熱敏藍牙印表機開發

最近在做小票打印這塊，項目需求是IOS和安卓兩種都要實現，開始做的時候也是一臉懵，然後網上找了不少資料，踩了一堆坑，看了好多文章，結果還好成了
藍牙打印機一般分為兩種打印模式，票據打印、標籤打印

公司買的渣渣打印機連開發文檔都沒有，害我走了不少坑，讓我開發買的時候也不諮詢諮詢我
目前微信小程序連接藍牙打印機 wx.createBLEConnection 測試在IOS設備上沒有問題，在部分安卓手機上會出現異常（表現為，連接是會彈出系統配對框，不管點取消還是輸入配對碼後點確定，都會立馬斷開連接。如果不輸入也不取消則會在30秒以內自動斷開藍牙打印機）

現在採用的方式是各給安卓和IOS寫一套藍牙打印的命令
IOS

// ====================藍牙操作================== //初始化藍牙模組 openBluetoothAdapter() {

if (app.sysinfo.provider == 1) {
    // 開啟藍牙
    app.onBluetooth()
    setTimeout(() => {
        this.android\_search()
    }, 2000)
    return false;
}


this.closeBluetoothAdapter()
uni.openBluetoothAdapter({
    success: (res) => {
        console.log("初始化藍牙模組: " + JSON.stringify(res));
        this.startBluetoothDevicesDiscovery()
    },
    fail: (res) => {
        if (res.errCode === 10001) {
            uni.onBluetoothAdapterStateChange((res) => {
                console.log('監聽藍牙適配器狀態變化事件', 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('初始化藍牙失敗，錯誤碼：' + res.errCode)
            return false;
        }
        app.alert(res.errMsg)
    }
})

//取得本機藍牙適配器狀態 getBluetoothAdapterState() { uni.getBluetoothAdapterState({ success: (res) => { console.log(‘取得本機藍牙適配器狀態。’, JSON.stringify(res)) if (res.discovering) { this.onBluetoothDeviceFound() } else if (res.available) { this.startBluetoothDevicesDiscovery() } }, fail: (res) => { console.log(’error:取得本機藍牙適配器狀態失敗’, JSON.stringify(res)) setTimeout(() => { this.getBluetoothAdapterState() }, 500) } }) },

//開始搜尋附近的藍牙週邊設備 startBluetoothDevicesDiscovery() { console.log(this.discoveryStarted); if (this.discoveryStarted) { return } console.log(‘開始搜索藍牙設備’); 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(‘當前藍牙適配器不可用’) } else { app.alert(‘搜索藍牙失敗,狀態碼：’ + res.errCode) } } }) }, 500)

// 停止搜索 stopBluetoothDevicesDiscovery() { uni.stopBluetoothDevicesDiscovery() this.discoveryStarted = false },

//尋找到新設備的事件的回調函數 onBluetoothDeviceFound() { console.log(‘尋找到新設備的事件的回調函數’); 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 }

    })
})

//連接低功耗藍牙設備 createBLEConnection(e) { uni.showLoading({ title: ‘設備連接中’, 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('已配對')
    }

    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('檢測到設備未連接，嘗試連接....');
        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()
        // 防止獲取失敗
        setTimeout(() => {
            this.getBLEDeviceServices(deviceId)
        }, 1000)
    },
    fail: (res) => {
        uni.hideLoading();
        app.Toast('設備連接失敗')
        console.log("藍牙連接失敗:", res);
    }
})
this.stopBluetoothDevicesDiscovery()

//取得藍牙設備所有服務(service) getBLEDeviceServices(deviceId) { uni.getBLEDeviceServices({ deviceId, success: (res) => { console.log(“取得藍牙服務成功：” + JSON.stringify(res)) if (res.services.length == 0) { uni.hideLoading(); app.alert(‘沒有取得藍牙服務，無法打印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(“取得藍牙服務失敗：” + JSON.stringify(res)) } }) },

//取得藍牙設備某個服務中所有特徵值(characteristic) getBLEDeviceCharacteristics(deviceId, serviceId) { console.log(‘取得藍牙設備某個服務中所有特徵值’, deviceId, serviceId) uni.getBLEDeviceCharacteristics({ deviceId, serviceId, success: (res) => { console.log(‘取得藍牙設備某個服務中所有特徵值 success’, JSON.stringify(res)) uni.hideLoading(); if (res.characteristics.length == 0) { app.alert(‘沒有取得藍牙服務，無法打印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('取得特徵值失敗：', res)
    }
})

// 操作之前先監聽，保證第一時間取得數據
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) => { // 該方法回調中可以用於處理連接意外斷開等異常情況 console.log(`藍牙連接狀態改變device ${res.deviceId} state has changed, connected: ${res.connected}`) if (res.connected == false) { app.global_printing = {} this.connected = false this.chs = [] this.canWrite = false } }) },

//斷開與低功耗藍牙設備的連接 closeBLEConnection() { app.global_printing = {} uni.closeBLEConnection({ deviceId: this.deviceId }) this.connected = false this.chs = [] this.canWrite = false },

//關閉藍牙模組 closeBluetoothAdapter() { app.global_printing = {} uni.closeBluetoothAdapter() this.discoveryStarted = false },

//發送數據 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(‘發送的數據：’ + bufferstr) // console.log(‘message發送成功’) }, fail: function(res) { fail(res) console.log(“數據發送失敗:” + JSON.stringify(res)) }, complete: function(res) { // console.log(“發送完成:” + JSON.stringify(res)) } }) },

//遍歷發送數據 printCode(arr) { var that = this; if (arr.length > 0) { this.sendStr(arr[0], function(success) { arr.shift(); that.printCode(arr); }, function(error) { app.alert(‘打印失敗，錯誤碼：’ + error.errCode) app.printing_status = false console.log(error); }); return false; }

setTimeout(function() {
    app.printing\_status = false
    console.log('打印結束');
}, 1000);

**Android
**就相對簡單方便，採用Native.js直接調用Native Java接口通道，通過plus.android調用安卓原生系統API。
原生安卓文檔 https://developer.android.google.cn/reference/android/bluetooth/BluetoothAdapter?hl=en

// ======================Android============ // 搜索藍牙設備 android_search(address = ‘’) { //搜索、配對 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(“開始搜索設備”); var filter = new IntentFilter(); var bdevice = new BluetoothDevice(); var on = null; var un = null; console.log(‘正在搜索請稍候’); BAdapter.startDiscovery(); //開啟搜索
var receiver; receiver = plus.android.implements(‘io.dcloud.android.content.BroadcastReceiver’, { onReceive: (context, intent) => { //實現onReceiver回調函數
plus.android.importClass(intent); //通過intent實例引入intent類，方便以後的‘.’操作
// console.log(intent.getAction()); //取得action
if (intent.getAction() == “android.bluetooth.adapter.action.DISCOVERY_FINISHED”) { main.unregisterReceiver(receiver); //取消監聽
console.log(“搜索結束”) } else { var BleDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); //判斷是否配對
if (BleDevice.getBondState() == bdevice.BOND_NONE) { console.log(“未配對藍牙設備：” + BleDevice.getName() + ’ ’ + BleDevice.getAddress()); //參數如果跟取得的mac地址一樣就配對
if (address == BleDevice.getAddress()) { if (BleDevice.createBond()) { //配對命令.createBond()
if (BleDevice.getName() != null) { console.log(“配對成功藍牙設備：” + BleDevice.getName() + ’ ’ + BleDevice.getAddress()); // app.Toast(“配對成功藍牙設備：” + BleDevice.getName()) } } else { console.log(‘配對失敗’) } } else { if (BleDevice.getName() != on) { //判斷防止重複添加
on = BleDevice.getName(); if (BleDevice.getName() != null) { this.devices.push({ deviceId: BleDevice.getAddress(), name: BleDevice.getName() }) console.log(“搜索到藍牙設備：” + BleDevice.getName() + ’ ’ + BleDevice.getAddress()); } } } } else { if (BleDevice.getName() != un) { //判斷防止重複添加
un = BleDevice.getName(); if (BleDevice.getName() != null) { this.devices.push({ deviceId: BleDevice.getAddress(), name: BleDevice.getName() + ’ (已配對)’, pair: true }) console.log(“已配對藍牙設備：” + 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); //註冊監聽

// 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('打印失敗')
    return false;
}


if (!bluetoothSocket.isConnected()) {
    console.log('檢測到設備未連接，嘗試連接....');
    bluetoothSocket.connect();
}

console.log('設備已連接');

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 //這裡關鍵  
    bluetoothSocket.close(); //必須關閉藍牙連接否則意外斷開的話打印錯誤  
}

setTimeout(function() {
    app.printing\_status = false
    console.log('打印結束');
}, 1000);

打印指令（更多打印指令參考 https://www.jianshu.com/p/dd6ca0054298）

/** * 復位打印機 */ public static final byte[] RESET = {0x1b, 0x40};

/** * 左對齊 */ public static final byte[] ALIGN_LEFT = {0x1b, 0x61, 0x00};

/** * 中間對齊 */ public static final byte[] ALIGN_CENTER = {0x1b, 0x61, 0x01};

/** * 右對齊 */ public static final byte[] ALIGN_RIGHT = {0x1b, 0x61, 0x02};

/** * 選擇加粗模式 */ public static final byte[] BOLD = {0x1b, 0x45, 0x01};

/** * 取消加粗模式 */ public static final byte[] BOLD_CANCEL = {0x1b, 0x45, 0x00};

/** * 寬高加倍 */ public static final byte[] DOUBLE_HEIGHT_WIDTH = {0x1d, 0x21, 0x11};

/** * 寬加倍 */ public static final byte[] DOUBLE_WIDTH = {0x1d, 0x21, 0x10};

/** * 高加倍 */ public static final byte[] DOUBLE_HEIGHT = {0x1d, 0x21, 0x01};

/** * 字體不放大 */ public static final byte[] NORMAL = {0x1d, 0x21, 0x00};

/** * 設置默認行間距 */ public static final byte[] LINE_SPACING_DEFAULT = {0x1b, 0x32};

關於二維碼的打印
通過上面的文章我們可以知道

我們需要讀取生成後的二維碼的像素點的rgba，再將圖片數據先4合1判斷0還是1(0代表打印1代表不打印)，緊接著八合1，因為一個字節有8位。最後使用打印機的位圖指令逐行掃描打印

4合1
本想著二維碼不是黑就是白，肯定不是255就是0，其實還是會有一小部分是其他數值的，這個要注意哦，每4位是一個像素點的rgba，然後黑白色的rgb就是(0,0,0)和(255,255,255)，所以每四位只把第一位黑白化，然後將每四位的第一位取出來作為新的數組，當rule>200的時候，值取0，表示不打印，否則取1，表示打印；

8合1
假如我們取出來的8位數是[0,0,0,0,0,0,0,1]，這個時候8合1，我們需要進行進制轉換，從右往左是2的零次方，2的一次方，等等，依次上加，實際是 0 * 27 + 0 * 26 + 0 * 25 + 0 * 24 + 0 * 23 + 0 * 22 + 0 * 21 + 1 * 20,這個數就是我們要的最終數據的其中之一。

將數據轉換成ArrayBuffer，其次打印必須要有指令！參考網址以及標準的ESC-POS指令集，下面代碼中的數字都是指令，另外，由於我這邊的打印機支持的是gb2312格式，所以在轉成ArrayBuffer的同時，還需要把編碼格式轉成正確的格式。

不過有一點我是要說下的，要注意ios和安卓的不同，安卓一次只能寫入不超過20字節（ios具體不清楚，目測120字節），建議是直接截取數據data.slice(20, byteLength)，打印成功再次回調，循環打印。

// 二維碼 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(() => { // 取得圖片數據 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’));

                // 二維碼
                for (let i = 0; i < buffer.byteLength; i = i + 120) {
                    that.arrPrint.push(buffer.slice(i, i + 120));
                }
                callback()
            }
        })
        // }, 3000);
    }
});

1、toArrayBuffer ,是個組件，要安裝的，https://www.npmjs.com/package/to-array-buffer 或者你用這種寫法也可以const buffer = new Uint8Array(Buffer.from(cmds, ‘gb2312’)).buffer;

2、注意查看自己的數據是否正確，畫圖的數據有問題的話，也可能打印出黑塊；

3、數據要算！！！要算！！要算！！，比如我畫圖是160*160 ，然後我打印數據拼接的指令[29, 118, 48, 0, 20, 0, 160, 0]這個裡面的20和160 這個就是算的，參考上方文章看下原因，大概就是1:8，然後畫圖和讀圖的數據一致

相關函數
（經過反復測試得出，打印紙一行最大字節數是32字節，這裡指的是普通的票據打印機）
打印三列或者兩列，是需要自己計算空格進行填充，沒有現成的指令噢
總寬度 - 左側文字長度 - 右側文字長度就是空格的長度。

/** * 打印兩列 * * @param leftText 左側文字 * @param rightText 右側文字 * @return */ printTwoData(leftText, rightText) { var sb = ’’ var leftTextLength = this.getBytesLength(leftText); var rightTextLength = this.getBytesLength(rightText); sb += leftText

// 計算兩側文字中間的空格
var marginBetweenMiddleAndRight = 32 - leftTextLength - rightTextLength;

for (var i = 0; i < marginBetweenMiddleAndRight; i++) {
    sb += ' '
}
sb += rightText
return sb.toString();

}, /** * 打印三列 * * @param leftText 左側文字 * @param middleText 中間文字 * @param rightText 右側文字 * @return */ printThreeData(leftText, middleText, rightText) { var sb = ’’ // 左邊最多顯示 8 個漢字 + 兩個點 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
// 計算左側文字和中間文字的空格長度
var marginBetweenLeftAndMiddle = 20 - leftTextLength - middleTextLength / 2;

for (var i = 0; i < marginBetweenLeftAndMiddle; i++) {
    sb += ' '
}
sb += middleText

// 計算右側文字和中間文字的空格長度
var marginBetweenMiddleAndRight = 12 - middleTextLength / 2 - rightTextLength;

for (var i = 0; i < marginBetweenMiddleAndRight; i++) {
    sb += ' '
}

sb += rightText

// 打印的時候發現，最右邊的文字總是偏右一個字符，所以需要刪除一個空格
// 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轉16進度字符串示例 ab2hex(buffer) { var hexArr = Array.prototype.map.call( new Uint8Array(buffer), function(bit) { return (‘00’ + bit.toString(16)).slice(-2) } ) return hexArr.join(’’); },

// 計算文字佔用長度 getBytesLength(str) { var num = str.length; //先用num保存一下字符串的長度（可以理解為：先假設每個字符都只佔用一個字節） for (var i = 0; i < str.length; i++) { //遍歷字符串 if (str.charCodeAt(i) > 255) { //判斷某個字符是否佔用兩個字節，如果是，num再+1 num++; } } return num; //返回最終的num，既是字符串總的字節長度 }

代碼大多是直接從項目中copy過來的，沒有整理過，並不能直接運行，僅供參考
不是我那一卷打印失敗的打印紙丟了，不然就讓你們看看什麼叫做第一次做打印機開發的程序員這次是真大乾貨，篇幅也很長，辛苦了我