标签：lin meta 返回 init 选择器 wan user 5.4 setting
创建scrapy项目:
scrapy startproject 项目名
cd到项目名下
scrapy genspider 爬虫名 www.baidu.com(网站网址)
之后按照提示创建爬虫文件（官方测试网站为http://quotes.toscrape.com/）
创建启动文件
from scrapy.cmdline import execute
execute([‘scrapy‘,‘crawl‘,‘quotes‘])
quotes是爬虫名，该文件创建在scrapy项目根目录下
css选择器:
response.css(‘.text::text‘).extract()
这里为提取所有带有class=’text’ 这个属性的元素里面的text返回的是一个列表
response.css(‘.text::text‘).extract_first()
这是取第一条，返回的是str
print(response.css("div span::attr(class)").extract())
这是取元素
Xpath选择器:
url = response.url+response.xpath(‘/html/body/div/div[2]/div[1]/div[1]/div/a[1]/@href‘).extract_first()
和原来用法基本一样，这里是获取一个url 然后跟网站的主url拼接了
print(response.xpath("//a[@class=‘tag‘]/text()").extract())
取带有class=’tag’属性的超链接中间的文本内容
print(response.url)
print(response.status)
打印该请求的url,打印请求的状态码
保存为json形式的东西
scrapy crawl quotes -o quotes.json
json lines存储
scrapy crawl quotes -o quotes.jl
scrapy crawl quotes -o quotes.csv
scrapy crawl quotes -o quotes.xml
scrapy crawl quotes -o quotes.pickle
scrapy crawl quotes -o quotes.marshal
scrapy crawl quotes -o ftp://user:pass@ftp.example.com/path/to/quotes.csv
piplines.py中的操作
from scrapy.exceptions import DropItem
class HelloPipeline(object):
def __init__(self):
self.limit = 50
def process_item(self,item,spider):
if item[‘name‘]:
if len(item[‘name‘]) > self.limit:
item[‘name‘] = item[‘name‘][:self.limit].rstrip()+‘。。。‘
return item
else:
return DropItem
import pymongo
class MongoPipline(object):
def __init__(self,mongo_url,mongo_db):
self.mongo_url = mongo_url
self.mongo_db = mongo_db
@classmethod
def from_crawler(cls,crawler):
return cls(mongo_url=crawler.settings.get(‘MONGO_URI‘),mongo_db=crawler.settings.get(‘MONGO_DB‘))
def open_spider(self,spider):
print(self.mongo_url,self.mongo_db)
self.client = pymongo.MongoClient(self.mongo_url)
self.db = self.client[self.mongo_db]
def process_item(self,item,spider):
self.db[‘name‘].insert(dict(item))
print(item)
return item
def close_spider(self,spider):
self.client.close()
记得开setting.py：
ITEM_PIPELINES = {
‘hello.pipelines.HelloPipeline‘: 300,
‘hello.pipelines.MongoPipline‘: 400,
}
MONGO_URI = ‘127.0.0.1‘
MONGO_DB = ‘hello‘
DownloadMiddleware
核心方法:
Process_request(self,request,spider)
Return None：继续处理这个request，直到返回response,通常用来修改request
Return Response 直接返回该response
Return Request 将返回的request 重新放归调度队列，当成一个新的request用
Return IgnoreRequest 抛出异常，process_exception被一次调用，
Process_response(self,request,response,spider)
Return request将返回的request 重新放归调度队列，当成一个新的request用
Return response 继续处理该response直到结束
Process_exception(request,excetion,spider)
Return IgnoreRequest 抛出异常，process_exception被一次调用，
通过重写中间件给request加useragent,将返回的状态码都改成201
在setting里:
DOWNLOADER_MIDDLEWARES = {
‘dingdian.middlewares.AgantMiddleware‘: 543,
}
在middleware里:
import random
class AgantMiddleware(object):
def __init__(self):
self.user_agent
= [‘Mozilla/5.0 (Windows NT 10.0; WOW64;
rv:58.0) Gecko/20100101 Firefox/58.0‘]
def process_request(self,request,spider):
request.headers[‘User-Agent‘] = random.choice(self.user_agent)
print(request.headers)
def process_response(self,request,response,spider):
response.status=201
return response
scrapy两种请求方式
一种
import scrapy
yield scrapy.Request(begin_url,self.first)
第二种
from scrapy.http import Request
yield Request(url,self.first,meta={‘thename‘:pic_name[0]})
使用post请求的方法:
from scrapy import FormRequest ##Scrapy中用作登录使用的一个包
formdata = {
‘username‘: ‘wangshang‘,
‘password‘: ‘a706486‘
}
yield scrapy.FormRequest(
url=‘http://172.16.10.119:8080/bwie/login.do‘,
formdata=formdata,
callback=self.after_login,
)
中间键添加代理IP以及header头
class UserAgentMiddleware(object):
def __init__(self):
self.user_agent
= [‘Mozilla/5.0 (Windows NT 10.0; Win64; x64)
AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.117 Safari/537.36‘,‘Mozilla/5.0
(Windows NT 10.0; WOW64; rv:58.0) Gecko/20100101 Firefox/58.0‘]
def process_request(self,request,spider):
request.meta[‘proxy‘] = ‘http://‘+‘175.42.123.111:33995‘
标签：lin meta 返回 init 选择器 wan user 5.4 setting
原文地址：https://www.cnblogs.com/6-b-timer-shaft/p/10632974.html
