python网络爬虫（1）——安装scrapy框架的常见问题及其解决方法

　　Scrapy是为了爬取网站数据而编写的一款应用框架，出名，强大。所谓的框架其实就是一个集成了相应的功能且具有很强通用性的项目模板。

　　其实在Linux和 Mac安装，就简单的pip命令即可：

pip install wheel

　　但是在Windows上安装却有很多坑，所以下面小编讲一下自己在windows10安装及配置Scrapy中遇到的一些坑及其解决的方法，现在总结如下，希望对大家有所帮助。

　　包的下载地址：https://www.lfd.uci.edu/~gohlke/pythonlibs/

常见问题一：pip版本需要升级

       如果你的pip版本比较老，可能在安装的过程中需要更新对应的pip版本，所以最好通过指令升级一下pip

       升级指令如下（这是在cmd中操作）：

python -m pip install  --upgrade  pip

　　升级完成后，这一类问题就解决了。

常见问题二：安装wheel

pip install  wheel

        如果未安装wheel，使用该命令可以直接安装wheel，如果已经安装了，使用该命令则会显示如下图所出信息，不会重复进行安装

Requirement already satisfied: wheel in d:python3libsite-packages

常见问题三：缺少lxml

          顺利安装完成wheel，到这里对应的.whl文件，注意别改文件名，然后下载如下的xlml文件,我们可以在LFD中下载对应版本的lxml，如下（我的是windows 64位操作系统，python版本是3.6）

 　　下载之后，进入cmd命令行安装好对应的whl文件：

pip install lxml-4.1.1-cp36-cp36m-win_amd64.whl

       未安装的，可以直接安装，已经安装的会出现如下代码表示成功

Requirement already satisfied: lxml==4.1.1 from file:///D:/lxml-4.1.1-cp36-cp36m-win_amd64.whl in d:python3libsite-packages

常见问题四：路径冲突

Error in sitecustomize; set PYTHONVERBOSE for traceback:
AttributeError: module 'sys' has no attribute 'setdefaultencoding'

　　因为sys.path 中多了python27的site-package冲突　　

　　到“…／local/lib/python3.6/site-packages/“目录下（目录因人而已），删除里面的路径即可

python -v homebrew.pth

常见问题五：缺少Twisted

       安装Twisted，然后根据自己的电脑安装（我的是python 3.6,操作系统是64位，名称中间的cp36是python3.6的意思，amd64是python的位数）

 下载好后，安装命令如下：

 pip install  Twisted-17.9.0-cp36-cp36m-win_amd64.whl

未安装的，可以直接安装，安装的则显示成功，如下：

Successfully installed Twisted-17.9.0

常见问题六：出现UnicodeDecodeError

（由于小编已经踩过坑了，所以这些代码都是网上找到的相似代码，大体内容相似，问题一致）

Exception:
  Traceback (most recent call last):
    File "c:program filespython36libsite-packagespipcompat\__init__.py", line 73, in console_to_str
      return s.decode(sys.__stdout__.encoding)
 UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb6 in position 34: invalid start byte
 
 During handling of the above exception, another exception occurred:
 
 Traceback (most recent call last):
   File "c:program filespython36libsite-packagespipasecommand.py", line 215, in main
     status = self.run(options, args)
   File "c:program filespython36libsite-packagespipcommandsinstall.py", line 342, in run
     prefix=options.prefix_path,
   File "c:program filespython36libsite-packagespip
eq
eq_set.py", line 784, in install
     **kwargs
   File "c:program filespython36libsite-packagespip
eq
eq_install.py", line 878, in install
     spinner=spinner,
   File "c:program filespython36libsite-packagespiputils\__init__.py", line 676, in call_subprocess
     line = console_to_str(proc.stdout.readline())
   File "c:program filespython36libsite-packagespipcompat\__init__.py", line 75, in console_to_str
     return s.decode('utf_8')
 UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb6 in position 34: invalid start byte

　　　或者下面error：

Exception:
Traceback (most recent call last):
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespipcompat\__init__.py", line 73, in console_to_str
    return s.decode(sys.__stdout__.encoding)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb6 in position 34: invalid start byte

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespipcommandsinstall.py", line 342, in run
    prefix=options.prefix_path,
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip
eq
eq_set.py", line 784, in install
    **kwargs
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip
eq
eq_install.py", line 878, in install
    spinner=spinner,
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespiputils\__init__.py", line 676, in call_subprocess
    line = console_to_str(proc.stdout.readline())
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespipcompat\__init__.py", line 75, in console_to_str
    return s.decode('utf_8')
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb6 in position 34: invalid start byte

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespipcommandsinstall.py", line 385, in run
    requirement_set.cleanup_files()
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip
eq
eq_set.py", line 729, in cleanup_files
    req.remove_temporary_source()
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip
eq
eq_install.py", line 977, in remove_temporary_sou
    rmtree(self.source_dir)
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendor
etrying.py", line 49, in wrapped_f
    return Retrying(*dargs, **dkw).call(f, *args, **kw)
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendor
etrying.py", line 212, in call
    raise attempt.get()
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendor
etrying.py", line 247, in get
    six.reraise(self.value[0], self.value[1], self.value[2])
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendorsix.py", line 686, in reraise
    raise value
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendor
etrying.py", line 200, in call
    attempt = Attempt(fn(*args, **kwargs), attempt_number, False)
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespiputils\__init__.py", line 102, in rmtree
    onerror=rmtree_errorhandler)
  File "c:users59740appdatalocalprogramspythonpython36libshutil.py", line 488, in rmtree
    return _rmtree_unsafe(path, onerror)
  File "c:users59740appdatalocalprogramspythonpython36libshutil.py", line 387, in _rmtree_unsafe
    onerror(os.rmdir, path, sys.exc_info())
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespiputils\__init__.py", line 114, in rmtree_errorhandler
    func(path)
PermissionError: [WinError 32] 另一个程序正在使用此文件，进程无法访问。: 'C:\Users\59740\AppData\Local\Temp\pip-build-1djzmudb\scrapy'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespipasecommand.py", line 215, in main
    status = self.run(options, args)
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespipcommandsinstall.py", line 385, in run
    requirement_set.cleanup_files()
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespiputilsuild.py", line 38, in __exit__
    self.cleanup()
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespiputilsuild.py", line 42, in cleanup
    rmtree(self.name)
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendor
etrying.py", line 49, in wrapped_f
    return Retrying(*dargs, **dkw).call(f, *args, **kw)
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendor
etrying.py", line 212, in call
    raise attempt.get()
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendor
etrying.py", line 247, in get
    six.reraise(self.value[0], self.value[1], self.value[2])
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendorsix.py", line 686, in reraise
    raise value
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespip\_vendor
etrying.py", line 200, in call
    attempt = Attempt(fn(*args, **kwargs), attempt_number, False)
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespiputils\__init__.py", line 102, in rmtree
    onerror=rmtree_errorhandler)
  File "c:users59740appdatalocalprogramspythonpython36libshutil.py", line 488, in rmtree
    return _rmtree_unsafe(path, onerror)
  File "c:users59740appdatalocalprogramspythonpython36libshutil.py", line 378, in _rmtree_unsafe
    _rmtree_unsafe(fullname, onerror)
  File "c:users59740appdatalocalprogramspythonpython36libshutil.py", line 387, in _rmtree_unsafe
    onerror(os.rmdir, path, sys.exc_info())
  File "c:users59740appdatalocalprogramspythonpython36libsite-packagespiputils\__init__.py", line 114, in rmtree_errorhandler
    func(path)
PermissionError: [WinError 32] 另一个程序正在使用此文件，进程无法访问。: 'C:\Users\59740\AppData\Local\Temp\pip-build-1djzmudb\scrapy

　　

解决方法：

　　打开 

c:program filespython36libsite-packagespipcompat\__init__.py 

 　　找到

return s.decode('utf_8')

并将其改为

return s.decode('cp936')

  
这个是编码问题，虽然py3统一用utf-8了。但windows下的终端显示用的还是gbk编码。

 常见问题七：缺少win32

　　缺少模块，会显示如下错误：

ModuleNotFoundError: No module named 'win32api'

　　安装win32，然后根据自己的电脑安装（我的是python 3.6,操作系统是64位，名称中间的cp36是python3.6的意思，amd64是python的位数）

　　安装指令如下：

pip install pywin32-221-cp36-cp36m-win_amd64.whl

最后安装scrapy

　　在cmd中输入如下代码

pip install scrapy

　　 ok，终于经过折腾完成这个scrapy框架的安装，真的是经历九九八十一难。

　　现在总结一下安装scrapy的大致顺序：

基本一个好的anaconda环境，我们安装以下面顺序即可：

1，pip install wheel

2，下载对应版本的twisted，然后  pip install   下载好的框架.whl

3，pip install pywin32

4，pip install scrapy

　　

复杂问题：找不到指定模组

　　报错如下：

 　　网上找了很多方法，都没有解决，很烦。

　　于是我将安装的东西全部卸载，依次卸载lxml，twisted，pywin32。如果运气好的话，再次安装就OK了。

　　如果运气不好的话，我们需要更新一个东西，那就是openssl的版本。

conda install openssl=1.0.2p

　　这样就OK了。

　　参考： https://www.cnblogs.com/little-orangeaaa/p/10259973.html

scrapy框架常见命令

　　查看所有命令

scrapy -h

　　查看帮助信息

scapy --help

　　查看版本信息

(venv)ql@ql:~$ scrapy version
Scrapy 1.1.2
(venv)ql@ql:~$ 
(venv)ql@ql:~$ scrapy version -v
Scrapy    : 1.1.2
lxml      : 3.6.4.0
libxml2   : 2.9.4
Twisted   : 16.4.0
Python    : 2.7.12 (default, Jul  1 2016, 15:12:24) - [GCC 5.4.0 20160609]
pyOpenSSL : 16.1.0 (OpenSSL 1.0.2g-fips  1 Mar 2016)
Platform  : Linux-4.4.0-36-generic-x86_64-with-Ubuntu-16.04-xenial
(venv)ql@ql:~$ 

　　新建一个工程

scrapy startproject spider_name

　　构建爬虫genspider(generator spider)（一个工程中可以存在多个spider, 但是名字必须唯一）

scrapy genspider name domain
#如:
#scrapy genspider sohu sohu.org

　　查看当前项目内有多少爬虫

scrapy list

　　view使用浏览器打开网页

scrapy view http://www.baidu.com

　　shell命令, 进入scrpay交互环境

#进入该url的交互环境
scrapy shell http://www.dmoz.org/Computers/Programming/Languages/Python/Books/

　　之后便进入交互环境，我们主要使用这里面的response命令, 例如可以使用

response.xpath()    #括号里直接加xpath路径

　　runspider命令用于直接运行创建的爬虫, 并不会运行整个项目

scrapy runspider 爬虫名称