scrapy初体验 - 安装遇到的坑及第一个范例

scrapy，python开发的一个快速，高层次的屏幕抓取和web抓取框架，用于抓取web站点并从页面中提取结构化的数据。scrapy用途广泛，可以用于数据挖掘、监测和自动化测试。scrapy的安装稍显麻烦，不过按照以下步骤去进行，相信你也能很轻松的安装使用scrapy。

安装python2.7

scrapy1.0.3暂时只支持python2.7

# wget https://www.python.org/ftp/python/2.7.6/Python-2.7.6.tgz

[root@rocket software]# tar -zxvf Python-2.7.6.tgz    # 解压

[root@rocket software]# cd Python-2.7.6

[root@rocket software]# mkdir /usr/local/python27   # 创建安装目录

[root@rocket software]# ./configure --prefix=/usr/local/python27

[root@rocket software]# make

[root@rocket software]# make install

# 目前安装的版本是2.6，需要替换成2.7

[root@rocket software]# mv /usr/bin/python /usr/bin/python2.6.6

[root@rocket software]# ln -s /usr/local/python27/bin/python /usr/bin/python

这里需要注意的是，由于原有系统安装的是python2.6，升级了python2.7，那么yum也会出问题

需要修改yum使用python2.6的版本

安装setuptools

进入官网，下载到本地，解压

https://pypi.python.org/pypi/setuptools#downloads

[root@rocket software]# cd setuptools-18.1

[root@rocket setuptools-18.1]# python setup.py install

安装pip

进入官网，下载到本地，解压

https://pypi.python.org/pypi/pip#downloads

[root@rocket software]# cd pip-7.1.2

[root@rocket pip-7.1.2]# python setup.py install

安装Twisted

进入官网，下载到本地，解压

wget https://pypi.python.org/packages/source/T/Twisted/Twisted-15.4.0.tar.bz2

[root@rocket software]# cd Twisted-15.4.0

[root@rocket Twisted-15.4.0]# python setup.py install

安装scrapy

pip install scrapy

在这个过程中，遇到以下问题

1 pip安装模块警告InsecurePlatformWarning: A true SSLContext object is not available.

yum install python-devel libffi-devel openssl-devel

pip install pyopenssl ndg-httpsclient pyasn1

在运行pip就不会出现警告了

2 安装lxml失败

解决方法是先安装libxslt开发包：

yum install libxslt-devel

确认安装成功

[root@rocket software]# rpm -qa | grep libxml

libxml2-devel-2.7.6-20.el6.x86_64

libxml2-python-2.7.6-20.el6.x86_64

libxml2-2.7.6-20.el6.x86_64

3 安装cffi失败

[root@rocket software]# yum -y install libffi-devel

[root@rocket software]# rpm -qa | grep libffi

libffi-3.0.5-3.2.el6.x86_64

libffi-devel-3.0.5-3.2.el6.x86_64

4 安装openssl失败

[root@rocket software]# yum -y install openssl-devel

[root@rocket software]# rpm -qa | grep openssl

openssl-devel-1.0.1e-42.el6.x86_64

openssl-1.0.1e-42.el6.x86_64

解决完以上几个问题后，重新执行

pip install scrapy

能够顺利安装成功。

确认安装成功

[root@rocket Twisted-15.4.0]# python

Python 2.7.6 (default, Oct 27 2015, 01:21:45)

[GCC 4.4.7 20120313 (Red Hat 4.4.7-16)] on linux2

Type "help", "copyright", "credits" or "license" for more information.

>>> import scrapy

没报错，安装成功。

开始第一个scrapy任务

详细介绍请参考

http://scrapy-chs.readthedocs.org/zh_CN/latest/intro/overview.html

[root@rocket scrapy]# scrapy startproject mininova

运行的时候报错，注意运行的时候，必须在mininova的主目录中运行，不然会报错

编写items.py

import scrapy

class MininovaItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    url = scrapy.Field()
    name = scrapy.Field()
    description = scrapy.Field()
    size = scrapy.Field()

编写spiders/mininova_spiders.py

from scrapy.spiders import CrawlSpider, Rule, Spider
from scrapy.linkextractors import LinkExtractor
import scrapy
from mininova.items import MininovaItem

class MininovaSpider(scrapy.spiders.CrawlSpider):
    name = 'mininova'
    allowed_domains = ['mininova.org']
    start_urls = ['http://www.mininova.org/today']
    rules = [Rule(LinkExtractor(allow=['/tor/\d+']), 'parse_torrent')]

    def parse_torrent(self, response):
        torrent = MininovaItem()
        torrent['url'] = response.url
        torrent['name'] = response.xpath("//h1/text()").extract()
        torrent['description'] = response.xpath("//div[@id='description']").extract()
        torrent['size'] = response.xpath("//div[@id='info-left']/p[2]/text()[2]").extract()
        return torrent

运行

[root@rocket mininova]# pwd

/home/demo/scrapy/mininova

[root@rocket mininova]# scrapy crawl mininova -o scraped_data.json

需要安装 sqlite-devel库，再重新编译安装Python

yum install sqlite-devel

[root@rocket software]# yum install sqlite-devel

[root@rocket software]# ./configure --prefix=/usr/local/python27

[root@rocket software]# make

[root@rocket software]# make install

这样就可以找到sqlite3的库了

[root@rocket software]# cd /usr/local/python27/lib/python2.7/lib-dynload/

[root@rocket lib-dynload]# ll|grep sql

-rwxr-xr-x. 1 root root 240971 Oct 28 01:17 _sqlite3.so

[root@rocket mininova]# scrapy crawl mininova -o scraped_data.json

终于可以跑起来了。。

接下来我们将进一步对scrapy的工作原理进行分析，并给出更为实用的例子。