url_manager.py

"""
URL管理器
"""


class UrlManager(object):
    def __init__(self):
        self.new_urls = set()  # 待爬取的url集合
        self.old_urls = set()  # 已爬取的url集合

    def add_new_url(self, url):
        """
        添加新的带爬取的url
        :param url:
        :return:
        """
        if url is None:
            return
        if url not in self.new_urls and url not in self.old_urls:
            # 若为新的Url，则添加进待爬取的url集合中
            self.new_urls.add(url)

    def add_new_urls(self, urls):
        """
        批量添加新的带爬取的url集合
        :param urls:
        :return:
        """
        if urls is None or len(urls) == 0:
            return
        for url in urls:
            self.add_new_url(url)

    def has_new_url(self):
        """
        检测待爬取集合是否为空
        :return:
        """
        return len(self.new_urls) != 0

    def get_new_url(self):
        """
        获取要爬取的url
        :return:
        """
        new_url = self.new_urls.pop()  # 获取url并从集合中剔除该url
        self.old_urls.add(new_url)  # 将获取的url添加进已爬取的url中
        return new_url