Scrapy中如何向Spider传入参数
作者:互联网
目录
方式一
方式二
settings.py
run.py
pipelines.py
启动示例
在使用Scrapy爬取数据时,有时会碰到需要根据传递给Spider的参数来决定爬取哪些Url或者爬取哪些页的情况。
例如,百度贴吧的放置奇兵吧的地址如下,其中 kw参数用来指定贴吧名称、pn参数用来对帖子进行翻页。
https://tieba.baidu.com/f?kw=放置奇兵&ie=utf-8&pn=250
如果我们希望通过参数传递的方式将贴吧名称和页数等参数传给Spider,来控制我们要爬取哪一个贴吧、爬取哪些页。遇到这种情况,有以下两种方法向Spider传递参数。
方式一
通过 scrapy crawl 命令的 -a 参数向 spider 传递参数。
# -*- coding: utf-8 -*-
import scrapy
class TiebaSpider(scrapy.Spider):
name = 'tieba' # 贴吧爬虫
allowed_domains = ['tieba.baidu.com'] # 允许爬取的范围
start_urls = [] # 爬虫起始地址
# 命令格式: scrapy crawl tieba -a tiebaName=放置奇兵 -a pn=250
def __init__(self, tiebaName=None, pn=None, *args, **kwargs):
print('< 贴吧名称 >: ' + tiebaName)
super(eval(self.__class__.__name__), self).__init__(*args, **kwargs)
self.start_urls = ['https://tieba.baidu.com/f?kw=%s&ie=utf-8&pn=%s' % (tiebaName,pn)]
def parse(self, response):
print(response.request.url) # 结果:https://tieba.baidu.com/f?kw=%E6%94%BE%E7%BD%AE%E5%A5%87%E5%85%B5&ie=utf-8&pn=250
方式二
仿照 scrapy 的 crawl 命令的源代码,重新自定义一个专用命令。
settings.py
首先,需要在settings.py文件中增加如下配置来指定自定义 scrapy 命令的存放目录。
# 指定 Scrapy 命令存放目录
COMMANDS_MODULE = 'baidu_tieba.commands'
run.py
在指定的命令存放目录中创建命令文件,在这里我们创建的命令文件为 run.py ,将来执行的命令格式为:
scrapy run [ -option option_value] 。
import scrapy.commands.crawl as crawl
from scrapy.exceptions import UsageError
from scrapy.commands import ScrapyCommand
class Command(crawl.Command):
def add_options(self, parser):
# 为命令添加选项
ScrapyCommand.add_options(self, parser)
parser.add_option("-k", "--keyword", type="str", dest="keyword", default="",
help="set the tieba's name you want to crawl")
parser.add_option("-p", "--pageNum", type="int", action="store", dest="pageNum", default=0,
help="set the page number you want to crawl")
def process_options(self, args, opts):
# 处理从命令行中传入的选项参数
ScrapyCommand.process_options(self, args, opts)
if opts.keyword:
tiebaName = opts.keyword.strip()
if tiebaName != '':
self.settings.set('TIEBA_NAME', tiebaName, priority='cmdline')
else:
raise UsageError("U must specify the tieba's name to crawl,use -kw TIEBA_NAME!")
self.settings.set('PAGE_NUM', opts.pageNum, priority='cmdline')
def run(self, args, opts):
# 启动爬虫
self.crawler_process.crawl('tieba')
self.crawler_process.start()
pipelines.py
在BaiduTiebaPipeline的open_spider()方法中利用 run 命令传入的参数对TiebaSpider进行初始化,在这里示例设置了一下start_urls。
# -*- coding: utf-8 -*-
import json
class BaiduTiebaPipeline(object):
@classmethod
def from_settings(cls, settings):
return cls(settings)
def __init__(self, settings):
self.settings = settings
def open_spider(self, spider):
# 开启爬虫
spider.start_urls = [
'https://tieba.baidu.com/f?kw=%s&ie=utf-8&pn=%s' % (self.settings['TIEBA_NAME'], self.settings['PAGE_NUM'])]
def close_spider(self, spider):
# 关闭爬虫
pass
def process_item(self, item, spider):
# 将帖子内容保存到文件
with open('tieba.txt', 'a', encoding='utf-8') as f:
json.dump(dict(item), f, ensure_ascii=False, indent=2)
return item
设置完成后,别忘了在settings.py中启用BaiduTiebaPipeline。
ITEM_PIPELINES = {
'baidu_tieba.pipelines.BaiduTiebaPipeline': 50,
}
启动示例
大功告成,参照如下命令格式启动贴吧爬虫。
scrapy run -k 放置奇兵 -p 250
参考文章:
https://blog.csdn.net/c0411034/article/details/81750028
https://blog.csdn.net/qq_24760381/article/details/80361400
https://blog.csdn.net/qq_38282706/article/details/80991196
标签:tieba,settings,self,传入,Spider,Scrapy,crawl,def,scrapy 来源: https://blog.csdn.net/u011250186/article/details/103962056