# Request 部分源碼：
class Request(object_ref):

    def __init__(self, url, callback=None, method='GET', headers=None, body=None, 
                 cookies=None, meta=None, encoding='utf-8', priority=0,
                 dont_filter=False, errback=None):

        self._encoding = encoding  # this one has to be set first
        self.method = str(method).upper()
        self._set_url(url)
        self._set_body(body)
        assert isinstance(priority, int), "Request priority not an integer: %r" % priority
        self.priority = priority

        assert callback or not errback, "Cannot use errback without a callback"
        self.callback = callback
        self.errback = errback

        self.cookies = cookies or {}
        self.headers = Headers(headers or {}, encoding=encoding)
        self.dont_filter = dont_filter

        self._meta = dict(meta) if meta else None

    @property
    def meta(self):
        if self._meta is None:
            self._meta = {}
        return self._meta




'''
    url: 就是需要請(qǐng)求仪缸，并進(jìn)行下一步處理的url

    callback: 指定該請(qǐng)求返回的Response饮寞，由那個(gè)函數(shù)來(lái)處理翘瓮。

    method: 請(qǐng)求一般不需要指定，默認(rèn)GET方法，可設(shè)置為"GET", "POST", "PUT"等，且保證字符串大寫

    headers: 請(qǐng)求頭

    cookies: cookies,模擬用戶登錄需要指定用戶的cookies,字典dict型

    meta: 比較常用，在不同的請(qǐng)求之間傳遞數(shù)據(jù)使用的弛饭。字典dict型
'''

      request_with_cookies = Request(
          url="http://www.example.com",
          cookies={'currency': 'USD', 'country': 'UY'},
          meta={'dont_merge_cookies': True}
      )
'''
    encoding: 編碼類型,使用默認(rèn)的 'utf-8' 就行。

    dont_filter: 表明該請(qǐng)求不由調(diào)度器過(guò)濾伏恐。這是當(dāng)你想使用多次執(zhí)行相同的請(qǐng)求,忽略重復(fù)的過(guò)濾器孩哑。默認(rèn)為False。

    errback: 指定錯(cuò)誤處理函數(shù)
'''



# 如果希望程序執(zhí)行一開(kāi)始就發(fā)送POST請(qǐng)求翠桦，可以重寫Spider類的start_requests(self) 方法横蜒，并且不再調(diào)用start_urls里的url胳蛮。

class mySpider(scrapy.Spider):

    name = 'myspider'
    allow_domeas = ['renren.com']
    start_urls = ["http://www.renren.com/PLogin.do"]

    def start_requests(self):
        # FormRequest 是Scrapy發(fā)送POST請(qǐng)求的方法
        for url in self.start_urls:

            yield scrapy.FormRequest(
                url = url,
                formdata = {"email" : "mr_mao_hacker@163.com", "password" : "axxxxxxxe"},
                callback = self.parse_page
            )

    def parse_page(self, response):
        """
        請(qǐng)求成的回調(diào)函數(shù)
        """
        pass

Response
class Response(object_ref):
    def __init__(self, url, status=200, headers=None, body='', flags=None, request=None):
        self.headers = Headers(headers or {})
        self.status = int(status)
        self._set_body(body)
        self._set_url(url)
        self.request = request
        self.flags = [] if flags is None else list(flags)

    @property
    def meta(self):
        try:
            return self.request.meta
        except AttributeError:
            raise AttributeError("Response.meta not available, this response " \
                "is not tied to any request")

'''
    status: 響應(yīng)碼
    body： 響應(yīng)體
    url：響應(yīng)url
    self.request (request對(duì)象)
    self.headers　(響應(yīng)頭)
'''