Scrapy框架初探( 二 ) _Scrapy框架

meta The initial values for the Request.meta attribute. If given, the dict passed in this parameter will be shallow copied.该参数也是字典形式，是为了在spider类的多个parse函数之间传递信息，见知乎。注意Response对象也有一个它对应的Request对象：The Request object that generated this response. This attribute is assigned in the Scrapy engine, after the response and the request have passed through all Downloader Middlewares In particular, this means that:HTTP redirections will cause the original request (to the URL before redirection) to be assigned to the redirected response (with the final URL after redirection).Response.request.url doesn’t always equal Response.urlThis attribute is only available in the spider code, and in the Spider Middlewares, but not in Downloader Middlewares (although you have the Request available there by other means) and handlers of the response_downloaded signal.But Unlike the Response.request attribute, the Response.meta attribute is propagated along redirects and retries, so you will get the original Request.meta sent from your spider.

Response obejct这里仅介绍一些reponse对象的属性：

url 即该response的来源url
status 即该response的状态码
headers response的响应头，形式为dict
body response的相应数据体，形式为bytes
request response对应的Request对象，对于它上文已经介绍，即Response.url可能不等于Reponse.request.url ，因为redirection的原因

SettingsSettings can be populated using different mechanisms, each of which having a different precedence. Here is the list of them in decreasing order of precedence: