下载中间件

class DownMiddleware1(object):
    def process_request(self, request, spider):
        """
        请求需要被下载时，经过所有下载器中间件的process_request调用
        :param request: 
        :param spider: 
        :return:  
            None,继续后续中间件去下载；
            Response对象，停止process_request的执行，开始执行process_response
            Request对象，停止中间件的执行，将Request重新调度器
            raise IgnoreRequest异常，停止process_request的执行，开始执行process_exception
        """

"""
from scrapy.http import Request
# print(request)
# request.method = "POST"
request.headers['proxy'] = ' {'ip_port': '111.11.228.75:80', 'user_pass': ''},'
return None
"""


"""
from scrapy.http import Response
import requests
v = request.get('http://www.baidu.com')
data = Response(url='xxxxxx',body=v.content,request=request)
return data

"""

       


    def process_response(self, request, response, spider):
        """
        spider处理完成，返回时调用
        :param response:
        :param result:
        :param spider:
        :return: 
            Response 对象：转交给其他中间件process_response
            Request 对象：停止中间件，request会被重新调度下载
            raise IgnoreRequest 异常：调用Request.errback
        """
        print('response1')
        return response

    def process_exception(self, request, exception, spider):
        """
        当下载处理器(download handler)或 process_request() (下载中间件)抛出异常
        :param response:
        :param exception:
        :param spider:
        :return: 
            None：继续交给后续中间件处理异常；
            Response对象：停止后续process_exception方法
            Request对象：停止中间件，request将会被重新调用下载
        """
        return None

##settings设置

DOWNLOADER_MIDDLEWARES = {
   # 'sp3.middlewares.Sp3DownloaderMiddleware': 543,
    'sp3.middlewares.DownMiddleware1':541,
}