微信小程序连接蓝牙设备

最近再弄小程序连接蓝牙，分享一下。

首先值得注意的是，微信小程序只支持连接低功耗蓝牙设备

部分oppo和vivo手机要把定位也打开，否则搜索不到附近蓝牙设备（比如我坑爹的oppoR11就必须把定位和蓝牙都打开才行）

下面直接上代码，复制粘贴就行，然后点击“开始扫描”（目前我知道苹果手表是低功耗设备，大家可以连接试一下）

然后点击要连的设备：

wxml：

<wxs module="utils">
module.exports.max = function(n1, n2) {
  return Math.max(n1, n2)
}
module.exports.len = function(arr) {
  arr = arr || []
  return arr.length
}
</wxs>
<button bindtap="openBluetoothAdapter">开始扫描</button>
<button bindtap="stopBluetoothDevicesDiscovery">停止扫描</button>
<button bindtap="getBluetoothAdapterState">结束流程</button>

<view class="devices_summary">已发现 {{devices.length}} 个外围设备：</view>
<scroll-view class="device_list" scroll-y scroll-with-animation>
  <view wx:for="{{devices}}" wx:key="index"
   data-device-id="{{item.deviceId}}"
   data-name="{{item.name || item.localName}}"
   bindtap="createBLEConnection" 
   class="device_item"
   hover-class="device_item_hover">
    <view style="font-size: 16px; color: #333;">{{item.name}}</view>
    <view style="font-size: 10px">信号强度: {{item.RSSI}}dBm ({{utils.max(0, item.RSSI + 100)}}%)</view>
    <view style="font-size: 10px">UUID: {{item.deviceId}}</view>
    <view style="font-size: 10px">Service数量: {{utils.len(item.advertisServiceUUIDs)}}</view>
  </view>
</scroll-view>

<view class="connected_info" wx:if="{{connected}}">
  <view>
    <text>已连接到 {{name}}</text>
    <view class="operation">
    <button wx:if="{{canWrite}}" size="mini" bindtap="writeBLECharacteristicValue">写数据</button>
    <button size="mini" bindtap="closeBLEConnection">断开连接</button>
    </view>
  </view>
  <view wx:for="{{chs}}" wx:key="index" style="font-size: 12px; margin-top: 10px;">
    <view>特性UUID: {{item.uuid}}</view>
    <view>特性值: {{item.value}}</view>
  </view>
</view>

wxss:

page {
  color: #333;
}
.devices_summary {
  margin-top: 30px;
  padding: 10px;
  font-size: 16px;
}
.device_list {
  height: 300px;
  margin: 50px 5px;
  margin-top: 0;
  border: 1px solid #EEE;
  border-radius: 5px;
  width: auto;
}
.device_item {
  border-bottom: 1px solid #EEE;
  padding: 10px;
  color: #666;
}
.device_item_hover {
  background-color: rgba(0, 0, 0, .1);
}
.connected_info {
  position: fixed;
  bottom: 0;
  width: 100%;
  background-color: #F0F0F0;
  padding: 10px;
  padding-bottom: 20px;
  margin-bottom: env(safe-area-inset-bottom);
  font-size: 14px;
  min-height: 100px;
  box-shadow: 0px 0px 3px 0px;
}
.connected_info .operation {
  position: absolute;
  display: inline-block;
  right: 30px;
}

js：

const app = getApp()

function inArray(arr, key, val) {
  for (let i = 0; i < arr.length; i++) {
    if (arr[i][key] === val) {
      return i;
    }
  }
  return -1;
}

// ArrayBuffer转16进度字符串示例
function ab2hex(buffer) {
  var hexArr = Array.prototype.map.call(
    new Uint8Array(buffer),
    function (bit) {
      return ('00' + bit.toString(16)).slice(-2)
    }
  )
  return hexArr.join('');
}

Page({
  data: {
    devices: [],
    connected: false,
    chs: [],
  },
  openBluetoothAdapter() {
    wx.openBluetoothAdapter({
      success: (res) => {
        console.log('openBluetoothAdapter success', res)
        this.startBluetoothDevicesDiscovery()
      },
      fail: (res) => {
        console.log('error', res)
        if (res.errCode === 10001) {
          wx.onBluetoothAdapterStateChange(function (res) {
            console.log('onBluetoothAdapterStateChange', res)
            if (res.available) {
              this.startBluetoothDevicesDiscovery()
            }
          })
        }
      }
    })
  },
  getBluetoothAdapterState() {
    wx.getBluetoothAdapterState({
      success: (res) => {
        console.log('getBluetoothAdapterState', res)
        if (res.discovering) {
          this.onBluetoothDeviceFound()
        } else if (res.available) {
          this.startBluetoothDevicesDiscovery()
        }
      }
    })
  },
  startBluetoothDevicesDiscovery() {
    if (this._discoveryStarted) {
      return
    }
    this._discoveryStarted = true
    wx.startBluetoothDevicesDiscovery({
      allowDuplicatesKey: true,
      success: (res) => {
        console.log('lanya', res)
        this.onBluetoothDeviceFound()
      },
    })
  },
  stopBluetoothDevicesDiscovery() {
    wx.stopBluetoothDevicesDiscovery()
  },
  onBluetoothDeviceFound() {
    wx.onBluetoothDeviceFound((res) => {
      res.devices.forEach(device => {
        if (!device.name && !device.localName) {
          return
        }
        const foundDevices = this.data.devices
        const idx = inArray(foundDevices, 'deviceId', device.deviceId)
        const data = {}
        if (idx === -1) {
          data[`devices[${foundDevices.length}]`] = device
        } else {
          data[`devices[${idx}]`] = device
        }
        this.setData(data)
      })
    })
  },
  createBLEConnection(e) {
    const ds = e.currentTarget.dataset
    const deviceId = ds.deviceId
    const name = ds.name
    wx.createBLEConnection({
      deviceId,
      success: (res) => {
        this.setData({
          connected: true,
          name,
          deviceId,
        })
        this.getBLEDeviceServices(deviceId)
      }
    })
    this.stopBluetoothDevicesDiscovery()
  },
  closeBLEConnection() {
    wx.closeBLEConnection({
      deviceId: this.data.deviceId
    })
    this.setData({
      connected: false,
      chs: [],
      canWrite: false,
    })
  },
  getBLEDeviceServices(deviceId) {
    wx.getBLEDeviceServices({
      deviceId,
      success: (res) => {
        for (let i = 0; i < res.services.length; i++) {
          if (res.services[i].isPrimary) {
            this.getBLEDeviceCharacteristics(deviceId, res.services[i].uuid)
            return
          }
        }
      }
    })
  },
  getBLEDeviceCharacteristics(deviceId, serviceId) {
    wx.getBLEDeviceCharacteristics({
      deviceId,
      serviceId,
      success: (res) => {
        console.log('getBLEDeviceCharacteristics success', res.characteristics)
        for (let i = 0; i < res.characteristics.length; i++) {
          let item = res.characteristics[i]
          if (item.properties.read) {
            wx.readBLECharacteristicValue({
              deviceId,
              serviceId,
              characteristicId: item.uuid,
            })
          }
          if (item.properties.write) {
            this.setData({
              canWrite: true
            })
            this._deviceId = deviceId
            this._serviceId = serviceId
            this._characteristicId = item.uuid
            this.writeBLECharacteristicValue()
          }
          if (item.properties.notify || item.properties.indicate) {
            wx.notifyBLECharacteristicValueChange({
              deviceId,
              serviceId,
              characteristicId: item.uuid,
              state: true,
            })
          }
        }
      },
      fail(res) {
        console.error('getBLEDeviceCharacteristics', res)
      }
    })
    // 操作之前先监听，保证第一时间获取数据
    wx.onBLECharacteristicValueChange((characteristic) => {
      const idx = inArray(this.data.chs, 'uuid', characteristic.characteristicId)
      const data = {}
      if (idx === -1) {
        data[`chs[${this.data.chs.length}]`] = {
          uuid: characteristic.characteristicId,
          value: ab2hex(characteristic.value)
        }
      } else {
        data[`chs[${idx}]`] = {
          uuid: characteristic.characteristicId,
          value: ab2hex(characteristic.value)
        }
      }
      // data[`chs[${this.data.chs.length}]`] = {
      //   uuid: characteristic.characteristicId,
      //   value: ab2hex(characteristic.value)
      // }
      this.setData(data)
    })
  },
  writeBLECharacteristicValue() {
    // 向蓝牙设备发送一个0x00的16进制数据
    let buffer = new ArrayBuffer(1)
    let dataView = new DataView(buffer)
    dataView.setUint8(0, Math.random() * 255 | 0)
    wx.writeBLECharacteristicValue({
      deviceId: this._deviceId,
      serviceId: this._deviceId,
      characteristicId: this._characteristicId,
      value: buffer,
    })
  },
  closeBluetoothAdapter() {
    wx.closeBluetoothAdapter()
    this._discoveryStarted = false
  },
})