail(res) {
 console.log(res)
 }
 })
}

3. 开始搜索蓝牙设备：

startBluetoothDevicesDiscovery() {
 var that = this;
 setTimeout(() => {
 wx.startBluetoothDevicesDiscovery({
 success: function(res) {
 /* 获取蓝牙设备列表 */
 that.getBluetoothDevices()
 },
 fail(res) {
 }
 })
 }, 1000)
}

4. 获取搜索到的蓝牙设备列表

/ that.deviceName 是获取到的蓝牙设备的名称， 因为蓝牙设备在安卓和苹果手机上搜到的蓝牙地址显示是不一样的，所以根据设备名称匹配蓝牙/

getBluetoothDevices() {
 var that = this;
 setTimeout(() => {
 wx.getBluetoothDevices({
 services: [],
 allowDuplicatesKey: false,
 interval: 0,
 success: function(res) {
 if (res.devices.length > 0) {
 if (JSON.stringify(res.devices).indexOf(that.deviceName) !== -1) {
 for (let i = 0; i < res.devices.length; i++) {
 if (that.deviceName === res.devices[i].name) {
 /* 根据指定的蓝牙设备名称匹配到deviceId */
 that.deviceId = that.devices[i].deviceId;
 setTimeout(() => {
 that.connectTO();
 }, 2000);
 };
 };
 } else {
 }
 } else {
 }
 },
 fail(res) {
 console.log(res, '获取蓝牙设备列表失败=====')
 }
 })
 }, 2000)
},

5.连接蓝牙

匹配到的蓝牙设备ID 发送连接蓝牙的请求， 连接成功之后 应该断开蓝牙搜索的api，然后去获取所连接蓝牙设备的service服务

connectTO() {
 wx.createBLEConnection({
 deviceId: deviceId,
 success: function(res) {
 that.connectedDeviceId = deviceId;
 /* 4.获取连接设备的service服务 */
 that.getBLEDeviceServices();
 wx.stopBluetoothDevicesDiscovery({
 success: function(res) {
 console.log(res, '停止搜索')
 },
 fail(res) {
 }
 })
 },
 fail: function(res) {
 }
 })
}

6. 获取蓝牙设备的service服务,获取的serviceId有多个要试着连接最终确定哪个是稳定版本的service 获取服务完后获取设备特征值

getBLEDeviceServices() {
 setTimeout(() => {
 wx.getBLEDeviceServices({
 deviceId: that.connectedDeviceId,
 success: function(res) {
 that.services = res.services
 /* 获取连接设备的所有特征值 */
 that.getBLEDeviceCharacteristics()
 },
 fail: (res) => {
 }
 })
 }, 2000)
},

7.获取蓝牙设备特征值

获取到的特征值有多个，最后要用的事能读，能写，能监听的那个值的uuid作为特征值id，

 getBLEDeviceCharacteristics() {
 setTimeout(() => {
 wx.getBLEDeviceCharacteristics({
 deviceId: connectedDeviceId,
 serviceId: services[2].uuid,
 success: function(res) {
 for (var i = 0; i < res.characteristics.length; i++) {
 if ((res.characteristics[i].properties.notify || res.characteristics[i].properties.indicate) &&
 (res.characteristics[i].properties.read && res.characteristics[i].properties.write)) {
 console.log(res.characteristics[i].uuid, '蓝牙特征值 ==========')
 /* 获取蓝牙特征值 */
 that.notifyCharacteristicsId = res.characteristics[i].uuid
 // 启用低功耗蓝牙设备特征值变化时的 notify 功能
 that.notifyBLECharacteristicValueChange()
 }
 }
 },
 fail: function(res) {
 }
 })
 }, 1000)
 },

8.启动notify 蓝牙监听功能 然后使用 wx.onBLECharacteristicValueChange用来监听蓝牙设备传递数据

接收到的数据和发送的数据必须是二级制数据， 页面展示的时候需要进行转换

 notifyBLECharacteristicValueChange() { // 启用低功耗蓝牙设备特征值变化时的 notify 功能
 var that = this;
 console.log('6.启用低功耗蓝牙设备特征值变化时的 notify 功能')
 wx.notifyBLECharacteristicValueChange({
 state: true,
 deviceId: that.connectedDeviceId,
 serviceId: that.notifyServicweId,
 characteristicId: that.notifyCharacteristicsId,
 complete(res) {
 /*用来监听手机蓝牙设备的数据变化*/
 wx.onBLECharacteristicValueChange(function(res) {
 /**/
 that.balanceData += that.buf2string(res.value)
 that.hexstr += that.receiveData(res.value)
 })
 },
 fail(res) {
 console.log(res, '启用低功耗蓝牙设备监听失败')
 that.measuringTip(res)
 }
 })
 },
 /*转换成需要的格式*/
 buf2string(buffer) {
 var arr = Array.prototype.map.call(new Uint8Array(buffer), x => x)
 return arr.map((char, i) => {
 return String.fromCharCode(char);
 }).join('');
 },
 receiveData(buf) {
 return this.hexCharCodeToStr(this.ab2hex(buf))
 },
 /*转成二进制*/
 ab2hex (buffer) {
 var hexArr = Array.prototype.map.call(
 new Uint8Array(buffer), function (bit) {
 return ('00' + bit.toString(16)).slice(-2)
 }
 )
 return hexArr.join('')
 },
 /*转成可展会的文字*/
 hexCharCodeToStr(hexCharCodeStr) {
 var trimedStr = hexCharCodeStr.trim();
 var rawStr = trimedStr.substr(0, 2).toLowerCase() === '0x' ? trimedStr.substr(2) : trimedStr;
 var len = rawStr.length;
 var curCharCode;
 var resultStr = [];
 for (var i = 0; i < len; i = i + 2) {
 curCharCode = parseInt(rawStr.substr(i, 2), 16);
 resultStr.push(String.fromCharCode(curCharCode));
 }
 return resultStr.join('');
 },

向蓝牙设备发送数据

sendData(str) {
 let that = this;
 let dataBuffer = new ArrayBuffer(str.length)
 let dataView = new DataView(dataBuffer)
 for (var i = 0; i < str.length; i++) {
 dataView.setUint8(i, str.charAt(i).charCodeAt())
 }
 let dataHex = that.ab2hex(dataBuffer);
 this.writeDatas = that.hexCharCodeToStr(dataHex);
 wx.writeBLECharacteristicValue({
 deviceId: that.connectedDeviceId,
 serviceId: that.notifyServicweId,
 characteristicId: that.notifyCharacteristicsId,
 value: dataBuffer,
 success: function (res) {
 console.log('发送的数据：' + that.writeDatas)
 console.log('message发送成功')
 },
 fail: function (res) {
 },
 complete: function (res) {
 }
 })
 },

当不需要连接蓝牙了后就要关闭蓝牙，并关闭蓝牙模块

 // 断开设备连接
closeConnect() {
 if (that.connectedDeviceId) {
 wx.closeBLEConnection({
 deviceId: that.connectedDeviceId,
 success: function(res) {
 that.closeBluetoothAdapter()
 },
 fail(res) {
 }
 })
 } else {
 that.closeBluetoothAdapter()
 }
},
// 关闭蓝牙模块
closeBluetoothAdapter() {
 wx.closeBluetoothAdapter({
 success: function(res) {
 },
 fail: function(err) {
 }
 })
},

在向蓝牙设备传递数据和接收数据的过程中，并未使用到read的API 不知道有没有潜在的问题，目前线上运行为发现任何的问题

今天的蓝牙使用心得到此结束，谢谢