好久没写爬虫了，有些生疏了，虽然之前也只是会简单的爬，先记录一下。用的是Scrapy框架。
首先 scrapy startproject jianshu
第一步，编容器 items.py

import scrapy

class JianshuItem(scrapy.Item):

    title = scrapy.Field()
    author = scrapy.Field()
    post_time = scrapy.Field()
    read = scrapy.Field()
    comment = scrapy.Field()
    like = scrapy.Field()
    reward = scrapy.Field()
    subject = scrapy.Field()

第二步，程序的核心 jianshu_spider.py

from scrapy.spiders import Spider
from scrapy.selector import Selector

from ..items import JianshuItem


class JianshuSpider(Spider):
    name = "jianshu_spider"

    allowed_domains = []

    start_urls = ['http://www.jianshu.com/']

    def parse(self, response):
        sel = Selector(response)

        title = sel.xpath("//div[@class='content']/a[@class='title']/text()").extract()
        author = sel.xpath("//div[@class='author']/div[@class='name']/a/text()").extract()
        post_time = sel.xpath("//div[@class='content']/div[@class='name']/span[@class='time']/@data-shared-at").extract()
        read = sel.xpath("//div[@class='content']/div[@class='meta']/a[2]/text()").extract()
        comment = sel.xpath("//div[@class='content']/div[@class='meta']/a[3]/text()").extract()
        like = sel.xpath("//div[@class='content']/div[@class='meta']/span[1]/text()").extract()
        reward = sel.xpath("//div[@class='content']/div[@class='meta']/span[2]/text()").extract()
        subject = sel.xpath("//div[@class='content']/div[@class='meta']/a[@class='collection-tag']/text()").extract()

        item = JianshuItem()

        item['title'] = [i for i in title]
        item['author'] = [i for i in author]
        item['post_time'] = [i for i in post_time]
        item['read'] = [i for i in read]
        item['comment'] = [i for i in comment]
        item['like'] = [i for i in like]
        item['reward'] = [i for i in reward]
        item['subject'] = [i for i in subject]

        yield item

第三步，交给pipelines.py处理

import json
import codecs


class JianshuPipeline(object):

    def __init__(self):
        self.file = codecs.open('jianshu.json', mode='wb', encoding='utf-8')

    def process_item(self, item, spider):
        line = 'List:' + '\n'

        for i in range(len(item['title'])):
            title = {'title': item['title'][i]}
            author = {'author': item['author'][i]}
            post_time = {'post_time': item['post_time'][i]}
            read = {'read': item['read'][i]}
            comment = {'comment': item['comment'][i]}
            like = {'like': item['like'][i]}
            reward = {'reward': item['reward'][i]}
            subject = {'subject': item['subject'][i]}
            line = line + json.dumps(title, ensure_ascii=False)
            line = line + json.dumps(author, ensure_ascii=False)
            line = line + json.dumps(post_time, ensure_ascii=False)
            line = line + json.dumps(read, ensure_ascii=False)
            line = line + json.dumps(comment, ensure_ascii=False)
            line = line + json.dumps(like, ensure_ascii=False)
            line = line + json.dumps(reward, ensure_ascii=False)
            line = line + json.dumps(subject, ensure_ascii=False) + '\n'

        self.file.write(line)

    def close_spider(self, spider):
        self.file.close()

当然，不要忘了配置settings.py

BOT_NAME = 'jianshu'

SPIDER_MODULES = ['jianshu.spiders']
NEWSPIDER_MODULE = 'jianshu.spiders'
ITEM_PIPELINES = {
    'jianshu.pipelines.JianshuPipeline': 300,
}

USER_AGENT = 'Mozilla/5.0 (Windows NT 6.1; Win64; x64)' \
             'AppleWebKit/537.36 (KHTML, like Gecko)' \
             'Chrome/58.0.3029.96 Safari/537.36'

ROBOTSTXT_OBEY = True

目前程序由一些小bug，不知道该怎么改，先交作业。
主要是由于爬到的数据不能一一对应导致报错。