百度翻译爬虫-Web版(自动生成sign)

 # 面向对象
 # 百度翻译 -- 网页版(自动获取token,sign)
 import requests
 import js2py
 import json
 import re

 class WebFanyi:
     """百度翻译网页版爬虫"""
     def __init__(self,query_str):
         self.session = requests.session()
         headers = {
             "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36",
         }
         self.session.headers = headers
         self.baidu_url = "https://www.baidu.com/"
         self.root_url = "https://fanyi.baidu.com/"
         self.lang_url = "https://fanyi.baidu.com/langdetect"
         self.trans_url = "https://fanyi.baidu.com/v2transapi"
         self.query_str = query_str

     def get_token_gtk(self):
         '''获取token和gtk(用于合成Sign)'''
         self.session.get(self.root_url)
         resp = self.session.get(self.root_url)
         html_str = resp.content.decode()
         token = re.findall(r"token: '(.*?)'", html_str)[0]
         gtk = re.findall(r"window.gtk = '(.*?)'", html_str)[0]
         return token,gtk

     def generate_sign(self,gtk):
         """生成sign"""
         # 1. 准备js编译环境
         context = js2py.EvalJs()
         with open('webtrans.js', encoding='utf8') as f:
             js_data = f.read()
             js_data = re.sub("window\[l\]",'"'+gtk+'"',js_data)
             # js_data = re.sub("window\[l\]", "\"{}\"".format(gtk), js_data)
             # print(js_data)
             context.execute(js_data)
         sign = context.e(self.query_str)
         return sign

     def lang_detect(self):
         '''获取语言转换类型.eg: zh-->en'''
         lang_resp = self.session.post(self.lang_url,data={"query":self.query_str})
         lang_json_str = lang_resp.content.decode()  # {"error":0,"msg":"success","lan":"zh"}
         lan = json.loads(lang_json_str)['lan']
         to = "en" if lan == "zh" else "zh"
         return lan,to

     def parse_url(self,post_data):
         trans_resp = self.session.post(self.trans_url,data=post_data)
         trans_json_str = trans_resp.content.decode()
         trans_json = json.loads(trans_json_str)
         result = trans_json["trans_result"]["data"][0]["dst"]
         print("{}: {}".format(self.query_str,result))

     def run(self):
         """实现逻辑"""
         # 1.获取百度的cookie,(缺乏百度首页的cookie会始终报错998)
         self.session.get(self.baidu_url)
         # 2. 获取百度翻译的token和gtk(用于合成sign)
         token, gtk = self.get_token_gtk()
         # 3. 生成sign
         sign = self.generate_sign(gtk)
         # 4. 获取语言转换类型.eg: zh-->en
         lan, to = self.lang_detect()
         # 5. 发送请求,获取响应,输出结果
         post_data = {
             "from": lan,
             "to": to,
             "query": self.query_str,
             "transtype": "realtime",
             "simple_means_flag": 3,
             "sign": sign,
             "token": token
         }
         self.parse_url(post_data)

 if __name__ == '__main__':
     webfanyi = WebFanyi('lover')
     webfanyi.run()

上述代码中用于生成sign的 webtrans.js 文件具体代码如下(可以自己抓包,在js中打断点获取):

 // webtrans.js

 function n(r, o) {
     for (var t = 0; t < o.length - 2; t += 3) {
         var a = o.charAt(t + 2);
         a = a >= "a" ? a.charCodeAt(0) - 87 : Number(a),
         a = "+" === o.charAt(t + 1) ? r >>> a : r << a,
         r = "+" === o.charAt(t) ? r + a & 4294967295 : r ^ a
     }
     return r
 }
 function e(r) {
     var o = r.match(/[\uD800-\uDBFF][\uDC00-\uDFFF]/g);
     if (null === o) {
         var t = r.length;
         t > 30 && (r = "" + r.substr(0, 10) + r.substr(Math.floor(t / 2) - 5, 10) + r.substr(-10, 10))
     } else {
         for (var e = r.split(/[\uD800-\uDBFF][\uDC00-\uDFFF]/), C = 0, h = e.length, f = []; h > C; C++)
             "" !== e[C] && f.push.apply(f, a(e[C].split(""))),
             C !== h - 1 && f.push(o[C]);
         var g = f.length;
         g > 30 && (r = f.slice(0, 10).join("") + f.slice(Math.floor(g / 2) - 5, Math.floor(g / 2) + 5).join("") + f.slice(-10).join(""))
     }
     var u = void 0
       ,
         // l = "" + String.fromCharCode(103) + String.fromCharCode(116) + String.fromCharCode(107);
         i = null;
         u = null !== i ? i : (i = window[l] || "") || "";
     for (var d = u.split("."), m = Number(d[0]) || 0, s = Number(d[1]) || 0, S = [], c = 0, v = 0; v < r.length; v++) {
         var A = r.charCodeAt(v);
         128 > A ? S[c++] = A : (2048 > A ? S[c++] = A >> 6 | 192 : (55296 === (64512 & A) && v + 1 < r.length && 56320 === (64512 & r.charCodeAt(v + 1)) ? (A = 65536 + ((1023 & A) << 10) + (1023 & r.charCodeAt(++v)),
         S[c++] = A >> 18 | 240,
         S[c++] = A >> 12 & 63 | 128) : S[c++] = A >> 12 | 224,
         S[c++] = A >> 6 & 63 | 128),
         S[c++] = 63 & A | 128)
     }
     for (var p = m, F = "" + String.fromCharCode(43) + String.fromCharCode(45) + String.fromCharCode(97) + ("" + String.fromCharCode(94) + String.fromCharCode(43) + String.fromCharCode(54)), D = "" + String.fromCharCode(43) + String.fromCharCode(45) + String.fromCharCode(51) + ("" + String.fromCharCode(94) + String.fromCharCode(43) + String.fromCharCode(98)) + ("" + String.fromCharCode(43) + String.fromCharCode(45) + String.fromCharCode(102)), b = 0; b < S.length; b++)
         p += S[b],
         p = n(p, F);
     return p = n(p, D),
     p ^= s,
     0 > p && (p = (2147483647 & p) + 2147483648),
     p %= 1e6,
     p.toString() + "." + (p ^ m)
 }

实际上,除了用js2py作为python中执行js代码的环境编译器外,还可以使用另一个方法 'execjs' ,不过要先通过 pip install PyExecJS 安装PyExecJS模块.具体实现代码如下:

 import execjs
 with open("webtrans.js") as f:
     js_data = f.read()
     js_data = re.sub("window\[l\]", '"' + gtk + '"', js_data)
     sign = execjs.compile(js_data).call("e", query_str)  # 调用webtrans.js代码中的 e函数，传入参数为 query_str
     print(sign)