python爬虫 1.自己定义类实现scrapy框架的基本功能

1.定义调度器，引擎，下载器，爬虫器，管道器

# 调度器，下载器，爬虫器，引擎，管道类
 
class Scheduler():
    """调度器类"""
    def __init__(self):
        pass
 
class Downloader():
    """下载器类"""
    def __init__(self):
        pass
 
class Spider():
    """爬虫器类"""
    def __init__(self):
        pass
 
class Engine():
    """引擎类"""
    def __init__(self):
        pass
 
    def run(self):
        pass
 
class Pipline():
    """管道类"""
    def open_spider(self,spider):
        pass
 
    def process_item(self,item,spider):
        return item
 
    def close_spider(self,spider):
        pass