scrapy入门实战-爬取代理网站

入门scrapy。

学习了有这几点

1.如何使用scrapy框架对网站进行爬虫；

2.如何对网页源代码使用xpath进行解析；

3.如何书写spider爬虫文件，对源代码进行解析；

4.学会使用scrapy的基础命令，创建项目，使用模板生成一个爬虫文件spider；

5,通过配置settings.py反爬虫。如设置user-agent；

设定目标:爬取网络代理www.xicidaili.com网站。

使用scrapy startproject 项目名称

scrapy startproject xicidailiSpider

项目名称应该如何命名呢：建议是需要爬虫的域名+Spider.举个例子：比如要爬取www.zhihu.com,那么项目名称可以写成zhihuSpider。

会在目录中出现该文件目录：

2.  目录中spiders放置的是爬虫文件，然后middlewares.py是中间件，有下载器的中间件，有爬虫文件的中间件。pipelines.py是管道文件，是对spider爬虫文件解析数据的处理。settings.py是设置相关属性，是否遵守爬虫的robotstxt协议，设置User-Agent等。

3.可以使用scrapy提供的模板，命令如下：

scrapy genspider 爬虫名字   需要爬虫的网络域名

举例子：

我们需要爬取的www.xicidaili.com

那么可以使用

scarpy genspider xicidaili  xicidaili.com

命令完成后，最终的目录如下：

建立后项目后，需要对提取的网页进行分析

经常使用的有三种解析模式：

1.正则表达式

2 xpath   response.xpath("表达式")

3 css    response.css("表达式")

XPath的语法是w3c的教程。http://www.w3school.com.cn/xpath/xpath_syntax.asp

需要安装一个xpath helper插件在浏览器中，可以帮助验证书写的xpath是否正确。

xpath语法需要多实践，看确实不容易记住。

xicidaili.py

　　

# -*- coding: utf-8 -*-
import scrapy

# 继承scrapy,Spider类
class XicidailiSpider(scrapy.Spider):
    name = 'xicidaili'
    allowed_domains = ['xicidaili.com']
    start_urls = ['https://www.xicidaili.com/nn/',
                  "https://www.xicidaili.com/nt/",
                  "https://www.xicidaili.com/wn/,"
                  "https://www.xicidaili.com/wt/"]

    # 解析响应数据，提取数据和网址等。
    def parse(self, response):
        selectors = response.xpath('//tr')
        for selector in selectors:
            ip = selector.xpath("./td[2]/text()").get()
            port = selector.xpath("./td[3]/text()").get()     #.代表当前节点下
            country = selector.xpath("./td[4]/a/text()").get()   # get()和extract_first() 功能相同，getall()获取多个
            # print(ip,port,country)
            Items={
                "ip":ip,
                "port":port,
                "country":country
            }
            yield  Items
        """
        # 翻页操作
        # 获取下一页的标签
        next_page = response.xpath("//a[@class='next_page']/@href").get()
        # 判断next_page是否有值，也就是是否到了最后一页
        if next_page:
            # 拼接网页url---response.urljoin
            next_url = response.urljoin(next_page)
            # 判断最后一页是否
            yield  scrapy.Request(next_url,callback=self.parse)   # 回调函数不要加括号
    """

# -*- coding: utf-8 -*-
# settings.py设置
# Scrapy settings for xicidailiSpider project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     https://doc.scrapy.org/en/latest/topics/settings.html
#     https://doc.scrapy.org/en/latest/topics/downloader-middleware.html
#     https://doc.scrapy.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'xicidailiSpider'

SPIDER_MODULES = ['xicidailiSpider.spiders']
NEWSPIDER_MODULE = 'xicidailiSpider.spiders'

# 设置到处文件的字符编码
FEED_EXPORT_ENCODING ="UTF8"
# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'xicidailiSpider (+http://www.yourdomain.com)'

# Obey robots.txt rules
# 是否准售robots.txt协议，不遵守
ROBOTSTXT_OBEY = False

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See https://doc.scrapy.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False

# Override the default request headers:
DEFAULT_REQUEST_HEADERS = {
   'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
   'Accept-Language': 'en',
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) \
    AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36'
}

# Enable or disable spider middlewares
# See https://doc.scrapy.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'xicidailiSpider.middlewares.XicidailispiderSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See https://doc.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'xicidailiSpider.middlewares.XicidailispiderDownloaderMiddleware': 543,
#}

# Enable or disable extensions
# See https://doc.scrapy.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
#}

# Configure item pipelines
# See https://doc.scrapy.org/en/latest/topics/item-pipeline.html
#ITEM_PIPELINES = {
#    'xicidailiSpider.pipelines.XicidailispiderPipeline': 300,
#}

# Enable and configure the AutoThrottle extension (disabled by default)
# See https://doc.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True
# The initial download delay
#AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False

# Enable and configure HTTP caching (disabled by default)
# See https://doc.scrapy.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
#HTTPCACHE_ENABLED = True
#HTTPCACHE_EXPIRATION_SECS = 0
#HTTPCACHE_DIR = 'httpcache'
#HTTPCACHE_IGNORE_HTTP_CODES = []
#HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

　运行

scrapy crawl xicidai 项目名，这个必须唯一。

如果需要输出文件，

scarpy crawl xicidaili --output ip.json 或者ip.csv