这个爬虫我想分三期来写：
✅ 第一期写如何爬取汽车的车型信息；
✅ 第二期写如何爬取汽车的车评；
✅ 第三期写如何对车评嵌入情感分析结果，以及用简单的方法把数据插入mysql中；
技术基于scrapy框架、BERT语言模型、mysql数据库。

1 新建工程

scrapy的老三样，可以用命令创建工程

scrapy startproject car_spider

进入目录，创建爬虫

cd car_spider
scrapy genspider car dongchedi.com

这样scrapy就自动搭好了看框架，然后用开发工具打开就行了。

2 分页爬取车型

我们的爬取思路是先根据车型接口获取到所有的车型，然后根据汽车的详情接口去获取汽车详情数据。
获取车型的接口是post请求，带有分页参数的，所以可以这么处理:

class CarSpider(scrapy.Spider):
    name = 'car'
    allowed_domains = ['dongchedi.com']
    start_url = 'https://www.dongchedi.com/motor/pc/car/brand/select_series_v2?aid=1839&app_name=auto_web_pc'

    custom_settings = {
        'USER_AGENT': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 '
                      '(KHTML, like Gecko) Chrome/89.0.4389.114 Safari/537.36'
    }

    def __init__(self, *args, **kwargs):
        super(CarSpider, self).__init__(*args, **kwargs)
        self.item_count = 0  # 初始化计数器
        self.limit = 20  # 每页数据量
        self.current_page = 1  # 当前页码

    def start_requests(self):
        """首次发送 POST 请求"""
        formdata = {
            'page': str(self.current_page),
            'limit': str(self.limit),
        }
        yield scrapy.FormRequest(
            url=self.start_url,
            formdata=formdata,
            callback=self.parse
        )
    def parse(self, response):
        """解析分页数据并提取信息"""
        data = json.loads(response.body)
        series_list = data['data']['series']
        series_count = data['data']['series_count']  # 总数据量
        total_pages = (series_count // self.limit) + 1  # 计算总页数

        # 处理当前页的数据
        for car in series_list:
            car_id = car['concern_id']
            detail_url = f'https://www.dongchedi.com/motor/car_page/m/v1/series_all_json/?series_id={car_id}&city_name=武汉&show_city_price=1&m_station_dealer_price_v=1'
            yield scrapy.Request(url=detail_url, callback=self.parse_detail)

        # 如果还有下一页，继续发送请求
        if self.current_page < total_pages:
            self.current_page += 1
            formdata = {
                'page': str(self.current_page),
                'limit': str(self.limit),
            }
            yield scrapy.FormRequest(
                url=self.start_url,
                formdata=formdata,
                callback=self.parse
            )

3 爬取车型详细信息

获取到car[‘concern_id’]之后，就根据这个利用parse_detail去处理详情信息，获取到之后传给Item、pipeline

 def parse_detail(self, response):
        """解析汽车详细信息"""
        data = json.loads(response.body)
        series_all = data.get('data', {})
        cover_img = series_all.get('cover_url')
        brand_name = series_all.get('brand_name')
        series_id = series_all.get('series_id')
        online_models = series_all.get('online', [])

        for model in online_models:
            model_info = model['info']
            try:
                series_name = model_info['name']
                car_name = model_info['series_name']
                price_info = model_info['price_info']
                dealer_price = price_info.get('official_price', 'N/A')
                car_id = model_info.get('car_id')
                owner_price_summary = model_info.get('owner_price_summary', {})
                naked_price_avg = owner_price_summary.get('naked_price_avg', 'N/A')

                # 创建Item实例
                item = DongchediItem()
                item['name'] = f"{car_name}-{series_name}"
                item['dealer_price'] = dealer_price
                item['naked_price_avg'] = naked_price_avg
                item['brand_name'] = brand_name
                item['cover_img'] = cover_img
                item['series_id'] = series_id
                item['car_id'] = car_id
                self.item_count += 1  # 增加计数器
                # 返回item，保存到数据库或文件
                yield item

4 爬取结束给出统计信息

爬虫结束后给出统计信息，看看爬取了多少个数据，这里用紫色的字体:

    def closed(self, reason):
        """爬虫结束时调用"""
        purple_text = f"\033[95m总共爬取了 {self.item_count} 个 item\033[0m"
        self.logger.info(purple_text)

5 items 和 pipeline

实际上这个接口可以获取非常多的信息，这边写的比较简单，pipeline的处理也省略了，就进行一个打印：
items

class DongchediItem(scrapy.Item):
    name = scrapy.Field()
    dealer_price = scrapy.Field()
    naked_price_avg = scrapy.Field()
    brand_name = scrapy.Field()
    cover_img = scrapy.Field()
    series_id = scrapy.Field()
    car_id = scrapy.Field()

pipelines，注意在settings.py里激活一下

class DongchediPipeline:
    def process_item(self, item, spider):
        # 可以添加保存数据库或文件的逻辑
        print(item)
        return item

5 运行结果

运行一圈，发现爬取到了12565个车的数据。