C#实现谷歌翻译API

　　由于谷歌翻译官方API是付费版本，本着免费和开源的精神，分享一下用C#实现谷歌翻译API的代码。这个代码非常简单，主要分两块：通过WebRequest的方式请求内容；获取Get方式的请求参数（难点在于tk的获取）。注意该项目需要添加以下几个引用：

System.Web

Newtonsoft.Json

MSScriptControl(com组件中的Microsoft Script Control 1.0)

一、WebRequest代码

var webRequest = WebRequest.Create(url) as HttpWebRequest;

webRequest.Method = "GET";

webRequest.CookieContainer = cookie;

webRequest.Referer = referer;

webRequest.Timeout = 20000;

webRequest.Headers.Add("X-Requested-With:XMLHttpRequest");

webRequest.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";

webRequest.UserAgent = useragent;

  using (var webResponse = (HttpWebResponse)webRequest.GetResponse())
  {
　　 using (var reader = new StreamReader(webResponse.GetResponseStream(), Encoding.UTF8))
　　 {

　　　　html = reader.ReadToEnd();
　　　　reader.Close();
　　　　webResponse.Close();
　　 }
  }

　　

二、谷歌翻译接口的实现

　　1、抓包查看翻译网络请求，这里是用谷歌浏览器查看的网络请求，如下图：

 　　可以看到，请求方式是“Get”方式，后面跟的请求参数很多，如下图：

　　其中，最重要的参数有：sl--来源语言，一般设置为auto即自动检测，tl--目标语言，你想翻译成的语言，tk--ticket即使发车车票，谷歌就靠这个来防止我们免费调用的，这是本API最难的地方。

　　2、tk的获取

　　在打开https://translate.google.com/页面是，获取到的HTML代码中有如下一个TKK的值：

　　直接在获取的源代码中用正则匹配出这个值：Regex re = new Regex(@"(?<=TKK=')(.*?)(?=')")，可以得到一个字符串：428502.368022592

　　从监控的网络中可以发现其中一个JS调用了这个TKK值，这个JS加了密进行混淆的，要破解这个JS需要扎实的基本功，以及足够的耐心，我也是网上找的别人破解的JS代码，亲测可用，需将此代码保存在gettk.js文档中，方便调用：

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)
}

　　

　　要得到tk只需要，运行tk这个函数，它有两个输入值：a为翻译文本内容，TKK是上文正则匹配得到的JS字符串执行的结果值。为方便在C#中执行JS，封装了一个能执行JS的函数，如下：

        /// <summary>
        /// 执行JS
        /// </summary>
        /// <param name="sExpression">参数体</param>
        /// <param name="sCode">JavaScript代码的字符串</param>
        /// <returns></returns>
        private string ExecuteScript(string sExpression, string sCode)
        {
            MSScriptControl.ScriptControl scriptControl = new MSScriptControl.ScriptControl();
            scriptControl.UseSafeSubset = true;
            scriptControl.Language = "JScript";
            scriptControl.AddCode(sCode);
            try
            {
                string str = scriptControl.Eval(sExpression).ToString();
                return str;
            }
            catch (Exception ex)
            {
                string str = ex.Message;
            }
            return null;
        }      

　　

　　3、实现翻译的完整代码

using System;
using System.IO;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;
using MSScriptControl;
using System.Web;

namespace GoogleTranslate
{
    public class Translate
    {
        /// <summary>
        /// 谷歌翻译
        /// </summary>
        /// <param name="text">待翻译文本</param>
        /// <param name="fromLanguage">自动检测：auto</param>
        /// <param name="toLanguage">中文：zh-CN，英文：en</param>
        /// <returns>翻译后文本</returns>
        public string GoogleTranslate(string text, string fromLanguage, string toLanguage)
        {
            CookieContainer cc = new CookieContainer();

            string GoogleTransBaseUrl = "https://translate.google.com/";

            var BaseResultHtml = GetResultHtml(GoogleTransBaseUrl, cc, "");

            Regex re = new Regex(@"(?<=TKK=')(.*?)(?=')");

            var TKK = re.Match(BaseResultHtml).ToString();//在返回的HTML中正则匹配TKK的值

            var GetTkkJS = File.ReadAllText("./gettk.js");

            var tk = ExecuteScript("tk("" + text + "","" + TKK + "")", GetTkkJS);

            string googleTransUrl = "https://translate.google.com/translate_a/single?client=t&sl=" + fromLanguage + "&tl=" + toLanguage + "&hl=en&dt=at&dt=bd&dt=ex&dt=ld&dt=md&dt=qca&dt=rw&dt=rm&dt=ss&dt=t&ie=UTF-8&oe=UTF-8&otf=1&ssel=0&tsel=0&kc=1&tk=" + tk + "&q=" + HttpUtility.UrlEncode(text);

            var ResultHtml = GetResultHtml(googleTransUrl, cc, "https://translate.google.com/");

            dynamic TempResult = Newtonsoft.Json.JsonConvert.DeserializeObject(ResultHtml);

            string ResultText = Convert.ToString(TempResult[0][0][0]);

            return ResultText;
        }

        public string GetResultHtml(string url, CookieContainer cookie, string referer)
        {
            var html = "";

            var webRequest = WebRequest.Create(url) as HttpWebRequest;

            webRequest.Method = "GET";

            webRequest.CookieContainer = cookie;

            webRequest.Referer = referer;

            webRequest.Timeout = 20000;

            webRequest.Headers.Add("X-Requested-With:XMLHttpRequest");

            webRequest.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";

            webRequest.UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36";

            using (var webResponse = (HttpWebResponse)webRequest.GetResponse())
            {
                using (var reader = new StreamReader(webResponse.GetResponseStream(), Encoding.UTF8))
                {

                    html = reader.ReadToEnd();
                    reader.Close();
                    webResponse.Close();
                }
            }
            return html;
        }

        /// <summary>
        /// 执行JS
        /// </summary>
        /// <param name="sExpression">参数体</param>
        /// <param name="sCode">JavaScript代码的字符串</param>
        /// <returns></returns>
        private string ExecuteScript(string sExpression, string sCode)
        {
            MSScriptControl.ScriptControl scriptControl = new MSScriptControl.ScriptControl();
            scriptControl.UseSafeSubset = true;
            scriptControl.Language = "JScript";
            scriptControl.AddCode(sCode);
            try
            {
                string str = scriptControl.Eval(sExpression).ToString();
                return str;
            }
            catch (Exception ex)
            {
                string str = ex.Message;
            }
            return null;
        }
    }
}