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python增量爬虫pyspider
1.为了能够将爬取到的数据存入本地数据库，现在本地创建一个MySQL数据库example，然后
在数据库中建立一张表格test，示例如下：
DROP TABLE IF EXISTS `test`;
CREATE TABLE `douban_db` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`url` varchar(20) NOT NULL,
`direct` varchar(30),
`performer` date,
`type` varchar(30),
`district` varchar(20) NOT NULL,
`language` varchar(30),
`date` varchar(30),
`time` varchar(30),
`alias` varchar(20) NOT NULL,
`score` varchar(30),
`comments` varchar(300),
`scenario` varchar(300),
`IMDb` varchar(30),
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
2.如果使用开源框架pyspider来进行爬虫的话，默认情况下，会把爬取到的结果存放到result.db这个sqilite数据库中，但是为了方便操作，我们将结果存放到mysql中。接下
来要做的一个操作就是重写on_result方法，实例化调用我们自己实现的SQL方法，具体
实例如下：
#!/usr/bin/env python
# -*- encoding: utf-8 -*-
# Created on 2015-03-20 09:46:20
# Project: fly_spider
import re
from pyspider.database.mysql.mysqldb import SQL
from pyspider.libs.base_handler import *
class Handler(BaseHandler):
headers= {
"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"Accept-Encoding":"gzip, deflate, sdch",
"Accept-Language":"zh-CN,zh;q=0.8",
"Cache-Control":"max-age=0",
"Connection":"keep-alive",
"User-Agent":"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.101 Safari/537.36"
}
crawl_config = {
"headers" : headers,
"timeout" : 100
}
@every(minutes=24 * 60)
def on_start(self):
self.crawl(‘http://movie.douban.com/tag/‘, callback=self.index_page)
@config(age=10 * 24 * 60 * 60)
def index_page(self, response):
for each in response.doc(‘a[href^="http"]‘).items():
if re.match("http://movie.douban.com/tag/\w+", each.attr.href, re.U):
self.crawl(each.attr.href, callback=self.list_page)
@config(age=10*24*60*60, priority=2)
def list_page(self, response):
for each in response.doc(‘html > body > div#wrapper > div#content > div.grid-16-8.clearfix > div.article > div > table tr.item > td > div.pl2 > a‘).items():
self.crawl(each.attr.href, priority=9, callback=self.detail_page)
@config(priority=3)
def detail_page(self, response):
return {
"url": response.url,
"title": response.doc(‘html > body > #wrapper > #content > h1 > span‘).text(),
"direct": ",".join(x.text() for x in response.doc(‘a[rel="v:directedBy"]‘).items()),
"performer": ",".join(x.text() for x in response.doc(‘a[rel="v:starring"]‘).items()),
"type": ",".join(x.text() for x in response.doc(‘span[property="v:genre"]‘).items()),
# "district": "".join(x.text() for x in response.doc(‘a[rel="v:starring"]‘).items()),
# "language": "".join(x.text() for x in response.doc(‘a[rel="v:starring"]‘).items()),
"date": ",".join(x.text() for x in response.doc(‘span[property="v:initialReleaseDate"]‘).items()),
"time": ",".join(x.text() for x in response.doc(‘span[property="v:runtime"]‘).items()),
# "alias": "".join(x.text() for x in response.doc(‘a[rel="v:starring"]‘).items()),
"score": response.doc(‘.rating_num‘).text(),
"comments": response.doc(‘html > body > div#wrapper > div#content > div.grid-16-8.clearfix > div.article > div#comments-section > div.mod-hd > h2 > i‘).text(),
"scenario": response.doc(‘html > body > div#wrapper > div#content > div.grid-16-8.clearfix > div.article > div.related-info > div#link-report.indent‘).text(),
"IMDb": "".join(x.text() for x in response.doc(‘span[href]‘).items()),
}
def on_result(self, result):
if not result or not result[‘title‘]:
return
sql = SQL()
sql.replace(‘douban_db‘,**result)
关于上面这段代码，有下面几点需要说明的：
a. 为了避免服务器判断出客户端在进行爬虫操作，从而禁止ip访问（具体表现为出现403禁止访问），我们需要在发出请求的时候加上一个http头，伪装成使用浏览器访问，具体用法如下：
headers= {
"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"Accept-Encoding":"gzip, deflate, sdch",
"Accept-Language":"zh-CN,zh;q=0.8",
"Cache-Control":"max-age=0",
"Connection":"keep-alive",
"User-Agent":"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.101 Safari/537.36"
}
crawl_config = {
"headers" : headers,
"timeout" : 100
}
b. @every(minutes=24 * 60)表示每天执行一次
@config(age=10 * 24 * 60 * 60)表示数据10天后就过期了
c. 接下来是一个比较重要的地方，重写on_result方法，相当于实现了一个多态，程序在最后返回时，会执行on_result方法，默认的情况下，on_result是将数据刷入sqlite中，但是如果我们需要将数据插入mysql中，就需要重写on_result方法，具体使用如下：
def on_result(self, result):
if not result or not result[‘title‘]:
return
sql = SQL()
sql.replace(‘test‘,**result) 注意这里的if not result or not result[‘title’]:这句判断很重要，不然的会会报错，提示result是未定义类型的。
3.在上面的额代码中，提到了实例化调用我们自己实现的SQL方法，并且引用了from pyspider.database.mysql.mysqldb import SQL这个库文件，那么就必须在这个目录下实现这个库，具体如下：
把下面内容文文放到pyspider/pyspider/database/mysql/目录下命名为mysqldb.py
from six import itervalues
import mysql.connector
from datetime import date, datetime, timedelta
class SQL:
username = ‘root‘ #数据库用户名
password = ‘root‘ #数据库密码
database = ‘test‘ #数据库
host = ‘172.30.25.231‘ #数据库主机地址
connection = ‘‘
connect = True
placeholder = ‘%s‘
def __init__(self):
if self.connect:
SQL.connect(self)
def escape(self,string):
return ‘`%s`‘ % string
def connect(self):
config = {
‘user‘:SQL.username,
‘password‘:SQL.password,
‘host‘:SQL.host
}
if SQL.database != None:
config[‘database‘] = SQL.database
try:
cnx = mysql.connector.connect(**config)
SQL.connection = cnx
return True
except mysql.connector.Error as err:
if (err.errno == errorcode.ER_ACCESS_DENIED_ERROR):
print "The credentials you provided are not correct."
elif (err.errno == errorcode.ER_BAD_DB_ERROR):
print "The database you provided does not exist."
else:
print "Something went wrong: " , err
return False
def replace(self,tablename=None,**values):
if SQL.connection == ‘‘:
print "Please connect first"
return False
tablename = self.escape(tablename )
if values:
_keys = ", ".join(self.escape(k) for k in values)
_values = ", ".join([self.placeholder, ] * len(values))
sql_query = "REPLACE INTO %s (%s) VALUES (%s)" % (tablename, _keys, _values)
else:
sql_query = "REPLACE INTO %s DEFAULT VALUES" % tablename
cur = SQL.connection.cursor()
try:
if values:
cur.execute(sql_query, list(itervalues(values)))
else:
cur.execute(sql_query)
SQL.connection.commit()
return True
except mysql.connector.Error as err:
print ("An error occured: {}".format(err))
return False
学习文档：http://blog.binux.me/2015/01/pyspider-tutorial-level-1-html-and-css-selector/
测试环境：http://demo.pyspider.org/
python增量爬虫pyspider
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