scrapy常用代码段

设置随机请求头

# 安装 pip install fake-useragent
# middleware.py
from fake_useragent import UserAgent
class RandomUserAgentMiddlware(object):
    #随机更换user-agent
    def __init__(self,crawler):
        super(RandomUserAgentMiddlware,self).__init__()
        self.ua = UserAgent()

    @classmethod
    def from_crawler(cls,crawler):
        return cls(crawler)

    def process_request(self,request,spider):
        request.headers.setdefault("User-Agent",self.ua.random)
# ...
# setting.py 中启动RandomUserAgentMiddlware
DOWNLOADER_MIDDLEWARES = {
    'yourProjectName.middlewares.RandomUserAgentMiddlware': 312,
}

设置代理

# 这里使用的是阿布云隧道代理
# middleware.py
import base64

# 代理服务器
proxyServer = "http://http-dyn.abuyun.com:9020"

# 代理隧道验证信息
proxyUser = "your proxyUser"
proxyPass = "your proxyPass"

proxyAuth = "Basic " + base64.urlsafe_b64encode(bytes((proxyUser + ":" + proxyPass), "ascii")).decode("utf8")
class ProxyMiddleware(object):
    def process_request(self, request, spider):
        request.meta["proxy"] = proxyServer
        request.headers["Proxy-Authorization"] = proxyAuth

# ...
# setting.py 中启动RandomUserAgentMiddlware        
DOWNLOADER_MIDDLEWARES = {
     'yourProjectName.middlewares.ProxyMiddleware': 100,
}

图片下载

# pipelines.py
from scrapy import Request
from scrapy.pipelines.images import ImagesPipeline
class ImagePipeline(ImagesPipeline):
    headers = {
		"""如果网站有headers检测就加上"""
    }

    def get_media_requests(self, item, info):
        # 循环每一张图片地址下载，若传过来的不是集合则无需循环直接yield
        for image_url in item['imgurl']:
            headers = self.headers
            headers['Referer'] = item['from_url']
            # meta里面的数据是从spider获取，然后通过meta传递给下面方法：file_path
            yield Request(image_url,headers=headers,meta={'foldername': item['foldername'], 'imgname': item['imgname']})
    # 重命名，若不重写这函数，图片名为哈希
    def file_path(self, request, response=None, info=None):
        pic_format = request.url.split(".")[-1]
        imgname = request.meta['imgname']
        # 接收meta传递过来的图集名称
        foldername = request.meta['foldername']
        # 过滤windows字符串
        foldername = re.sub(r'[？\\*|“<>:/]', '', foldername)
        filename = fr'{foldername}/{imgname}.{pic_format}'
        return filename
   
# ...
# setting.py 中启动ImagePipeline       
DOWNLOADER_MIDDLEWARES = {
     'yourProjectName.pipelines.ImagePipeline': 200,
}

异步写入MySQL

# pipelines.py
from yourProjectName.settings import MYSQL_DBNAME, MYSQL_HOST,MYSQL_PASSWORD,MYSQL_PORT,MYSQL_USER


class MysqlTwistedPipeline(object):
    """
    异步写入mysql
    """
    def __init__(self, dbpool):
        self.dbpool = dbpool

    @classmethod
    def from_settings(cls,setting):
        dbparms = dict(
            host=MYSQL_HOST,
            db=MYSQL_DBNAME,
            user=MYSQL_USER,
            passwd=MYSQL_PASSWORD,
            port=MYSQL_PORT,
            charset='utf8',
            cursorclass=pymysql.cursors.DictCursor,
            use_unicode=False,
        )
        dbpool = adbapi.ConnectionPool("pymysql", **dbparms)
        return cls(dbpool)

    def process_item(self, item, spider):
        query = self.dbpool.runInteraction(self.do_insert, item)
        query.addCallback(self.handle_error)

    def handle_error(self, failure):
        print("MysqlTwistedPipeline error is :",failure)

    def do_insert(self, cursor, item):
        insert_sql = """insert_sql"""
        cursor.execute(insert_sql, ())#有些情况需使用pymysql.escape_string()对item字段进行转义

# ...
# setting.py 中启动ImagePipeline       
DOWNLOADER_MIDDLEWARES = {
     'yourProjectName.pipelines.MysqlTwistedPipeline': 200,
}