測試通過時間：2019-8-20
參閱：C#實現谷歌翻譯API、Python之Google翻譯爬蟲

首先宣告，沒有什麼不良動機，因為經常會用 translate.google.cn，就想著用 Python 模擬網頁提交實現文件的批量翻譯。據說有 API，可是要收費。

生成 Token

Google 為防爬蟲而生成 token 的程式碼是 Javascript 的，且是根據網站的 TKK 值和提交的文字動態生成。更新規律未知，只好定時去取一下了。

網上能找到的 Python 程式碼大部分是去呼叫 PyExecJS 庫，先不說執行效率的高低（大概是差一個數量級），首先是捨近求遠，不純粹，本人不喜歡。

好不容易找到了一段 Python 程式碼還有點小 Bug，且缺少動態獲取 TKK 的步驟。最後還是對照 Javascript 程式碼自己改成 Python 了。方法很簡單，先轉成易懂的 Javascript，再轉成 Python。Javascript 程式碼來自C#實現谷歌翻譯API。

原始（晦澀） Javascript 程式碼

var b = function (a, b) {
    for (var d = 0; d < b.length - 2; d += 3) {
        var c = b.charAt(d + 2),
            c = "a" <= c ? c.charCodeAt(0) - 87 : Number(c),
            c = "+" == b.charAt(d + 1) ? a >>> c : a << c;
        a = "+" == b.charAt(d) ? a + c & 4294967295 : a ^ c
    }
    return a
}
 
var tk =  function (a,TKK) {
    for (var e = TKK.split("."), h = Number(e[0]) || 0, g = [], d = 0, f = 0; f < a.length; f++) {
        var c = a.charCodeAt(f);
        128 > c ? g[d++] = c : (2048 > c ? g[d++] = c >> 6 | 192 : (55296 == (c & 64512) && f + 1 < a.length && 56320 == (a.charCodeAt(f + 1) & 64512) ? (c = 65536 + ((c & 1023) << 10) + (a.charCodeAt(++f) & 1023), g[d++] = c >> 18 | 240, g[d++] = c >> 12 & 63 | 128) : g[d++] = c >> 12 | 224, g[d++] = c >> 6 & 63 | 128), g[d++] = c & 63 | 128)
    }
    a = h;
    for (d = 0; d < g.length; d++) a += g[d], a = b(a, "+-a^+6");
    a = b(a, "+-3^+b+-f");
    a ^= Number(e[1]) || 0;
    0 > a && (a = (a & 2147483647) + 2147483648);
    a %= 1E6;
    return a.toString() + "." + (a ^ h)
}
 

易懂的 Javascript 程式碼

function RL(a, b) {
    for (var d = 0; d < b.length - 2; d += 3) {
        var c = b.charAt(d + 2);
        c = "a" <= c ? c.charCodeAt(0) - 87 : Number(c);
        c = "+" == b.charAt(d + 1) ? a >>> c : a << c;
        a = "+" == b.charAt(d) ? a + c & 4294967295 : a ^ c;
    }
    return a
}
 
function TL(a,TKK) {
    var e = TKK.split(".");
    var h = Number(e[0]) || 0;
    var g = [];
    var d = 0;
    for (var f = 0; f < a.length; f++) {
        var c = a.charCodeAt(f);
        if (128 > c)
        {
            g[d++] = c;
        } 
        else
        {
            if (2048 > c)
            {
                g[d++] = c >> 6 | 192;
            }
            else
            {
                if (55296 == (c & 64512) && f + 1 < a.length && 56320 == (a.charCodeAt(f + 1) & 64512))
                {
                    c = 65536 + ((c & 1023) << 10) + (a.charCodeAt(++f) & 1023);
                    g[d++] = c >> 18 | 240;
                    g[d++] = c >> 12 & 63 | 128;
                }
                else
                {
                    g[d++] = c >> 12 | 224;
                    g[d++] = c >> 6 & 63 | 128;
                }
            }
            g[d++] = c & 63 | 128;
        }
    }
    a = h;
    for (var d = 0; d < g.length; d++) {
        a += g[d];
        a = b(a, "+-a^+6");
    }
    a = b(a, "+-3^+b+-f");
    a ^= Number(e[1]) || 0;
    0 > a && (a = (a & 2147483647) + 2147483648);
    a %= 1E6;
    return a.toString() + "." + (a ^ h)
}
 

Python 程式碼

def getGoogleToken(a, TKK):
    def RL(a, b):
        for d in range(0, len(b)-2, 3):
            c = b[d + 2]
            c = ord(c[0]) - 87 if 'a' <= c else int(c)
            c = a >> c if '+' == b[d + 1] else a << c
            a = a + c & 4294967295 if '+' == b[d] else a ^ c
        return a

    g = []
    f = 0
    while f < len(a):
        c = ord(a[f])
        if 128 > c:
            g.append(c)
        else:
            if 2048 > c:
                g.append((c >> 6) | 192)
            else:
                if (55296 == (c & 64512)) and (f + 1 < len(a)) and (56320 == (ord(a[f+1]) & 64512)):
                    f += 1
                    c = 65536 + ((c & 1023) << 10) + (ord(a[f]) & 1023)
                    g.append((c >> 18) | 240)
                    g.append((c >> 12) & 63 | 128)
                else:
                    g.append((c >> 12) | 224)
                    g.append((c >> 6) & 63 | 128)
            g.append((c & 63) | 128)
        f += 1

    e = TKK.split('.')
    h = int(e[0]) or 0
    t = h
    for item in g:
        t += item
        t = RL(t, '+-a^+6')
    t = RL(t, '+-3^+b+-f')
    t ^= int(e[1]) or 0
    if 0 > t:
        t = (t & 2147483647) + 2147483648
    result = t % 1000000
    return str(result) + '.' + str(result ^ h)

獲取 Token Key

Google 的 TKK 可以通過訪問網站 https://translate.google.cn 獲取，裡面有段腳本里包含了“tkk:('xxxxxx.xxxxxx')”，用正則表示式擷取即可。

    res = requests.get('https://translate.google.cn', timeout = 3)
    res.raise_for_status()
    result = re.search(r'tkk\:\'(\d+\.\d+)?\'', res.text).group(1)

劃分文章段落

因為常從 PDF 裡複製文字翻譯，這樣就不能依賴換行符來劃分段落了。只能判斷空行，作為段落的分界。

另外 Google 返回的結果 Json 裡，會以英文句點作為分隔符，每一句譯文均作為陣列的一項分開。所以最後得合併一下，成為一個段落。

完整程式碼

程式碼不長，全文黏貼如下。
GoogleTranslator.py：

import requests
import re
import json
import time

class GoogleTranslator ():
    _host = 'translate.google.cn'

    _headers = {
        'Host': _host,
        'User-Agent': 'Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Mobile Safari/537.36',
        'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
        'Accept-Language': 'zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3',
        'Accept-Encoding': 'gzip, deflate, br',
        'Content-Type': 'application/x-www-form-urlencoded;charset=utf-8',
        'Referer': 'https://' + _host,
        'Connection': 'keep-alive',
        'Cache-Control': 'max-age=0'
    }

    _language = {
        'afrikaans': 'af',
        'arabic': 'ar',
        'belarusian': 'be',
        'bulgarian': 'bg',
        'catalan': 'ca',
        'czech': 'cs',
        'welsh': 'cy',
        'danish': 'da',
        'german': 'de',
        'greek': 'el',
        'english': 'en',
        'esperanto': 'eo',
        'spanish': 'es',
        'estonian': 'et',
        'persian': 'fa',
        'finnish': 'fi',
        'french': 'fr',
        'irish': 'ga',
        'galician': 'gl',
        'hindi': 'hi',
        'croatian': 'hr',
        'hungarian': 'hu',
        'indonesian': 'id',
        'icelandic': 'is',
        'italian': 'it',
        'hebrew': 'iw',
        'japanese': 'ja',
        'korean': 'ko',
        'latin': 'la',
        'lithuanian': 'lt',
        'latvian': 'lv',
        'macedonian': 'mk',
        'malay': 'ms',
        'maltese': 'mt',
        'dutch': 'nl',
        'norwegian': 'no',
        'polish': 'pl',
        'portuguese': 'pt',
        'romanian': 'ro',
        'russian': 'ru',
        'slovak': 'sk',
        'slovenian': 'sl',
        'albanian': 'sq',
        'serbian': 'sr',
        'swedish': 'sv',
        'swahili': 'sw',
        'thai': 'th',
        'filipino': 'tl',
        'turkish': 'tr',
        'ukrainian': 'uk',
        'vietnamese': 'vi',
        'yiddish': 'yi',
        'chinese_simplified': 'zh-CN',
        'chinese_traditional': 'zh-TW',
        'auto': 'auto'
    }
    _url = 'https://' + _host + '/translate_a/single'
    _params = {
            'client': 'webapp',
            'sl': 'en',
            'tl': 'zh-CN',
            'hl': 'zh-CN',
            'dt': 'at',
            'dt': 'bd',
            'dt': 'ex',
            'dt': 'ld',
            'dt': 'md',
            'dt': 'qca',
            'dt': 'rw',
            'dt': 'rm',
            'dt': 'ss',
            'dt': 't',
            'otf': '1',
            'ssel': '0',
            'tsel': '0',
            'kc': '1'
    }

    __cookies = None

    __googleTokenKey = '376032.257956'
    __googleTokenKeyUpdataTime = 600.0
    __googleTokenKeyRetireTime = time.time() + 600.0

    def __init__(self, src = 'en', dest = 'zh-CN', tkkUpdataTime = 600.0):
        if src not in self._language and src not in self._language.values():
            src = 'auto'
        if dest not in self._language and dest not in self._language.values():
            dest = 'auto'
        self._params['sl'] = src
        self._params['tl'] = dest
        self.googleTokenKeyUpdataTime = tkkUpdataTime
        self.__updateGoogleTokenKey()

    def __updateGoogleTokenKey(self):
        self.__googleTokenKey = self.__getGoogleTokenKey()
        self.__googleTokenKeyRetireTime = time.time() + self.__googleTokenKeyUpdataTime

    def __getGoogleTokenKey(self):
        """Get the Google TKK from https://translate.google.cn"""
        # TKK example: '435075.3634891900'
        result = ''
        try:
            res = requests.get('https://' + self._host, timeout = 3)
            res.raise_for_status()
            self.__cookies = res.cookies
            result = re.search(r'tkk\:\'(\d+\.\d+)?\'', res.text).group(1)
        except requests.exceptions.ReadTimeout as ex:
            print('ERROR: ' + str(ex))
            time.sleep(1)
        return result

    def __getGoogleToken(self, a, TKK):
        """Calculate Google tk from TKK """
        # https://www.cnblogs.com/chicsky/p/7443830.html
        # if text = 'Tablet Developer' and TKK = '435102.3120524463', then tk = '315066.159012'

        def RL(a, b):
            for d in range(0, len(b)-2, 3):
                c = b[d + 2]
                c = ord(c[0]) - 87 if 'a' <= c else int(c)
                c = a >> c if '+' == b[d + 1] else a << c
                a = a + c & 4294967295 if '+' == b[d] else a ^ c
            return a

        g = []
        f = 0
        while f < len(a):
            c = ord(a[f])
            if 128 > c:
                g.append(c)
            else:
                if 2048 > c:
                    g.append((c >> 6) | 192)
                else:
                    if (55296 == (c & 64512)) and (f + 1 < len(a)) and (56320 == (ord(a[f+1]) & 64512)):
                        f += 1
                        c = 65536 + ((c & 1023) << 10) + (ord(a[f]) & 1023)
                        g.append((c >> 18) | 240)
                        g.append((c >> 12) & 63 | 128)
                    else:
                        g.append((c >> 12) | 224)
                        g.append((c >> 6) & 63 | 128)
                g.append((c & 63) | 128)
            f += 1

        e = TKK.split('.')
        h = int(e[0]) or 0
        t = h
        for item in g:
            t += item
            t = RL(t, '+-a^+6')
        t = RL(t, '+-3^+b+-f')
        t ^= int(e[1]) or 0
        if 0 > t:
            t = (t & 2147483647) + 2147483648
        result = t % 1000000
        return str(result) + '.' + str(result ^ h)


    def translate(self, text):
        if time.time() > self.__googleTokenKeyRetireTime:
            self.__updateGoogleTokenKey()
        data = {'q': text}
        self._params['tk'] = self.__getGoogleToken(text, self.__googleTokenKey)
        result = ''
        try:
            res = requests.post(self._url,
                            headers = self._headers,
                            cookies = self.__cookies,
                            data = data,
                            params = self._params,
                            timeout = 6)
            res.raise_for_status()
            jsonText = res.text
            if len(jsonText)>0:
                jsonResult = json.loads(jsonText)
                if len(jsonResult[0])>0:
                    for item in jsonResult[0]:
                        result += item[0]
            return result
        except Exception as ex:
            print('ERROR: ' + str(ex))
            return ''


import time
from GoogleTranslator import GoogleTranslator

def readFile(fileName):
    with open(fileName, 'r') as f:
        paragraph = ''
        for line in f:
            if line[0]!='\n':
                paragraph += line.strip('\n')
            else:
                if len(paragraph)>0:
                    yield paragraph
                    paragraph = ''
        if len(paragraph)>0:
            yield paragraph

main.py：

def main():
    translator = GoogleTranslator()
    count = 0
    with open('C:\\dx\\python\\d.txt', 'w', encoding='utf-8') as df:
        for line in readFile('C:\\dx\\python\\s.txt'):
            if len(line) > 1:
                count += 1
                print('\r' + str(count), end = '', flush = True)
                df.write(line.strip() + "\n")
                result = translator.translate(line)
                df.write(result.strip() + "\n\n")

if __name__ == "__main__":
    startTime = time.time()
    main()
    print()
    print('%.2f seconds' % (time.time() - startTime))

結束語

求人不如求己。不能怕煩，程式碼都是人敲出來的，找不到現成的還得靠自己編