uni-app 蓝牙传输

信步琴弦 發表於 2022-7-6 13:14:00

最近在做一个项目，要求app通过蓝牙连接设备并将报文传输至设备中，在这个过程踩过了几个坑，总结如下：
根据uni-app官网API主要涉及到“蓝牙”和“低功耗蓝牙”两个部分。
主要步骤：
<h2>步骤1：初始化蓝牙模块 openBluetoothAdapter</h2>
<div class="cnblogs_code">
<pre>$openBluetoothAdapter(){
 uni.openBluetoothAdapter({
 success: (res) => {
 //初始化成功，搜索设备
 console.log('openBluetoothAdapter success', res);
 uni.showLoading({
 title: '搜索设备中'
 });
 setTimeout(()=>{
 this.baseList=[];//每次扫码清空设备列表，不然会导致重复
 this.$startBluetoothDevicesDiscovery();//扫码蓝牙设备
 },100);

 //定时关闭搜索设备
 setTimeout(()=>{
 this.$stopBluetoothDevicesDiscovery();
 uni.hideLoading();
 },10*1000);

 },
 fail: (res) => {
 uni.showToast({
 title: '请打开蓝牙',
 duration: 1000
 });
 if (res.errCode === 10001) {
 //监听蓝牙适配器状态变化事件
 uni.onBluetoothAdapterStateChange(function(res){
 console.log('onBluetoothAdapterStateChange', res);
 if (res.available) {
 //开始扫描
 this.$startBluetoothDevicesDiscovery()
 }
 })
 }
 }
 })
 },</pre>
</div>
<h2>步骤2：搜索附近的蓝牙外围设备 startBluetoothDevicesDiscovery</h2>
<div class="cnblogs_code">
<pre>//2.搜索附近的蓝牙外围设备
 $startBluetoothDevicesDiscovery(){
 if (this._discoveryStarted) {
 return;
 }
 this._discoveryStarted = true;
 //开始搜寻附近的蓝牙外围设备
 uni.startBluetoothDevicesDiscovery({
 allowDuplicatesKey: true,
 success: (res) => {
 console.log('startBluetoothDevicesDiscovery success', res);
 //监听寻找到新设备的事件
 this.$onBluetoothDeviceFound()
 },
 fail:err=>{
 console.error("startBluetoothDevicesDiscoveryErr",err);
 uni.showToast({
 icon:'none',
 duration:2000,
 title:"请检查蓝牙状态",
 });
 }
 })
 },</pre>
</div>
<h2>步骤3：监听寻找到新设备 onBluetoothDeviceFound</h2>
<div class="cnblogs_code">
<pre>$onBluetoothDeviceFound(){
 let that =this;
 //监听寻找到新设备的事件
 uni.onBluetoothDeviceFound(function(res){
 res.devices.forEach(device => {

 if (!device.name && !device.localName) {
 return;
 }
 //添加蓝牙设备列表
 let oneBluetooth={
 deviceId: device.deviceId,
 name: device.name,
 RSSI:device.RSSI,
 localName:device.localName
 }
 //判断是否存在
 if(that.bluetoothIndex.indexOf(device.deviceId) ==-1){
 that.baseList.push(oneBluetooth);
 that.bluetoothIndex.push(device.deviceId);
 }
 //如果名字相同连接设备
 //if(device.name == devicename){
 //$createBLEConnection(device.deviceId);
 //}
 })
 })
 },</pre>
</div>
<h2>步骤4：创建连接蓝牙事件  createBLEConnection</h2>
<div class="cnblogs_code">
<pre>$createBLEConnection(deviceId){
 let that=this;

 //1）判断设备是否处于连接状态
 if(that.Connecting){
 uni.showToast({
 icon:'none',
 duration:2000,
 title:"设备已连接",
 });
 return
 }
 //2）创建连接
 uni.showLoading({
 title: '设备连接中',
 mask:true,
 });
 uni.createBLEConnection({
 deviceId:deviceId,
 success: (res) => {
 that._deviceId = deviceId;
 //不延迟造成获取不到服务！！！！，我走过的坑！！！
 setTimeout(function() {
 //获取设备的蓝牙服务
 that.$getBLEDeviceServices(deviceId);
 //关闭等待提示
 setTimeout(function () {uni.hideLoading();}, 100);
 }, 7000);
 },
 fail: (err) =>{
 console.log(err);
 }
 });

 //3）设置MTU，否则传输报文不全，默认是23bytes，但是蓝牙本身是需要3bytes，故而只能传输20bytes
 setTimeout(()=>{
 console.log('deviceId>>>',deviceId);
 uni.setBLEMTU({
 deviceId:deviceId,
 mtu:255,
 success:(res)=>{
 console.log('设置MTU最大值成功',res);
 },
 fail:(res)=>{
 console.log('设置MTU最大值失败',res);
 }
 });
 },9000);


 //4）关闭搜索
 this.$stopBluetoothDevicesDiscovery();
 },</pre>
</div>
<h2>步骤5：获取蓝牙设备的所有服务 getBLEDeviceServices</h2>
<div class="cnblogs_code">
<pre>$getBLEDeviceServices(deviceId){
 //获取蓝牙设备所有服务(service)
 uni.getBLEDeviceServices({
 deviceId,
 success: (res) => {
 console.log('250res.services>>>',res.services);

 for (let i = 0; i < res.services.length; i++) {
 if (res.services.isPrimary) {
 this.$getBLEDeviceCharacteristics(deviceId, res.services.uuid);
 return;
 }
 }
 }
 });
 },</pre>
</div>
<h2>步骤6：获取蓝牙设备某个服务中所有特征值（characteristic）getBLEDeviceCharacteristics</h2>
<div class="cnblogs_code">
<pre>$getBLEDeviceCharacteristics(deviceId,serviceId){
 let that = this;
 //获取蓝牙设备某个服务中所有特征值(characteristic)。
 uni.getBLEDeviceCharacteristics({
 deviceId,
 serviceId,
 success: (res) => {
 console.log('288getBLEDeviceCharacteristics success', res.characteristics);
 for (let i = 0; i < res.characteristics.length; i++) {
 let item = res.characteristics
 //if (item.properties.read) {
 //读取低功耗蓝牙设备的特征值的二进制数据值。1
 uni.readBLECharacteristicValue({
 deviceId,
 serviceId,
 characteristicId: item.uuid,
 })
 //}
 if (item.properties.write) {
 this._deviceId = deviceId;
 this._serviceId = serviceId;
 this._characteristicId = item.uuid;
 //写入请求数据
 this.$writeBLECharacteristicValue();
 }
 //if (item.properties.notify || item.properties.indicate) {
 //启用低功耗蓝牙设备特征值变化时的 notify 功能，订阅特征值。
 uni.notifyBLECharacteristicValueChange({
 deviceId,
 serviceId,
 characteristicId: item.uuid,
 state: true,
 success(res)
 {
 // console.log('notifyBLECharacteristicValueChange success:' + res.errMsg);
 // console.log(JSON.stringify(res));
 uni.onBLECharacteristicValueChange(characteristic => {
 console.log('监听低功耗蓝牙设备的特征值变化事件成功>>');
 //将字节转换成16进制字符串
 var data = ab2hex(characteristic.value)
 //将16进制转成字符串
 let newdataStr = Buffer.from(data,'hex');//先把数据存在buf里面
 //that.btvalue=newdataStr.toString("utf-8");//使用toString函数就能转换成字符串
 //设备返回SN
 that.SN=newdataStr.toString("utf-8");
 console.log('设备返回SN>>>',that.SN);
 //根据返回的数据处理设备类型和显示的输入区域-----------------
 that.getEquType(that.SN);
 });
 }

 });
 //}
 }
 },
 fail(res) {
 console.error('getBLEDeviceCharacteristics', res)
 }
 })
 },</pre>
</div>
<h2>步骤7：向蓝牙设备发送一个16进制数据</h2>
<div class="cnblogs_code">
<pre> $writeBLECharacteristicValue(){
 let buffer = new ArrayBuffer(1)
 let dataView = new DataView(buffer);
 dataView.setUint8(0, 0);//0x61 | 0
 uni.writeBLECharacteristicValue({
 deviceId: this._deviceId,
 serviceId: this._serviceId,//"0000FE61-0000-1000-8000-00805F9B34FB",
 characteristicId: this._characteristicId,
 value: buffer,
 success: function(res){
 console.log('350',res);
 },
 fail: function(res){
 console.log(res);
 }
 })
 },</pre>
</div>
<h2>步骤8：向蓝牙设备发送字符串数据 writeBLECharacteristicValueString</h2>
<div class="cnblogs_code">
<pre>$writeBLECharacteristicValueString(str){
 // 发送方式一
 let buffer = new ArrayBuffer(str.length);
 let dataView = new DataView(buffer);
 for (let i in str) {
 dataView.setUint8(i, str.charCodeAt() | 0);
 //打印二进制字节
 //console.log('dataView.getUint8(i)>>',dataView.getUint8(i));
 }
 //延迟发送指令
 setTimeout(()=>{

 uni.writeBLECharacteristicValue({
 deviceId: this._deviceId,
 serviceId: this._serviceId,
 characteristicId: this._characteristicId,//"0000FE61-0000-1000-8000-00805F9B34FB",//,
 value: buffer,
 success: function(res){
 console.log("命令写入成功",res);
 },
 fail: function(res){
 console.error("命令写入失败",res);
 }
 });
 },2000);
 },</pre>
</div>
<h2>步骤9：关闭搜索  stopBluetoothDevicesDiscovery</h2>
<div class="cnblogs_code">
<pre> $stopBluetoothDevicesDiscovery(){
 //关闭搜索
 uni.stopBluetoothDevicesDiscovery({
 success(res) {
 this._discoveryStarted=false;
 }
 })
 },</pre>
</div>
<h2>步骤10：断开蓝牙设备连接 closeBLEConnect</h2>
<div class="cnblogs_code">
<pre>$closeBLEConnect(deviceId){
 uni.closeBLEConnection({
 deviceId,
 success:res=>{
 this.deviceId = "";
 console.log("断开成功",res);
 },
 fail:err=>{
 console.error("断开错误",err);
 }
 })
 },</pre>
</div>
需要注意的是：
1）和蓝牙设备通讯不能太频繁。
2）写入数据时候要注意特性值UUID。
3）写入数据超过20bytes时候需要设置MTU。否则传输的内容将被截取，造成传输信息不完整。
本文参考：https://blog.csdn.net/qq_33259323/article/details/105609275
                 https://www.jianshu.com/p/c627ddc7862d
　　　　　https://uniapp.dcloud.io/api/system/bluetooth.html
      　　　https://uniapp.dcloud.io/api/system/ble.html 
来源：https://www.cnblogs.com/ckfuture/p/16450418.html

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uni-app 蓝牙传输