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为了简化微信小程序环境下的蓝牙接入流程，通过线上正式我的项目一年的运行，发现 BLE 这块 API 许多坑，且难以移植复用，所以将它封装进去进步可维护性以及可移植性。
如何应用
装置 Eventenitter
npm install eventemitter2 --save
引入
在我的项目根目录 utils 文件夹下增加如下文件：ble.js、bleHandler.js、tools.js、error.js
实现下面步骤，就能够间接在小程序中应用蓝牙性能了。✨
示例
const emitter = new EventEmitter2();
const ble = new BLE(blename, emitter)
ble.listen(res => {if (res.type == 'connect') {switch(res.data){
case "未关上适配器"：break
case "蓝牙已连贯"：break
case ""
break
}
}else if (res.type == "response") {console.log('收到设施音讯响应：', res)
//TODO
}
})
ble.init()实现细节
应用办法如上，很简略，只须要保护一个全局的 ble 实例，则能够进行蓝牙的各种性能操作。第二部引入的那几个文件是用来干嘛的呢？
大体上将蓝牙的连贯、通信、保护过程按性能的复杂程度分为三层：BLE、BLEHandler、Tool，ble 更偏差用户层，blehandler 提供一些流程性管制，tool 则齐全是封装的微信 API，隔离一些简约的工作，使代码看起来简洁一些。
源码解析
import BLEHandler from "./bleHandler"
class BLE extends BLEHandler {constructor(blename, emitter) {super(blename, emitter)
}
listen(callback) {
// 蓝牙事件注册, 关上 channel
this.emitter.removeAllListeners("channel")
this.emitter.on("channel", callback)
}
removeListen() {
// 移除所有蓝牙事件
this.emitter.removeAllListeners("channel")
}
async init() {
let flow = false
// 关上蓝牙适配器状态监听
this.onBLEConnectionStateChange()
// 蓝牙适配器初始化
await this.openAdapter()
// 搜寻蓝牙设施
await this.startSearch()
// 获取设施 ID
flow = await this.onBluetoothFound()
// 进行搜寻设施
await this.stopSearchBluetooth()
if (!flow) return
// 连贯蓝牙
await this.connectBlue();
// 获取 serviceId
await this.getBLEServices()
// 设置特征值
await this.getCharacteristics();
// 订阅特征值
await this.notifyBLECharacteristicValueChange()
// 关上传输监听，期待设施反馈数据
this.onBLECharacteristicValueChange()}
// 发送指令
async send(mudata, cmd) {let flow = await this.sentOrder(mudata, cmd)
return flow
}
async close() {await this.closeBLEConnection()
await this.closeBLEAdapter()}
}
export {BLE};BLEHandler（promise 的封装，及 Eventenitter 通信管制）
import * as t from "./tools"
import {HTTP} from "../server";
/**
* 蓝牙工具类
* 封装小程序蓝牙流程办法
* 处理事件通信
*/
class BLEHandler {constructor(blename, emitter) {
this.blename = blename
this.emitter = emitter
this.readCharacteristicId = "";
this.writeCharacteristicId = "";
this.notifyCharacteristicId = "";
this.deviceId = "";
this.serviceId = "";
this.lastDate = new Date().getTime()
}
async openAdapter() {let [err, res] = await t._openAdapter.call(this);
if (err != null) {
this.emitter.emit("channel", {
type: "connect",
data: "未关上适配器"
})
return;
}
return true
}
async startSearch() {let [err, res] = await t._startSearch.call(this);
if (err != null) {return;}
this.emitter.emit("channel", {
type: "connect",
data: "蓝牙搜寻中"
})
}
async onBluetoothFound() {let [err, res] = await t._onBluetoothFound.call(this);
if (err != null) {
this.emitter.emit("channel", {
type: "connect",
data: "未找到设施"
})
// 勾销适配器
this.closeBLEAdapter()
wx.setStorageSync("bluestatus", "");
return;
}
this.emitter.emit("channel", {
type: "connect",
data: "正在连接中"
})
return true
}
async stopSearchBluetooth() {let [err, res] = await t._stopSearchBluetooth.call(this);
if (err != null) {return;}
}
async connectBlue() {let [err, res] = await t._connectBlue.call(this);
if (err != null) {return;}
}
async getBLEServices() {let [err, res] = await t._getBLEServices.call(this);
if (err != null) {return;}
}
async getCharacteristics() {let [err, res] = await t._getCharacteristics.call(this);
if (err != null) {
this.emitter.emit("channel", {
type: "connect",
data: "无奈订阅特征值"
})
// 勾销连贯
this.closeBLEConnection()
this.closeBLEAdapter()
wx.setStorageSync("bluestatus", "");
return;
}
return true
}
async notifyBLECharacteristicValueChange() {let [err, res] = await t._notifyBLECharacteristicValueChange.call(this);
if (err != null) {
// 勾销连贯
this.emitter.emit("channel", {
type: "connect",
data: "无奈订阅特征值"
})
this.closeBLEConnection()
this.closeBLEAdapter()
wx.setStorageSync("bluestatus", "");
return;
}
this.emitter.emit("channel", {
type: "connect",
data: "蓝牙已连贯"
})
wx.setStorageSync("bluestatus", "on");
return true
}
async closeBLEConnection() {let [err, res] = await t._closeBLEConnection.call(this);
if (err != null) {return;}
}
async closeBLEAdapter() {let [err, res] = await t._closeBLEAdapter.call(this);
if (err != null) {return;}
}
async sentOrder(mudata, cmd) {let data = t._sentOrder(mudata, cmd)
console.log("-- 发送数据:", data)
let arrayBuffer = new Uint8Array(data).buffer;
let [err, res] = await t._writeBLECharacteristicValue.call(this, arrayBuffer)
if (err != null) {return}
return true
}
// 关上蓝牙适配器状态监听
onBLEConnectionStateChange() {
wx.onBLEConnectionStateChange(res => {
// 该办法回调中能够用于解决连贯意外断开等异常情况
if (!res.connected) {this.closeBLEAdapter()
wx.setStorageSync("bluestatus", "");
this.emitter.emit("channel", {
type: "connect",
data: "蓝牙已断开"
})
}
}, err => {console.log('err', err)
})
}
// 收到设施推送的 notification
onBLECharacteristicValueChange() {
wx.onBLECharacteristicValueChange(res => {let arrbf = new Uint8Array(res.value)
console.log("收到上传数据：",arrbf)
console.log("工夫戳",new Date().getTime())
arrbf.map(res=>{console.log(res)
})
if (this._checkData(arrbf)) {if (arrbf[3] != 0x00) {let nowDate = new Date().getTime()
if ((nowDate - this.lastDate) > 900) {console.log('-- 节流 900ms,Lock!')
this.lastDate = nowDate
this._uploadInfo(arrbf)
this.emitter.emit("channel", {
type: "response",
data: arrbf
})
}
}
}
})
}
_uploadInfo(message) {console.log("-- 筹备数据同步！", this._mapToArray(message))
let bleorder = wx.getStorageSync("bleorder");
let blecabinet = wx.getStorageSync("blecabinet")
HTTP({
url: "cabinet/uploadBlueData",
methods: "post",
data: {
cabinetQrCode: blecabinet,
order: bleorder,
message: this._mapToArray(message)
}
}).then(res => {console.log("✔ 数据同步胜利！")
}, err => {console.log('✘ 数据同步失败', err)
})
}
_mapToArray(arrbf) {let arr = []
arrbf.map(item => {arr.push(item)
})
return arr
}
// 校验数据正确性
_checkData(arrbf) {
// 校验帧头帧尾
if (arrbf[0] != 0xEE || arrbf[1] != 0xFA || arrbf[arrbf.length - 1] != 0xFF || arrbf[arrbf.length - 2] != 0xFC) {console.log('✘ 帧头帧尾不匹配，请重发')
console.log('帧头:', arrbf[0])
console.log('帧头:', arrbf[1])
console.log('帧尾:', arrbf[arrbf.length - 1])
console.log('帧尾:', arrbf[arrbf.length - 2])
return false
}
// 校验 CRC
let crc = t._modBusCRC16(arrbf, 2, arrbf.length - 5)
if (arrbf[arrbf.length - 3] != crc & 0xff && arrbf[arrbf.length - 4] != (crc >> 8) & 0xff) {console.log('✘ crc 校验谬误，请重发')
return false
}
let time = new Date().toLocaleTimeString()
console.log(`✔ CRC 数据校验胜利！${arrbf[3] == 0 ? '❤' : '命令码：' + arrbf[3]}，time:${time}`)
return true
}
}
export default BLEHandler流程图
我的项目地址：https://github.com/arsize/ble
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