微信小程序之蓝牙打印
蓝牙打印
蓝牙打印热敏纸是我工作第一个小程序项目时用到的，当时啃下这块硬骨头是真的感觉好难，这篇文章我将监听蓝牙特征这部分删减掉了，减少难度，而且我个人使用中感觉也不是那么必须。
微信开发者文档-蓝牙
app.js
// 全局变量，蓝牙对象模板,但是在初始化蓝牙之前需要删除数据。
globalData: {
btDevices: [
{
id: 1,
rssi: -40, // 信号
name: 'BT626', // 蓝牙设备名称
devId: '0', // 蓝牙序列id
img: '/imgs/scan/2.png', // 蓝牙图标
},
],
}
首先：判断是Android还是iOS
if(app.globalData.platform == 'ios'){
console.log('ios bt')
}else{
console.log('android bt')
}
第一阶段
第一步：初始化蓝牙设备
wx.openBluetoothAdapter({
success: function (res) {
},
fail:function(res){
console.log("蓝牙未开启！");
}
})
第二步：搜索附近蓝牙设备
wx.startBluetoothDevicesDiscovery({
success: function (res) {
})
第三步：监听寻找到新设备的事件
wx.onBluetoothDeviceFound(function(devices) {
})
第四步：获取已搜素到的蓝牙设备列表
wx.getBluetoothDevices({
success: function (res) {
var ln = 0;
console.log(res,that.data.btDevices.length)
if(that.data.btDevices.length != null)
ln = that.data.btDevices.length
for (var i = ln; i < res.devices.length; ++i) {
var rssi_level_img;
if(res.devices[i].RSSI > 0 || res.devices[i].name == '未知设备'){
continue;
}
if(res.devices[i].RSSI > -40) {
rssi_level_img = '/imgs/scan/5.png'
} else if(res.devices[i].RSSI > -50){
rssi_level_img = '/imgs/scan/4.png'
} else if(res.devices[i].RSSI > -60){
rssi_level_img = '/imgs/scan/3.png'
} else if(res.devices[i].RSSI > -70){
rssi_level_img = '/imgs/scan/2.png'
}else{
rssi_level_img = '/imgs/scan/1.png'
}
var newBtDevice = [{
rssi : res.devices[i].RSSI,
name : res.devices[i].name,
devId : res.devices[i].deviceId,
img : rssi_level_img,
}];
for (var k = 0; k < that.data.btDevices.length; ++k){
if(res.devices[i].deviceId == that.data.btDevices[k].devId){
that.data.btDevices.splice(k,1);
break;
}
}
that.data.btDevices = that.data.btDevices.concat(newBtDevice)
}
that.setData({
btDevices : that.data.btDevices
});
app.globalData.btDevices = that.data.btDevices
}
})
下拉刷新
// 下拉清空记录，并重新搜索
onPullDownRefresh: function() {
var that = this
//停止当前页面下拉刷新
wx.stopPullDownRefresh()
wx.stopBluetoothDevicesDiscovery({
success: function (res) {
//关闭蓝牙模块
wx.closeBluetoothAdapter({
success: function (res) {
console.log("关闭蓝牙模块")
var num = that.data.btDevices.length
that.data.btDevices.splice(0,num)
that.setData({
btDevices : that.data.btDevices
});
//蓝牙模块初始化
wx.openBluetoothAdapter({
success: function (res) {
console.log("蓝牙模块初始化")
wx.startBluetoothDevicesDiscovery({
//services: ['FFF0'],
success: function (res) {
console.log("搜索附近蓝牙设备")
}
})
},
fail:function(res){
console.log("蓝牙未开启！下拉！");
}
})
}
})
}
})
},
第二阶段
这是蓝牙打印最终重要的三个数据。
// 蓝牙设备id
devId: openid.devId,
// 蓝牙打印设备服务id
writeServiceId: '',
//蓝牙打印设备特征值id
writeCharacteristicId: '',
// 蓝牙打印设备服务序列
writeServiceSearchIndex: 0,
第五步：连接蓝牙设备
wx.createBLEConnection({
// 这里的 deviceId需要在上面的 getBluetoothDevices 或 onBluetoothDeviceFound 接口中获取,这个devId是你点击选择连接的蓝牙
deviceId: app.globalData.btDevices[i].devId,
});
第六步： 获取蓝牙服务
wx.getBLEDeviceServices({
deviceId: app.globalData.btDevices[i].devId,
})
第七步： 获取蓝牙设备某个服务中所有特征值
wx.getBLEDeviceCharacteristics({
// 这里的 devId 需要在 getBluetoothDevices 或 onBluetoothDeviceFound 接口中获取
deviceId: app.globalData.btDevices[i].devId,
// 这里的 writeServiceId 需要在 getBLEDeviceServices 接口中获取
serviceId: that.data.services[that.data.writeServiceSearchIndex].uuid
complete: function () {
//递归调用自身直到找到write特征或遍历完所有特征
that.seekFirstWriteCharacteristic()
},
success: function (res) {
console.log('device getBLEDeviceCharacteristics:', res.characteristics)
for (var n = 0; n < res.characteristics.length && that.data.writeCharacteristicId == 'invalid'; ++n) {
if (res.characteristics[n].properties.write == true) {
that.data.writeCharacteristicId = res.characteristics[n].uuid
}
}
}
})
第八步：打印
需要一个cpcl文件，要将服务器的值传到 utils/cpcl.js里去。通过字符串操作赋值。
//将字符串转成arrayBuffer
base64Str = gbToBase64.encode64(sendData)
arrayBuffer = wx.base64ToArrayBuffer(base64Str);
if (app.globalData.platform == 'ios') {
wx.writeBLECharacteristicValue({
// 这里的 devId 需要在 getBluetoothDevices 或 onBluetoothDeviceFound 接口中获取
deviceId: that.data.devId,
// 这里的 serviceId 需要在 getBLEDeviceServices 接口中获取
serviceId: that.data.writeServiceId,
// 这里的 writeCharacteristicId 需要在上面的 getBLEDeviceCharacteristics 接口中获取
characteristicId: that.data.writeCharacteristicId,
// 这里的value是ArrayBuffer类型
value: arrayBuffer,
success: function (res) {
wx.showToast({
title: '发送成功',
icon: 'success',
duration: 2000
})
that.setData({
block:"block",
block1: "none"
})
console.log('writeBLECharacteristicValue success', res.errMsg)
},
fail: function (res) {
console.log('writeBLECharacteristicValue fail', res.errMsg)
}
})
} else {
let dataView1 = new DataView(arrayBuffer)
var length = dataView1.byteLength
var size = 100
var package_count = Math.round(length / size + 0.5);
this.writeFuction(that, arrayBuffer, package_count, size);
}
writeFuction(that, data, count, size) {
let dataView_temp1 = new DataView(data);
var packages = Math.round(dataView_temp1.byteLength / size + 0.5)
var yushu = dataView_temp1.byteLength % size
let buffer = null
let dataView_temp2 = null
if (yushu != 0 && count == 1) {
buffer = new ArrayBuffer(yushu)
dataView_temp2 = new DataView(buffer)
for (var i = 0; i < dataView_temp2.byteLength; i++) {
dataView_temp2.setUint8(i, dataView_temp1.getUint8((packages - count) * size + i))
}
} else {
buffer = new ArrayBuffer(size)
dataView_temp2 = new DataView(buffer)
for (var i = 0; i < dataView_temp2.byteLength; i++) {
dataView_temp2.setUint8(i, dataView_temp1.getUint8((packages - count) * size + i))
}
}
wx.writeBLECharacteristicValue({
// 这里的 devId 需要在 getBluetoothDevices 或 onBluetoothDeviceFound 接口中获取
deviceId: that.data.devId,
// 这里的 serviceId 需要在 getBLEDeviceServices 接口中获取
serviceId: that.data.writeServiceId,
// 这里的 writeCharacteristicId 需要在上面的 getBLEDeviceCharacteristics 接口中获取
characteristicId: that.data.writeCharacteristicId,
// 这里的value是ArrayBuffer类型
value: buffer,
// value: arrayBuffer,
success: function (res) {
if (count != 0) {
that.writeFuction(that, data, count, size)
} else {
wx.showToast({
title: '发送成功',
icon: 'success',
duration: 2000
})
that.setData({
block: "block",
block1: "none"
})
}
},
complete: function (res) {
console.log(res);
}
})
count--;
return 0;
},
关于cpcl介绍
exports.val = "! 0 200 200 1030 1\r\n" +
"PAGE - WIDTH 576\r\n" +
"UNDERLINE OFF\r\n" +
"SETBOLD 1\r\n" +
"SETMAG 2 2\r\n" +
"T 20 0 0 25 HC慧驰速递\r\n" +
"UNDERLINE OFF\r\n" +
"SETBOLD 1\r\n" +
"SETMAG 1 1\r\n" +
"{df}"+
"T 25 0 445 950 已验视\r\n" +
"UNDERLINE OFF\r\n" +
"SETBOLD 0\r\n" +
"SETMAG 1 1\r\n" +
"LINE 0 1000 566 1000 4\r\n" +
// "FORM\r\n"+
"PRINT\r\n";