使用PyV8在Python爬虫中执行js代码

前言

可能很多人会觉得这是一个奇葩的需求，爬虫去好好的爬数据不就行了，解析js干嘛？吃饱了撑的？

搜索一下互联网上关于这个问题还真不少，但是大多数童鞋是因为自己的js基础太烂，要么是HTML基础烂，要么ajax基础烂，反正各方面都很烂。基础这么渣不好好去学基础写什么爬虫？

那你肯定要问了“请问我的朋友，你TM怎么也有这个需求？莫非你是个技术渣？”

非也非也，博主作为一个拥有3年多前端经验的攻城尸，怎么会被这个问题给难倒呢，老夫今天遇到的问题很显然没有那么简单。

问题

那么博主到底是遇到什么问题了呢？

博主今天要去爬一个接口，但是调用那个接口需要带上令牌，也就是存储在Cookie中的一个类似token的东西，Cookie的值是一段js生成的，这段js又是通过另外一个接口获取回来的，而获取回来的js代码还是动态的，WTF！！！开发人员你这是 弄撒嘞？

路人甲：我擦嘞，声称经验老道的博主不会分析js的逻辑？

对，我就是不会，特么的js代码都是混淆加密的，眼睛都看瞎了都特么不知道写的都是写啥？

算了，我直接执行拿到结果就好了，管他写的是什么鬼。

思路

理一理思路，现在要做的事情其实很简单

1. 请求接口A，拿到动态生成的混淆过的js代码
2. 执行js代码，拿到生成的cookie值
3. 请求接口B，带上js生成的令牌
4. 拿到结果，愉快的玩耍...
   

思路相当的清晰，感觉秒秒钟就可以实现了呢。（）

难题

Python里面执行js？有点意思，我干嘛不用nodejs呢？

因为Python是世界上最屌的语言啊！没有之一！

找到了PyV8这个神奇的模块，机器已经有了pip，执行安装一下不就OK了？

pip install pyv8

不要怀疑，博主机器装的是 Kali Linux ，Root 权限，不需要 sudo

接着报错

pip install -U PyV8
Collecting PyV8
 Using cached PyV8-0.5.zip
Building wheels for collected packages: PyV8
 Running setup.py bdist_wheel for PyV8 ... error
 Complete output from command /usr/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-QUm4bX/PyV8/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" bdist_wheel -d /tmp/tmpb0udlepip-wheel- --python-tag cp27:
 running bdist_wheel
 running build
 running build_py
 creating build
 creating build/lib.linux-x86_64-2.7
 copying PyV8.py -> build/lib.linux-x86_64-2.7
 running build_ext
 building '_PyV8' extension
 creating build/temp.linux-x86_64-2.7
 creating build/temp.linux-x86_64-2.7/src
 x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fno-strict-aliasing -Wdate-time -D_FORTIFY_SOURCE=2 -g -fdebug-prefix-map=/build/python2.7-cFt4xx/python2.7-2.7.12=. -fstack-protector-strong -Wformat -Werror=format-security -fPIC -DBOOST_PYTHON_STATIC_LIB -Ilib/python/inc -Ilib/boost/inc -Ilib/v8/inc -I/usr/include/python2.7 -c src/Exception.cpp -o build/temp.linux-x86_64-2.7/src/Exception.o
 cc1plus: warning: command line option ‘-Wstrict-prototypes' is valid for C/ObjC but not for C++
 In file included from src/Exception.cpp:1:0:
 src/Exception.h:6:16: fatal error: v8.h: 没有那个文件或目录
 #include <v8.h>
     ^
 compilation terminated.
 error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
 
 ----------------------------------------
 Failed building wheel for PyV8
 Running setup.py clean for PyV8
Failed to build PyV8
Installing collected packages: PyV8
 Running setup.py install for PyV8 ... error
 Complete output from command /usr/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-QUm4bX/PyV8/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-7OAwUa-record/install-record.txt --single-version-externally-managed --compile:
 running install
 running build
 running build_py
 creating build
 creating build/lib.linux-x86_64-2.7
 copying PyV8.py -> build/lib.linux-x86_64-2.7
 running build_ext
 building '_PyV8' extension
 creating build/temp.linux-x86_64-2.7
 creating build/temp.linux-x86_64-2.7/src
 x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fno-strict-aliasing -Wdate-time -D_FORTIFY_SOURCE=2 -g -fdebug-prefix-map=/build/python2.7-cFt4xx/python2.7-2.7.12=. -fstack-protector-strong -Wformat -Werror=format-security -fPIC -DBOOST_PYTHON_STATIC_LIB -Ilib/python/inc -Ilib/boost/inc -Ilib/v8/inc -I/usr/include/python2.7 -c src/Exception.cpp -o build/temp.linux-x86_64-2.7/src/Exception.o
 cc1plus: warning: command line option ‘-Wstrict-prototypes' is valid for C/ObjC but not for C++
 In file included from src/Exception.cpp:1:0:
 src/Exception.h:6:16: fatal error: v8.h: 没有那个文件或目录
  #include <v8.h>
     ^
 compilation terminated.
 error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
 
 ----------------------------------------
Command "/usr/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-QUm4bX/PyV8/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-7OAwUa-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /tmp/pip-build-QUm4bX/PyV8/

似乎是因为缺少 v8.h 这个文件导致的，可是又看不懂啥意思。

解决

通过搜索引擎找到了解决方案，原来是因为 PyV8 依赖于Boost ，然而这个问题官方并没有说，所以得先安装下这个包

apt-get update && apt-get install libboost-all-dev

安装完成之后继续安装 PyV8 ，依然是上面同样的问题，看来只能手动来了。

下载 https://github.com/emmetio/pyv8-binaries

解压并选择合适自己系统环境的文件，再次解压 并把解压得到的文件复制到

/usr/lib/python2.7/dist-packages/

里面去，然后测试看是否成功，终端执行

python
import PyV8

如果没有报错，那就成功了，开始愉快的玩耍，下面是我需要解析的js代码

var l = [119, 98, 115, 33, 111, 109, 120, 105, 118, 62, 92, 50, 50, 54, 45, 50, 50, 51, 45, 50, 50, 55, 45, 50, 49, 58, 45, 50, 50, 49, 45, 50, 51, 51, 45, 50, 50, 52, 45, 50, 50, 51, 45, 50, 50, 54, 45, 50, 49, 55, 45, 50, 49, 58, 45, 50, 49, 50, 45, 50, 50, 54, 45, 50, 50, 58, 45, 50, 50, 49, 45, 50, 50, 51, 45, 50, 50, 58, 45, 50, 51, 51, 45, 50, 50, 58, 45, 50, 50, 55, 45, 50, 50, 54, 45, 50, 50, 54, 94, 60, 119, 98, 115, 33, 121, 119, 99, 100, 108, 62, 92, 49, 45, 51, 50, 45, 53, 45, 55, 45, 50, 50, 45, 57, 45, 56, 45, 50, 51, 45, 51, 45, 51, 49, 45, 50, 52, 45, 50, 54, 45, 50, 49, 45, 50, 57, 45, 52, 45, 58, 45, 50, 53, 45, 50, 56, 45, 54, 45, 50, 55, 45, 50, 58, 45, 50, 94, 60, 119, 98, 115, 33, 118, 62, 35, 35, 60, 103, 112, 115, 33, 41, 119, 62, 49, 60, 119, 61, 121, 119, 99, 100, 108, 47, 109, 102, 111, 104, 117, 105, 60, 119, 44, 44, 42, 124, 118, 44, 62, 84, 117, 115, 106, 111, 104, 47, 103, 115, 112, 110, 68, 105, 98, 115, 68, 112, 101, 102, 41, 111, 109, 120, 105, 118, 92, 121, 119, 99, 100, 108, 92, 119, 94, 94, 42, 126, 60, 37, 47, 100, 112, 112, 108, 106, 102, 41, 40, 114, 117, 112, 108, 102, 111, 40, 45, 118, 45, 124, 113, 98, 117, 105, 59, 40, 48, 40, 126, 42, 60];
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