uniapp蓝牙传输中文乱码问题

问题描述：app接收到蓝牙传出过来的二进制数据，1.app进行arrbuff转成16进制字符串

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

2.将16进制的字符串转成10进制字符串这里需要特别注意（JS默认是Unicode编码的也就是UTF-16）你看下你的设备传输过来的是什么编码

// 16进制转字符串
async function hexCharCodeToStr(hex) {
    var arr = hex.split(""),
        out = "",
        len = hex.length / 2;
    for (var i = 0; i < len; i++) {
        out += String.fromCharCode(parseInt(hex.substr(i * 2, 2), 16));
    }
    // 此时的out为UTF-8
    //蓝牙使用的是UTF-8编码
    // 解决乱码问题 （JS默认是Unicode编码的 也就是UTF-16）
    return await utf8to16(out)
}

3.解决中文乱码关键【这里以我自己举例，我对接的设备传输的编码是utf-8】我需要把UTF-8编码转成UTF-16下面提供两个方法

function utf8to16(str) {
    var out, i, len, c;
    var char2, char3;
    out = "";
    len = str.length;
    i = 0;
    while (i < len) {
        c = str.charCodeAt(i++);
        switch (c >> 4) {
            case 0:
            case 1:
            case 2:
            case 3:
            case 4:
            case 5:
            case 6:
            case 7:
                // 0xxxxxxx
                out += str.charAt(i - 1);
                break;
            case 12:
            case 13:
                // 110x xxxx 10xx xxxx
                char2 = str.charCodeAt(i++);
                out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
                break;
            case 14:
                // 1110 xxxx 10xx xxxx 10xx xxxx
                char2 = str.charCodeAt(i++);
                char3 = str.charCodeAt(i++);
                out += String.fromCharCode(((c & 0x0F) << 12) |
                    ((char2 & 0x3F) << 6) |
                    ((char3 & 0x3F) << 0));
                break;
        }
    }
    return out;
}

function utf16to8(str) {
    var out, i, len, c;
    out = "";
    len = str.length;
    for(i = 0; i < len; i++) {
    c = str.charCodeAt(i);
    if ((c >= 0x0001) && (c <= 0x007F)) {
    out += str.charAt(i);
    } else if (c > 0x07FF) {
    out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
    out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
    out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
    } else {
    out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
    out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
    }
    }
    return out;
}

4，APP蓝牙发送数据给设备需要注意（因为js默认时utf-16的需要转成utf-8）在进行发送，否则设备端也解析不了

// 字符串转16进制 str需要传入设备需要的utf-8（js字符串默认是Unicode编码utf16，需转成设备的utf8）解决中文问题,否则设备处理不了
function strToHexCharCode(str) {
if (str === "")
return "";
var hexCharCode = [];
// hexCharCode.push("0x");
for (var i = 0; i < str.length; i++) {
hexCharCode.push((str.charCodeAt(i)).toString(16));
}
return hexCharCode.join("");
}

5.调用发送数据给设备

//设置wifi
            setWifiInfo() {
                uni.showLoading({
                    title: 'wifi网络配置中..',
                    mask: false
                });
                //此时需要注意 wifi名为中文需要把中文的utf-16转成utf-8
                let body = {
                    "ssid":that.$lizhao.scale.utf16to8(that.picker.form.ssid),
                    "password": that.picker.form.password
                }
                let length = that.$lizhao.scale.switch_sl(JSON.stringify(body).length, 16) // 十进制转十六进制
                let stri = '0'
                for (let i = 0; i < (7 - length.length); i++) {
                    stri += '0'
                }
                let cmd = '0002' //2转成两位的16进制为00 02
                let len = stri + length //body的长度为39转成4位的16进制为00 00 00 26
                //十进制数据转换为16进制
                let body_16 = that.$lizhao.scale.strToHexCharCode(JSON.stringify(body))
                let hex = that.Bluetooth.agreement.magic + cmd + that.Bluetooth.agreement.id + len + body_16
                let arr = that.splitArr(hex)
                //多个指令串行发送，并行可能会失败
                that.writeCmd(arr, 0)
            },
            //arr为hex分割的数组，i为当前数组下标
            async writeCmd(arr, i) {
                let res = await that.$lizhao.bluetooth.writeBLECharacteristicValue(arr[i])
                if (res == 'writeBLECharacteristicValue:ok') {
                    i++
                    if (i > arr.length) {
                        return
                    }
                    that.writeCmd(arr, i)
                } else {
                    that.writeCmd(arr, i)
                }

            },
            //分割指令每20位分割一下，返回数组
            splitArr(hex) {
                let arr = []
                for (let a = 0; a < Math.ceil(hex.length / 20); a++) {
                    let str = hex.slice(a * 20, a * 20 + 20)
                    arr.push(str)
                }
                return arr
            }