python之scrapy的debug、shell、settings、pipelines

1、debug了解

2、scrapy shell了解

Scrapy shell是一个交互终端，我们可以在未启动spider的情况下尝试及调试代码，也可以用来测试XPath表达式

使用方法：
    scrapy shell https://gosuncn.zhiye.com/social/


response.url：当前响应的url地址
response.request.url：当前响应对应的请求的url地址
response.headers：响应头
response.body：响应体，也就是html代码，默认是byte类型
response.requests.headers：当前响应的请求头

 3、settings.py

# -*- coding: utf-8 -*-

# Scrapy settings for gosuncn 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
#settings文件一般存取全局变量，如数据库的账号，密码等###
BOT_NAME = 'gosuncn'

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

LOG_LEVEL="WARNING"
# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'gosuncn (+http://www.yourdomain.com)'

# Obey robots.txt rules
#遵守ROBOT协议，也就是会先请求ROBOT协议
ROBOTSTXT_OBEY = True

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#并发数
#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
#下载延迟，每次请求前，先睡3秒
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
#和DOWNLOAD_DELAY配合使用
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
#设置COOKIES，默认携带COOKIES信息
#COOKIES_ENABLED = False

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

# Override the default request headers:
#默认请求头
#DEFAULT_REQUEST_HEADERS = {
#   'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
#   'Accept-Language': 'en',
#}

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

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

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

#配置pipelines，数字为权重值，越小越先执行
# Configure item pipelines
# See https://doc.scrapy.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
   'gosuncn.pipelines.GosuncnPipeline': 300,
}
LOG_LEVEL ="WARNING"
LOG_FILE = "./log.log"

#对爬虫进行限速
# 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

#HTTP缓存
# 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'

4、pipelines的open_spider和close_spider函数

# -*- coding: utf-8 -*-

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: https://doc.scrapy.org/en/latest/topics/item-pipeline.html
import  re
from gosuncn.items import GosuncnItem
class GosuncnPipeline(object):

    def open_spider(self,spider):
        """
        爬虫启动时执行，启动数据库连接
        :param spider:
        :return:
        """
        spider.hello = "open"

    def process_item(self, item, spider):
        if isinstance(item,GosuncnItem):
            item["content"] = self.process_content(item["content"])
            print(item)
        return item

    def process_content(self,content):
        content =[re.sub(r"
|' '","",i) for i in content]
        content = [i for i in content if len(i)>0]
        return content

    def close_spider(self,spider):
        """
        爬虫结束时执行，关闭数据库连接
        :param spider:
        :return:
        """
        spider.hello = "close"
# class GosuncnPipeline1(object):
#     def process_item(self, item, spider):
#         if isinstance(item,GosuncnItem):
#             print(item)
#         return item