Failed building wheel for Twisted
在安装scrapy框架的过程中，pip install scrapy 出现报错信息：
building 'twisted.test.raiser' extension
error: Microsoft Visual C++ 14.0 is required. Get it with "Microsoft Visual C++ Build Tools": http://landinghub.visualstudio.com/visual-cpp-build-tools
解决方法：
网址：https://www.lfd.uci.edu/~gohlke/pythonlibs/#twisted
选择 与自己电脑python版本相关的Twisted。下载保存到本地。
然后执行pip install xx\xx\Twisted‑17.9.0‑cp36‑cp36m‑win_amd64.whl
执行结果如图所示：
(jobbole) D:\virtualenv>pip install D:\virtualenv\jobbole\Scripts\Twisted-17.9.0-cp36-cp36m-win_amd64.whl Processing d:\virtualenv\jobbole\scripts\twisted-17.9.0-cp36-cp36m-win_amd64.whl Requirement already satisfied: incremental>=16.10.1 in d:\virtualenv\jobbole\lib\site-packages (from Twisted==17.9.0) Requirement already satisfied: zope.interface>=4.0.2 in d:\virtualenv\jobbole\lib\site-packages (from Twisted==17.9.0) Requirement already satisfied: Automat>=0.3.0 in d:\virtualenv\jobbole\lib\site-packages (from Twisted==17.9.0) Requirement already satisfied: constantly>=15.1 in d:\virtualenv\jobbole\lib\site-packages (from Twisted==17.9.0) Requirement already satisfied: hyperlink>=17.1.1 in d:\virtualenv\jobbole\lib\site-packages (from Twisted==17.9.0) Requirement already satisfied: setuptools in d:\virtualenv\jobbole\lib\site-packages (from zope.interface>=4.0.2->Twisted==17.9.0) Requirement already satisfied: six in d:\virtualenv\jobbole\lib\site-packages (from Automat>=0.3.0->Twisted==17.9.0) Requirement already satisfied: attrs in d:\virtualenv\jobbole\lib\site-packages (from Automat>=0.3.0->Twisted==17.9.0) Requirement already satisfied: idna>=2.5 in d:\virtualenv\jobbole\lib\site-packages (from hyperlink>=17.1.1->Twisted==17.9.0) Installing collected packages: Twisted Successfully installed Twisted-17.9.0
然后，顺利安装scrapy
(jobbole) D:\virtualenv>pip install scrapy
