uniapp小程序连接蓝牙设备

一、初始化蓝牙模块

这一步是必须的，在开发项目过程中，初始化蓝牙模块之后，紧接着就要开启一些监听的api，供后续设备读写数据时监听变化。

initBLE(callback) {//提前定义变量，直接在uni的api中使用this是不可以的var self = this;// `第一步：初始化蓝牙模块`uni.openBluetoothAdapter({success: function (e) {utils.toast("初始化蓝牙适配器成功");},fail: function (e) {utils.toast("初始化蓝牙适配器失败 : " + JSON.stringify(e));},});// `检查蓝牙适配器状态变化`// `这一步主要是为了在连接成功蓝牙之后关闭蓝牙搜索，蓝牙搜索非常耗费性能`uni.onBluetoothAdapterStateChange(function (e) {self.bluetooth.available = e.available;if (!e.available) {utils.toast("蓝牙适配器不可用");if (self.bluetooth.startDiscovery) {self.bluetooth.startDiscovery = false;self.stopBluetoothDevicesDiscovery();}}});// `监听搜索到设备`uni.onBluetoothDeviceFound(function (e) {// `当搜索到设备后，可以在e.devices中获取到设备信息列表`if (!e.devices) return;for (var i = 0; i < e.devices.length; i++) {var device = e.devices[i];for (var j = 0; j < self.discoveryList.length; j++) {var item = self.discoveryList[j];// 去重if (item.deviceId === device.deviceId) {return;}}self.discoveryList.push(device);}});// `监听蓝牙设备连接变化`uni.onBLEConnectionStateChange(function (e) {// 该方法回调中可以用于处理连接意外断开等异常情况self.currentDeviceStatus = e.connected ? 1 : 2;// 在连续盘点过程中是不允许断开的，万一因为其他什么原因断开了，则尝试停止连续盘点if (!e.connected && self.inventoryLabelForm.looping) {self.sendStopLoopInventoryCmd(); //停止盘点}});// `读数据`uni.onBLECharacteristicValueChange(function (e) {if (e.deviceId != self.currentDevice.deviceId) return;var value = self.buffer2Hex(e.value);console.log(e); //查看是否有R20固定返回值utils.toast("读数据178：" + JSON.stringify(e));self.lastRcvData += value;self.doRcvData();});self.historyList = utils.getHistoryList();// 如果有cb回调函数，则需要停止下拉刷新if (callback) {// setTimeout这里等待一下上面的异步初始化setTimeout(() => {callback();}, 1000);}},

二、开始搜索

以上只是蓝牙的初始化操作，要想真正实现蓝牙连接从第二步开始

// 开启蓝牙搜索服务startBluetoothDevicesDiscovery() {var self = this;// 小程序环境需要等待一下，不然会报错setTimeout(() => {// 开始搜寻附近的蓝牙外围设备uni.startBluetoothDevicesDiscovery({allowDuplicatesKey: false,success: function (e) {self.bluetooth.discoverying = true;//开启搜索成功，此时初始化中定义的onBluetoothDeviceFound会自动执行},fail: function (e) {utils.toast("开始搜索蓝牙设备失败 : " + JSON.stringify(e));},});}, 1000);},

三、连接蓝牙

目前为止我们已经搜索到蓝牙设备了，下面要做的就是在蓝牙列表中选择对应的蓝牙设备进行连接

// 连接设备onConnectDevice(device) {// `device是选择的设备对象，在这可以取到设备的deviceId供后续使用`var self = this;this.onCloseDiscoveryDialog();this.onCloseHistoryDialog();this.currentDevice = device;this.currentDeviceStatus = 3;this.lastRcvData = "";// 创建一个BLE连接uni.createBLEConnection({deviceId: device.deviceId,//这里使用设备id来创建连接success: function (e) {// 创建完成后获取服务（这在ios中是必须的，否则会导致后面读取数据失败）uni.getBLEDeviceServices({// 这里的 deviceId 需要已经通过 createBLEConnection 与对应设备建立链接deviceId: device.deviceId,success(res) {// 获取特征值（这在ios中是必须的，否则会导致后面读取数据失败）uni.getBLEDeviceCharacteristics({// 这里的 deviceId 需要已经通过 createBLEConnection 与对应设备建立链接deviceId: device.deviceId,// 这里的 serviceId 需要在 getBLEDeviceServices 接口中获取serviceId: RX_SERVICE_UUID, //因为这里使用的是固定服务所以事先定义过常量了，这里直接使用success(res) {// 创建连接-获取服务-获取特征值之后就可以开启nofity功能了self.enableBleNotify(device);},fail() {},});},});// 开启nofity功能self.enableBleNotify(device);},fail: function (e) {utils.toast("连接蓝牙设备失败 : " + JSON.stringify(e));self.currentDeviceStatus = 2;},});// 保存设备到历史记录里var flag = true;for (var i = 0; i < this.historyList.length; i++) {var item = this.historyList[i];if (item.deviceId === device.deviceId) {this.historyList[i] = device;flag = false;}}if (flag) {this.historyList.push(device);}utils.saveHistoryList(this.historyList);},

四、监听特征值变化

 enableBleNotify(device) {// 这里监听时,ios测试需要有点延迟,安卓的话,只在测试机上测试过,不需要延迟// 这里延迟1秒兼容,反正差距不大setTimeout(function () {uni.notifyBLECharacteristicValueChange({state: true,deviceId: device.deviceId,serviceId: RX_SERVICE_UUID,characteristicId: R_UUID,success: function (e) {//到了此时蓝牙才算真正的连接成功},fail: function (e) {},});}, 1000);},

五、调用示例

这里以单次盘点为例

 // 单步盘点标签async  onOneStepInventory() {var self = this;if (!this.checkDeviceConnect()) return;this.inventoryLabelForm.startTime = utils.currentTimeMillis(); //获取盘点时间的// 单步盘点关闭enableRssithis.inventoryLabelForm.enableRssi = false;// 发送固定值await this.sendR20Hex(); //这里是定制需要没有可以省去var cmd = this.generateUHFProtocl(0x80, utils.number2Hex(5000, 2));self.sendData(cmd);},//发送固定值async sendR20Hex() {await this.sendData("A55A0029F011D75238EE46C3ECFFCE3B9AFC093ACC13F711A6ADF3FF76ACE59A8DF1BA704E22EC0D0A");},//写入操作（发送数据，连续存盘指令自行实现了，不调用该方法）async sendData(hexStr, serviceId, characteristicId) {if (utils.isBlank(hexStr)) return;serviceId = serviceId || RX_SERVICE_UUID;characteristicId = characteristicId || W_UUID;var self = this;var sendData;// ble发送数据时，需要分包，最多20字节if (hexStr.length > 40) {sendData = hexStr.substr(0, 40);hexStr = hexStr.substr(40, hexStr.length - 40);} else {sendData = hexStr;hexStr = null;}this.logSend(sendData);var buffer = new ArrayBuffer(sendData.length / 2);var bufView = new Uint8Array(buffer);for (var i = 0; i < sendData.length; i += 2) {bufView[i / 2] = parseInt(sendData.substr(i, 2), 16);}//这里写了一个promise是为了在执行正常操作之前，先执行固定值操作return new Promise((resolve, reject) => {uni.writeBLECharacteristicValue({deviceId: self.currentDevice.deviceId,serviceId: serviceId,characteristicId: characteristicId,value: buffer,success: async function (e) {if (hexStr) {//超过20字节 递归循环写入await self.sendData(hexStr);}console.log("写入数据成功391" + sendData);// 由于写字节限制，如果还有未发送完的数据，接着继续发送resolve();},fail: function (e) {},});});},

utils.js文件

这里主要存放一些转换方法，上面用到的utils.xx方法可以在此处查看

export default {alert: function (content, title = "提示") {uni.showModal({title,content,showCancel: false,success: function (res) {},});},confirm: function (content, title = "提示") {uni.showModal({title,content,success: function (res) {if (res.confirm) {console.log("用户点击确定");} else if (res.cancel) {console.log("用户点击取消");}},});},toast: function (title, duration = 1000) {uni.showToast({title,icon: "none",duration,});},showWaiting: function (title = "加载中") {uni.showLoading({title,});},closeWaiting: function () {uni.hideLoading();},actionSheet: function (itemList) {uni.showActionSheet({itemList,success: function (res) {console.log("选中了第" + (res.tapIndex + 1) + "个按钮");},fail: function (res) {console.log(res.errMsg);},});},saveHistoryList: function (list) {try {uni.setStorageSync("history_list", JSON.stringify(list));} catch (e) {// error}},getHistoryList: function () {try {const value = uni.getStorageSync("history_list");if (value) {return JSON.parse(value);} else {return [];}} catch (e) {// error}},clearHistoryList: function () {try {uni.removeStorageSync("history_list");} catch (e) {// error}},leftPad: function (value, length, fill) {while (length - value.length > 0) {value = fill + value;}return value;},number2Hex: function (value, byteLength) {value = parseInt(value);var hex = value.toString(16).toUpperCase();byteLength = byteLength || hex.length / 2 + (hex.length % 2);return this.leftPad(hex, byteLength * 2, "0");},bin2Hex: function (value, byteLength) {byteLength = byteLength || 1;byteLength = Math.max(value.length / 8 + (value.length % 8 > 0 ? 1 : 0),byteLength);value = this.leftPad(value, byteLength * 8, "0");var hex = "";for (var i = 0; i < value.length; i += 8) {hex += this.number2Hex(parseInt(value.substr(i, 8), 2), 1);}return hex;},isNull: function (value) {if (value == null) return true;if ("undefined" == typeof value) return true;return false;},isString: function (value) {return "[object String]" === Object.prototype.toString.call(value);},isBlank: function (value) {if (this.isNull(value)) return true;if (!this.isString(value)) return true;if (value.trim().length == 0) return true;return false;},str2Hex: function (str) {var hex = "";for (var i = 0; i < str.length; i++) {hex += this.number2Hex(str.charCodeAt(i), 1);}return hex;},currentTimeMillis: function () {return new Date().getTime();},hex2ByteArray: function (hex) {var result = [];for (var i = 0; i < hex.length; i += 2) {var value = parseInt(hex.substr(i, 2), 16);if (value > 127) {value -= 0x100;}result.push(value);}return result;},/*** hex转字符串* @param {Object} hex* @param {Object} charset	编码格式，默认为utf-8*/hex2Str: function (hex, charset = "utf-8") {var bytesArray = this.hex2ByteArray(hex);try {var str;// 创建一个TextDecoder对象，指定所需的编码格式const decoder = new TextDecoder(charset);// 将ByteArray转换为字符串str = decoder.decode(bytesArray);return str;} catch (e) {this.toast("错误的编码格式");}},
};