import requests

from lxml import etree

import json

class BtcSpider(object):

    def __init__(self):

        self.headers = {

            "User-Agent": 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36'

        }

        self.base_url = "https://www.chainnode.com/forum/2"

        self.data_list = []

    # 获取数据

    def get_data(self, url):

        response = requests.get(url, headers=self.headers)

        data = response.content.decode()

        return data

    #  解析数据

    def parse_data(self, data):

        # 转换数据的类型

        x_data = etree.HTML(data)

        # 按照路径解析

        title_list = x_data.xpath('//a[@class="link-dark-major font-bold bbt-block"]/text()')

        url_list = x_data.xpath('//a[@class="link-dark-major font-bold bbt-block"]/@href')

        url_list = ["https://www.chainnode.com" + i for i in url_list]

        for index, title in enumerate(title_list):

            news = {}

            news['name'] = title

            news['url'] = url_list[index]

            self.data_list.append(news)

    # 保存数据

    def save_data(self):

        data_str = json.dumps(self.data_list)

        with open('03-btc.html', 'w') as f:

            f.write(data_str)

    # 启动

    def run(self):

        for i in range(1,5):

            # 拼接完整url

            url = self.base_url if i == 1 else self.base_url + str(-i)

            # 发送请求

            data = self.get_data(url)

            # 解析数据

            self.parse_data(data)

        self.save_data()

BtcSpider().run()