最近在做小票打印这块，项目需求是IOS和安卓两种都要实现，开始做的时候也是一脸懵，然后网上找了不少资料，踩了一堆坑，看了好多文章，结果还好成了
蓝牙打印机一般分为两种打印模式，票据打印、标签打印
公司买的渣渣打印机连开发文档都没有，害我走了不少坑，让我开发买的时候也不咨询咨询我
目前微信小程序连接蓝牙打印机 wx.createBLEConnection 测试在IOS设备上没有问题，在部分安卓手机上会出现异常（表现为，连接是会弹出系统配对框，不管点取消还是输入配对码后点确定，都会立马断开连接。如果不输入也不取消则会在30秒以内自动断开蓝牙打印机）
现在采用的方式是各给安卓和IOS写一套蓝牙打印的命令
IOS
// ====================蓝牙操作================== //初始化蓝牙模块 openBluetoothAdapter() {
if (app.sysinfo.provider == 1) {
// 开启蓝牙
app.onBluetooth()
setTimeout(() => {
this.android\_search()
}, 2000)
return false;
}
this.closeBluetoothAdapter()
uni.openBluetoothAdapter({
success: (res) => {
console.log("初始化蓝牙模块: " + JSON.stringify(res));
this.startBluetoothDevicesDiscovery()
},
fail: (res) => {
if (res.errCode === 10001) {
uni.onBluetoothAdapterStateChange((res) => {
console.log('监听蓝牙适配器状态变化事件', res)
if (res.available == false) {
app.global\_printing = {}
this.connected = false
this.chs = \[\]
this.canWrite = false
}
if (res.available) {
this.startBluetoothDevicesDiscovery()
}
})
}
if (res.errCode) {
app.alert('初始化蓝牙失败，错误码：' + res.errCode)
return false;
}
app.alert(res.errMsg)
}
})
},
//获取本机蓝牙适配器状态 getBluetoothAdapterState() { uni.getBluetoothAdapterState({ success: (res) => { console.log(‘获取本机蓝牙适配器状态。’, JSON.stringify(res)) if (res.discovering) { this.onBluetoothDeviceFound() } else if (res.available) { this.startBluetoothDevicesDiscovery() } }, fail: (res) => { console.log(’error:获取本机蓝牙适配器状态失败’, JSON.stringify(res)) setTimeout(() => { this.getBluetoothAdapterState() }, 500) } }) },
//开始搜寻附近的蓝牙外围设备 startBluetoothDevicesDiscovery() { console.log(this.discoveryStarted); if (this.discoveryStarted) { return } console.log(‘开始搜索蓝牙设备’); this.discoveryStarted = true this.onBluetoothDeviceFound() setTimeout(() => { uni.startBluetoothDevicesDiscovery({ allowDuplicatesKey: true, success: (res) => { console.log(‘startBluetoothDevicesDiscovery success’, JSON.stringify( res)) }, fail: (res) => { if (res.errCode == ‘10001’) { app.alert(‘当前蓝牙适配器不可用’) } else { app.alert(‘搜索蓝牙失败,状态码：’ + res.errCode) } } }) }, 500)
},
// 停止搜索 stopBluetoothDevicesDiscovery() { uni.stopBluetoothDevicesDiscovery() this.discoveryStarted = false },
//寻找到新设备的事件的回调函数 onBluetoothDeviceFound() { console.log(‘寻找到新设备的事件的回调函数’); uni.onBluetoothDeviceFound((res) => { console.log(res); res.devices.forEach(device => { if (!device.name && !device.localName) { return } const foundDevices = this.devices const idx = this.inArray(foundDevices, ‘deviceId’, device.deviceId) if (idx === -1) { this.devices.push(device) } else { this.devices[idx] = device }
})
})
},
//连接低功耗蓝牙设备 createBLEConnection(e) { uni.showLoading({ title: ‘设备连接中’, mask: true });
const ds = e.currentTarget.dataset
const deviceId = ds.deviceId
const name = ds.name
if (app.sysinfo.provider == 1) {
if (ds.pair !== true) {
this.android\_search(deviceId)
} else {
console.log('已配对')
}
var device = null,
BAdapter = null,
BluetoothAdapter = null,
uuid = null,
main = null,
bluetoothSocket = null;
var mac\_address = deviceId
var main = plus.android.runtimeMainActivity();
BluetoothAdapter = plus.android.importClass("android.bluetooth.BluetoothAdapter");
var UUID = plus.android.importClass("java.util.UUID");
uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
BAdapter = BluetoothAdapter.getDefaultAdapter();
device = BAdapter.getRemoteDevice(mac\_address);
plus.android.importClass(device);
bluetoothSocket = device.createInsecureRfcommSocketToServiceRecord(uuid);
plus.android.importClass(bluetoothSocket);
if (!bluetoothSocket.isConnected()) {
console.log('检测到设备未连接，尝试连接....');
bluetoothSocket.connect();
}
this.connected = true
this.name = name
this.deviceId = deviceId
this.canWrite = true
app.global\_printing = {
name: name,
deviceId: deviceId
}
app.saveData1('global\_printing', app.global\_printing)
uni.hideLoading();
return false;
}
uni.createBLEConnection({
deviceId,
success: (res) => {
this.connected = true
this.name = name
this.deviceId = deviceId
app.global\_printing = {
name: name,
deviceId: deviceId
}
this.onBLEConnectionStateChange()
// 防止获取失败
setTimeout(() => {
this.getBLEDeviceServices(deviceId)
}, 1000)
},
fail: (res) => {
uni.hideLoading();
app.Toast('设备连接失败')
console.log("蓝牙连接失败:", res);
}
})
this.stopBluetoothDevicesDiscovery()
},
//获取蓝牙设备所有服务(service) getBLEDeviceServices(deviceId) { uni.getBLEDeviceServices({ deviceId, success: (res) => { console.log(“获取蓝牙服务成功：” + JSON.stringify(res)) if (res.services.length == 0) { uni.hideLoading(); app.alert(‘没有获取到蓝牙服务，无法打印001’) app.global_printing = {} return false } for (let i = 0; i < res.services.length; i++) { if (res.services[i].isPrimary) { this.getBLEDeviceCharacteristics(deviceId, res.services[i].uuid) return } } }, fail: (res) => { setTimeout(() => { this.getBLEDeviceServices(deviceId) }, 500) console.log(“获取蓝牙服务失败：” + JSON.stringify(res)) } }) },
//获取蓝牙设备某个服务中所有特征值(characteristic) getBLEDeviceCharacteristics(deviceId, serviceId) { console.log(‘获取蓝牙设备某个服务中所有特征值’, deviceId, serviceId) uni.getBLEDeviceCharacteristics({ deviceId, serviceId, success: (res) => { console.log(‘获取蓝牙设备某个服务中所有特征值 success’, JSON.stringify(res)) uni.hideLoading(); if (res.characteristics.length == 0) { app.alert(‘没有获取到蓝牙服务，无法打印002’) app.global_printing = {} return false } for (let i = 0; i < res.characteristics.length; i++) { let item = res.characteristics[i] if (item.properties.read) { uni.readBLECharacteristicValue({ deviceId, serviceId, characteristicId: item.uuid, }) } if (item.properties.write) { this.canWrite = true app.global_printing._deviceId = deviceId app.global_printing._serviceId = serviceId app.global_printing._characteristicId = item.uuid
app.saveData1('global\_printing', app.global\_printing)
//this.writeBLECharacteristicValue()
}
if (item.properties.notify || item.properties.indicate) {
uni.notifyBLECharacteristicValueChange({
deviceId,
serviceId,
characteristicId: item.uuid,
state: true,
})
}
}
},
fail(res) {
console.error('获取特征值失败：', res)
}
})
// 操作之前先监听，保证第一时间获取数据
uni.onBLECharacteristicValueChange((characteristic) => {
console.log(this.data.chs);
const idx = this.inArray(this.data.chs, 'uuid', characteristic.characteristicId)
const data = {}
if (idx === -1) {
this.chs\[this.data.chs.length\] = {
uuid: characteristic.characteristicId,
value: ab2hex(characteristic.value)
}
} else {
this.chs\[idx\] = {
uuid: characteristic.characteristicId,
value: ab2hex(characteristic.value)
}
}
})
},
onBLEConnectionStateChange() { uni.onBLEConnectionStateChange((res) => { // 该方法回调中可以用于处理连接意外断开等异常情况 console.log(`蓝牙连接状态改变device ${res.deviceId} state has changed, connected: ${res.connected}`) if (res.connected == false) { app.global_printing = {} this.connected = false this.chs = [] this.canWrite = false } }) },
//断开与低功耗蓝牙设备的连接 closeBLEConnection() { app.global_printing = {} uni.closeBLEConnection({ deviceId: this.deviceId }) this.connected = false this.chs = [] this.canWrite = false },
//关闭蓝牙模块 closeBluetoothAdapter() { app.global_printing = {} uni.closeBluetoothAdapter() this.discoveryStarted = false },
//发送数据 sendStr(bufferstr, success, fail) { var that = this; uni.writeBLECharacteristicValue({ deviceId: app.global_printing._deviceId, serviceId: app.global_printing._serviceId, characteristicId: app.global_printing._characteristicId, value: bufferstr, success: function(res) { success(res); console.log(‘发送的数据：’ + bufferstr) // console.log(‘message发送成功’) }, fail: function(res) { fail(res) console.log(“数据发送失败:” + JSON.stringify(res)) }, complete: function(res) { // console.log(“发送完成:” + JSON.stringify(res)) } }) },
//遍历发送数据 printCode(arr) { var that = this; if (arr.length > 0) { this.sendStr(arr[0], function(success) { arr.shift(); that.printCode(arr); }, function(error) { app.alert(‘打印失败，错误码：’ + error.errCode) app.printing_status = false console.log(error); }); return false; }
setTimeout(function() {
app.printing\_status = false
console.log('打印结束');
}, 1000);
},
**Android
**就相对简单方便，采用Native.js直接调用Native Java接口通道，通过plus.android调用安卓原生系统API。
原生安卓文档 https://developer.android.google.cn/reference/android/bluetooth/BluetoothAdapter?hl=en
// ======================Android============
// 搜索蓝牙设备
android_search(address = ‘’) {
//搜索、配对
var main = plus.android.runtimeMainActivity();
var IntentFilter = plus.android.importClass(‘android.content.IntentFilter’);
var BluetoothAdapter = plus.android.importClass(“android.bluetooth.BluetoothAdapter”);
var BluetoothDevice = plus.android.importClass(“android.bluetooth.BluetoothDevice”);
var BAdapter = BluetoothAdapter.getDefaultAdapter();
console.log(“开始搜索设备”);
var filter = new IntentFilter();
var bdevice = new BluetoothDevice();
var on = null;
var un = null;
console.log(‘正在搜索请稍候’);
BAdapter.startDiscovery(); //开启搜索
var receiver;
receiver = plus.android.implements(‘io.dcloud.android.content.BroadcastReceiver’, {
onReceive: (context, intent) => { //实现onReceiver回调函数
plus.android.importClass(intent); //通过intent实例引入intent类，方便以后的‘.’操作
// console.log(intent.getAction()); //获取action
if (intent.getAction() == “android.bluetooth.adapter.action.DISCOVERY_FINISHED”) {
main.unregisterReceiver(receiver); //取消监听
console.log(“搜索结束”)
} else {
var BleDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
//判断是否配对
if (BleDevice.getBondState() == bdevice.BOND_NONE) {
console.log(“未配对蓝牙设备：” + BleDevice.getName() + ’ ’ + BleDevice.getAddress());
//参数如果跟取得的mac地址一样就配对
if (address == BleDevice.getAddress()) {
if (BleDevice.createBond()) { //配对命令.createBond()
if (BleDevice.getName() != null) {
console.log(“配对成功蓝牙设备：” + BleDevice.getName() + ’ ’ +
BleDevice.getAddress());
// app.Toast(“配对成功蓝牙设备：” + BleDevice.getName())
}
} else {
console.log(‘配对失败’)
}
} else {
if (BleDevice.getName() != on) { //判断防止重复添加
on = BleDevice.getName();
if (BleDevice.getName() != null) {
this.devices.push({
deviceId: BleDevice.getAddress(),
name: BleDevice.getName()
})
console.log(“搜索到蓝牙设备：” + BleDevice.getName() + ’ ’ +
BleDevice.getAddress());
}
}
}
} else {
if (BleDevice.getName() != un) { //判断防止重复添加
un = BleDevice.getName();
if (BleDevice.getName() != null) {
this.devices.push({
deviceId: BleDevice.getAddress(),
name: BleDevice.getName() + ’ (已配对)’,
pair: true
})
console.log(“已配对蓝牙设备：” + BleDevice.getName() + ’ ’ + BleDevice.getAddress());
}
}
}
}
}
});
filter.addAction(bdevice.ACTION\_FOUND);
filter.addAction(BAdapter.ACTION\_DISCOVERY\_STARTED);
filter.addAction(BAdapter.ACTION\_DISCOVERY\_FINISHED);
filter.addAction(BAdapter.ACTION\_STATE\_CHANGED);
main.registerReceiver(receiver, filter); //注册监听
},
// 打印 android_printCode(arr) {
var that = this;
// 打印
var device = null,
BAdapter = null,
BluetoothAdapter = null,
uuid = null,
main = null,
bluetoothSocket = null;
var mac\_address = app.global\_printing.deviceId
var main = plus.android.runtimeMainActivity();
BluetoothAdapter = plus.android.importClass("android.bluetooth.BluetoothAdapter");
var UUID = plus.android.importClass("java.util.UUID");
uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
BAdapter = BluetoothAdapter.getDefaultAdapter();
try {
device = BAdapter.getRemoteDevice(mac\_address);
plus.android.importClass(device);
bluetoothSocket = device.createInsecureRfcommSocketToServiceRecord(uuid);
plus.android.importClass(bluetoothSocket);
} catch (e) {
console.log('asasssds-d=da=da-dsd');
app.printing\_status = false
app.alert('打印失败')
return false;
}
if (!bluetoothSocket.isConnected()) {
console.log('检测到设备未连接，尝试连接....');
bluetoothSocket.connect();
}
console.log('设备已连接');
if (bluetoothSocket.isConnected()) {
var outputStream = bluetoothSocket.getOutputStream();
plus.android.importClass(outputStream);
for (var i = 0; i < arr.length; i++) {
outputStream.write(arr\[i\]);
}
outputStream.flush();
device = null //这里关键
bluetoothSocket.close(); //必须关闭蓝牙连接否则意外断开的话打印错误
}
setTimeout(function() {
app.printing\_status = false
console.log('打印结束');
}, 1000);
},
打印指令（更多打印指令参考 https://www.jianshu.com/p/dd6ca0054298）
/** * 复位打印机 */ public static final byte[] RESET = {0x1b, 0x40};
/** * 左对齐 */ public static final byte[] ALIGN_LEFT = {0x1b, 0x61, 0x00};
/** * 中间对齐 */ public static final byte[] ALIGN_CENTER = {0x1b, 0x61, 0x01};
/** * 右对齐 */ public static final byte[] ALIGN_RIGHT = {0x1b, 0x61, 0x02};
/** * 选择加粗模式 */ public static final byte[] BOLD = {0x1b, 0x45, 0x01};
/** * 取消加粗模式 */ public static final byte[] BOLD_CANCEL = {0x1b, 0x45, 0x00};
/** * 宽高加倍 */ public static final byte[] DOUBLE_HEIGHT_WIDTH = {0x1d, 0x21, 0x11};
/** * 宽加倍 */ public static final byte[] DOUBLE_WIDTH = {0x1d, 0x21, 0x10};
/** * 高加倍 */ public static final byte[] DOUBLE_HEIGHT = {0x1d, 0x21, 0x01};
/** * 字体不放大 */ public static final byte[] NORMAL = {0x1d, 0x21, 0x00};
/** * 设置默认行间距 */ public static final byte[] LINE_SPACING_DEFAULT = {0x1b, 0x32};
关于二维码的打印
通过上面的文章我们可以知道
我们需要读取生成后的二维码的像素点的rgba，再将图片数据先4合1判断0还是1(0代表打印1代表不打印)，紧接着八合1，因为一个字节有8位。最后使用打印机的位图指令逐行扫描打印
4合1
本想着二维码不是黑就是白，肯定不是255就是0，其实还是会有一小部分是其他数值的，这个要注意哦，每4位是一个像素点的rgba，然后黑白色的rgb就是(0,0,0)和(255,255,255)，所以每四位只把第一位黑白化，然后将每四位的第一位取出来作为新的数组，当rule>200的时候，值取0，表示不打印，否则取1，表示打印；
8合1
假如我们取出来的8位数是[0,0,0,0,0,0,0,1]，这个时候8合1，我们需要进行进制转换，从右往左是2的零次方，2的一次方，等等，依次上加，实际是 0 * 27 + 0 * 26 + 0 * 25 + 0 * 24 + 0 * 23 + 0 * 22 + 0 * 21 + 1 * 20,这个数就是我们要的最终数据的其中之一。
将数据转换成ArrayBuffer，其次打印必须要有指令！参考网址以及标准的ESC-POS指令集，下面代码中的数字都是指令，另外，由于我这边的打印机支持的是gb2312格式，所以在转成ArrayBuffer的同时，还需要把编码格式转成正确的格式。
不过有一点我是要说下的，要注意ios和安卓的不同，安卓一次只能写入不超过20字节（ios具体不清楚，目测120字节），建议是直接截取数据data.slice(20, byteLength)，打印成功再次回调，循环打印。
// 二维码 qr(text,callback) { let that = this; const ctx = uni.createCanvasContext(‘myQrcode’); ctx.clearRect(0, 0, 240, 240); drawQrcode({ canvasId: ‘myQrcode’, text: String(text), width: 120, height: 120, callback(e) { // setTimeout(() => { // 获取图片数据 uni.canvasGetImageData({ canvasId: ‘myQrcode’, x: 0, y: 0, width: 240, height: 240, success(res) { let arr = that.convert4to1(res.data); let data = that.convert8to1(arr); const cmds = [].concat([27, 97, 1], [29, 118, 48, 0, 30, 0, 240, 0 ], data, [27, 74, 3], [27, 64]); const buffer = toArrayBuffer(Buffer.from(cmds, ‘gb2312’));
// 二维码
for (let i = 0; i < buffer.byteLength; i = i + 120) {
that.arrPrint.push(buffer.slice(i, i + 120));
}
callback()
}
})
// }, 3000);
}
});
},
1、toArrayBuffer ,是个组件，要安装的，https://www.npmjs.com/package/to-array-buffer 或者你用这种写法也可以const buffer = new Uint8Array(Buffer.from(cmds, ‘gb2312’)).buffer;
2、注意查看自己的数据是否正确，画图的数据有问题的话，也可能打印出黑块；
3、数据要算！！！要算！！要算！！ ，比如我画图是160*160 ，然后我打印数据拼接的指令[29, 118, 48, 0, 20, 0, 160, 0]这个里面的20和160 这个就是算的，参考上方文章看下原因，大概就是1:8，然后画图和读图的数据一致
相关函数
（经过反复测试得出，打印纸一行最大字节数是32字节，这里指的是普通的票据打印机）
打印三列或者两列，是需要自己计算空格进行填充，没有现成的指令噢
总宽度 - 左侧文字长度 - 右侧文字长度 就是空格的长度。
/** * 打印两列 * * @param leftText 左侧文字 * @param rightText 右侧文字 * @return */ printTwoData(leftText, rightText) { var sb = ’’ var leftTextLength = this.getBytesLength(leftText); var rightTextLength = this.getBytesLength(rightText); sb += leftText
// 计算两侧文字中间的空格
var marginBetweenMiddleAndRight = 32 - leftTextLength - rightTextLength;
for (var i = 0; i < marginBetweenMiddleAndRight; i++) {
sb += ' '
}
sb += rightText
return sb.toString();
}, /** * 打印三列 * * @param leftText 左侧文字 * @param middleText 中间文字 * @param rightText 右侧文字 * @return */ printThreeData(leftText, middleText, rightText) { var sb = ’’ // 左边最多显示 8 个汉字 + 两个点 if (leftText.length > 8) { leftText = leftText.substring(0, 8) + “..”; } var leftTextLength = this.getBytesLength(leftText); var middleTextLength = this.getBytesLength(middleText); var rightTextLength = this.getBytesLength(rightText);
sb += leftText
// 计算左侧文字和中间文字的空格长度
var marginBetweenLeftAndMiddle = 20 - leftTextLength - middleTextLength / 2;
for (var i = 0; i < marginBetweenLeftAndMiddle; i++) {
sb += ' '
}
sb += middleText
// 计算右侧文字和中间文字的空格长度
var marginBetweenMiddleAndRight = 12 - middleTextLength / 2 - rightTextLength;
for (var i = 0; i < marginBetweenMiddleAndRight; i++) {
sb += ' '
}
sb += rightText
// 打印的时候发现，最右边的文字总是偏右一个字符，所以需要删除一个空格
// sb.delete(sb.length() - 1, sb.length()).append(rightText);
return sb.toString();
},
max(n1, n2) { return Math.max(n1, n2) }, len(arr) { arr = arr || [] return arr.length },
//4合1 convert4to1(res) { let arr = []; for (let i = 0; i < res.length; i++) { if (i % 4 == 0) { let rule = 0.29900 * res[i] + 0.58700 * res[i + 1] + 0.11400 * res[i + 2]; if (rule > 200) { res[i] = 0; } else { res[i] = 1; } arr.push(res[i]); } } return arr; },
//8合1 convert8to1(arr) { let data = []; for (let k = 0; k < arr.length; k += 8) { let temp = arr[k] * 128 + arr[k + 1] * 64 + arr[k + 2] * 32 + arr[k + 3] * 16 + arr[k + 4] * 8 + arr[k + 5] * 4 + arr[k + 6] * 2 + arr[k + 7] * 1 data.push(temp); } return data; },
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 ab2hex(buffer) { var hexArr = Array.prototype.map.call( new Uint8Array(buffer), function(bit) { return (‘00’ + bit.toString(16)).slice(-2) } ) return hexArr.join(’’); },
// 计算文字占用长度 getBytesLength(str) { var num = str.length; //先用num保存一下字符串的长度（可以理解为：先假设每个字符都只占用一个字节） for (var i = 0; i < str.length; i++) { //遍历字符串 if (str.charCodeAt(i) > 255) { //判断某个字符是否占用两个字节，如果是，num再+1 num++; } } return num; //返回最终的num，既是字符串总的字节长度 }
代码大多是直接从项目中copy过来的，没有整理过，并不能直接运行，仅供参考
不是我那一卷打印失败的打印纸丢了，不然就让你们看看什么叫做 第一次做打印机开发的程序员这次是真大干货，篇幅也很长，辛苦了我