#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()
```js
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
```js
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：
```js
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*/
```js
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
```js
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
```js
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，
```js
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
```js
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
```js
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
```js
// 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
