利用Node中間層，對接訊飛實現h5頁面文章tts（自動朗讀）功能

很多時候在看文章的時候都會有自動朗讀文章內容的功能，那麼這種功能如何在h5上是怎麼實現的呢，下面就拿我司一個基本需求作爲線索，看是怎麼一步一步實現的

需求提出

經過我司產品經理的想法，做出如下功能
1.自動朗讀當前h5頁面文章

競品——》

調研發現，競品h5是app原生實現，而我司都是h5實現文章閱讀，所以開始進行h5的調研

對接科大訊飛在線語音合成

調研發現科大訊飛的在線語音合成可以基本提供相應功能，決定做一個demo來測試效果

1.控制檯開通權限

2.閱讀文檔

具體代碼如下

import axios from 'axios'
import * as md5 from './md5'

axios.defaults.withCredentials = true

let Appid = 'xxxxx'
let apiKey = 'xxxxxx'
let CurTime = Date.parse(new Date()) / 1000
let param = {
    auf: 'audio/L16;rate=16000',
    aue: 'lame',
    voice_name: 'xiaoyan',
    speed: '50',
    volume: '50',
    pitch: '50',
    engine_type: 'intp65',
    text_type: 'text'
}
let Base64 = {
    encode: (str) => {
        return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g,
            function toSolidBytes(match, p1) {
                return String.fromCharCode('0x' + p1);
            }));
    },
    decode: (str) => {
        // Going backwards: from bytestream, to percent-encoding, to original string.
        return decodeURIComponent(atob(str).split('').map(function (c) {
            return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2);
        }).join(''));
    }
}
let xp = Base64.encode(JSON.stringify(param))
let CheckSum = md5.hex_md5(apiKey + CurTime + xp)

let headers = {
  'X-Appid': Appid,
  'X-CurTime': CurTime,
  'X-Param': xp,
  'X-CheckSum': CheckSum,
  'Content-Type': 'application/x-www-form-urlencoded; charset=utf-8'
}

export function getAloud (text) {
    // let data = {
    //   text: encodeURI(text)
    // }
    var formdata = new FormData()
    formdata.append('text', text)
    return axios({
        baseURL: window.location.href.includes('demo') ? 'https://api.xfyun.cn' : '/tts',
        method: 'POST',
        url: '/v1/service/v1/tts',
        headers: {
          ...headers
        },
        data: formdata
    })
}

經過測試，是返回二進制文件流了但是前端試了各種辦法沒有實現流的播放

node中間層

引入node中間層是考慮到文件可以存儲，可以放到cdn上進行緩存，可以減少相似文章的請求科大訊飛接口，可以減少流量的產生，所以決定加入node中間層

ps：考拉閱讀有node服務器作爲一些中間層的處理。主要技術棧是node + koa2 + pm2

const md5 = require('../lib/md5.js')
const fs = require('fs')
const path = require('path')
const marked = require('marked')
const request = require('request')


let Appid = ''
let apiKey = ''
let CurTime
let param = {
    auf: 'audio/L16;rate=16000',
    aue: 'lame',
    voice_name: 'x_yiping',
    speed: '40',
    volume: '50',
    pitch: '50',
    engine_type: 'intp65',
    text_type: 'text'
}

var b = new Buffer(JSON.stringify(param));
let xp = b.toString('base64')
let CheckSum

let headers

exports.getAloud = async ctx => {
    CurTime = Date.parse(new Date()) / 1000
    CheckSum = md5.hex_md5(apiKey + CurTime + xp)
    headers = {
        'X-Appid': Appid,
        'X-CurTime': CurTime,
        'X-Param': xp,
        'X-CheckSum': CheckSum,
        'Content-Type': 'application/x-www-form-urlencoded; charset=utf-8'
    }
    let id = ctx.request.body.id
    let text = ctx.request.body.text
    console.log(ctx.query)
    var postData = {
        text: text
    }
    let r = request({
        url: 'http://api.xfyun.cn/v1/service/v1/tts',   // 請求的URL
        method: 'POST',                   // 請求方法
        headers: headers,
        formData: postData
    }, function (error, response, body) {
        // console.log('error:', error); // Print the error if one occurred
        // console.log('statusCode:', response && response.statusCode); // Print the response status code if a response was received
        // console.log('body:', body); // Print the HTML for the Google homepage.
    })
    await new Promise((resolve, reject) => {
        let filePath = path.join(__dirname, 'public/') + `/${id}.mp3`
        const upStream = fs.createWriteStream(filePath)
        r.pipe(upStream)
        upStream.on('close', () => {
            console.log('download finished');
            resolve()
        });
    })
    .then((res) => {
        ctx.body = {
            code: 200,
            message: '語音合成成功',
            data: {
                url: 'https://fe.koalareading.com/file/' + id + '.mp3'
            }
        }
    })
}

主要運用request的管道流概念
把後臺返回的二進制文件導入到流裏面，在寫入到文件裏面
最後返回一個url給前端播放使用

此致，測試

//返回url。相同文章唯一id區分，可以緩存使用
https://fe.koalareading.com/file/1112.mp3

需求demo完成