正好朋友有个爬虫的需求，拿来练习一下：

需求

根据朋友提供的appid列表，爬取回对应的app信息。

找到目标页面

chrome打开七麦官网：https://www.qimai.cn/，右上角有一个查询appid的输入框。

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输入appid后回车（举例：1279207754），会自动跳转到对应的app信息页：https://www.qimai.cn/app/rank/appid/1279207754/country/cn。

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分析页面

打开chrome调试工具，查看上图两处的element

image.png

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开始写代码

首先写一个无界面的selenium webdriver

from selenium import webdriver
from selenium.webdriver.common.by import By
from fake_useragent import UserAgent
import time

options = webdriver.ChromeOptions()
options.add_argument("user-agent=" + UserAgent().random)
# options.add_argument('--headless') # 无界面浏览
options.add_argument('--disable-gpu')
options.add_argument('--window-size=1366,768')
options.add_argument('disable-infobars')
options.add_argument('--no-sandbox')
driver = webdriver.Chrome(options=options)

然后打开目标页面，appid后面改成从文件里循环读取

url = 'https://www.qimai.cn/app/baseinfo/appid/{}/country/cn'
appid = '1279207754'
driver.get(url.format(appid))

爬取应用名称

time.sleep(5)
title = driver.find_element(By.CSS_SELECTOR, '.app-body .p-title').get_attribute('innerText')
print(title)

爬取应用详细信息

info_dict = {}
info_list = driver.find_elements(By.CSS_SELECTOR, '.appinfo-pkg .baseinfo-list li')
for ele in info_list:
    one_type = ele.find_element(By.CSS_SELECTOR, '.type').get_attribute('innerText')
    one_info = ele.find_element(By.CSS_SELECTOR, '.info').get_attribute('innerText')
    info_dict[one_type] = one_info
print(info_dict)
driver.quit()

本来以为会很顺利，结果遇到页面报错，网页直接跳到404页面！

image.png

第一次遇到这种情况，经过网上搜索，发现是网站有检测爬虫，使用的是navigator.webdriver的js判断。解决方法也简单，driver的赋值那里添加如下代码:

# 修改webdriver值
driver.execute_cdp_cmd('Page.addScriptToEvaluateOnNewDocument', {
    "source": "Object.defineProperty(navigator, 'webdriver', {get: () => undefined})"
})

这回浏览器顺利打开了目标页面，但是依然有报错
selenium.common.exceptions.NoSuchElementException: Message: no such element: Unable to locate element: {"method":"css selector","selector":".info"}
不难看出，这是one_info = ele.find_element(By.CSS_SELECTOR, '.info').get_attribute('innerText')这句代码出的错，应该是有些li里没有info，这里我们加个异常处理

try:
    one_type = ele.find_element(By.CSS_SELECTOR, '.type').get_attribute('innerText')
    one_info = ele.find_element(By.CSS_SELECTOR, '.info').get_attribute('innerText')
    info_dict[one_type] = one_info
except Exception as e:
    print(e)

这下可以正常输出信息了：

image.png

读取文件和写入文件

把朋友给的appid列表存到qimai_ids.txt文档里，使用open方法读取

with open('qimai_ids.txt', 'r', newline='') as f:
    appid_list = [line.strip() for line in f.readlines()]
    print(appid_list)

然后把应用信息写入到qimai.csv表格里

with open(self.csv_file, 'a', newline='') as f:
    # 生成csv操作对象
    writer = csv.writer(f)
    # 写入csv文件
    try:
        writer.writerow(app_info)
    except Exception as e:
        print(e)
        print('!!!写入失败：%s' % app_info[0])

注意，这里的app_info，是我把title和info_dict组合成一个新的list，具体代码见后面。
然后再写一个循环爬取方法，注意加上时间间隔，实测需要10s间隔，否则容易被检测到封禁IP。

完整代码

from selenium import webdriver
from selenium.webdriver.common.by import By
import time
import csv
import os
import random
from fake_useragent import UserAgent

options = webdriver.ChromeOptions()
options.add_argument("user-agent=" + UserAgent().random)
options.add_argument('--headless')  # 无界面浏览
options.add_argument('--disable-gpu')
options.add_argument('--window-size=1366,768')
options.add_argument('disable-infobars')
options.add_argument('--no-sandbox')

# 反爬
options.add_experimental_option('excludeSwitches', ['enable-automation'])
options.add_experimental_option('useAutomationExtension', False)

driver = webdriver.Chrome(options=options)
# 修改webdriver值
driver.execute_cdp_cmd('Page.addScriptToEvaluateOnNewDocument', {
    "source": "Object.defineProperty(navigator, 'webdriver', {get: () => undefined})"
})


class QimaiSpider(object):
    def __init__(self):
        self.csv_file = 'qimai.csv'
        self.url = 'https://www.qimai.cn/app/baseinfo/appid/{}/country/cn'
        self.record_list = []
        self.appid_list = []

        # 初始化表格
        csv_exists = os.path.exists(self.csv_file) and os.path.getsize(self.csv_file) != 0
        if not csv_exists:
            with open(self.csv_file, 'a', newline='') as f:
                print('csv表格不存在，初始化表格')
                # 生成csv操作对象
                writer = csv.writer(f)
                writer.writerow(['appid', 'BundleID', '名称', '开发者', '供应商', '发布日期', '更新日期', '版本', '价格', '年龄评级'])
        else:
            with open(self.csv_file, 'r', newline='') as f:
                reader = csv.DictReader(f)
                self.record_list = [row['appid'] for row in reader if row['BundleID'] and row['BundleID'] != '-']
                print('已加载成功数据 %d 个' % len(self.record_list))

        # 加载appid列表
        with open('qimai_ids.txt', 'r', newline='') as f:
            self.appid_list = [line.strip() for line in f.readlines() if line.strip() not in self.record_list]
            print('未加载成功数据 %d 个' % len(self.appid_list))

    def run(self):
        count = 0
        total = len(self.appid_list)
        for appid in self.appid_list:
            self.load_app_info(appid)
            count += 1
            rand = random.uniform(8.0, 10.0)
            print('已完成%d / %d，%ds后继续' % (count, total, int(rand)))
            if count < total:
                time.sleep(rand)
        driver.quit()

    def load_app_info(self, appid):
        print('---加载appid开始：%s' % appid)
        print(self.url.format(appid))
        driver.get(self.url.format(appid))

        time.sleep(5)

        try:
            info_dict = {}
            title = driver.find_element(By.CSS_SELECTOR, '.app-body .p-title').get_attribute('innerText')
            info_list = driver.find_elements(By.CSS_SELECTOR, '.appinfo-pkg .baseinfo-list li')
            for ele in info_list:
                try:
                    one_type = ele.find_element(By.CSS_SELECTOR, '.type').get_attribute('innerText')
                    one_info = ele.find_element(By.CSS_SELECTOR, '.info').get_attribute('innerText')
                    info_dict[one_type] = one_info
                except Exception as e:
                    print(e)
            bundle_id = info_dict.get('Bundle ID', '-')
            developer = info_dict.get('开发者', '-')
            supplier = info_dict.get('供应商', '-')
            release_date = info_dict.get('发布日期', '-')
            update_date = info_dict.get('更新日期', '-')
            version = info_dict.get('版本', '-')
            price = info_dict.get('价格', '-')
            age = info_dict.get('年龄评级', '-')

            app_info = [appid, bundle_id, title, developer, supplier, release_date, update_date, version, price, age]
            self.write_csv(app_info)
            print(app_info)
            print('===加载appid结束：%s' % appid)
        except Exception as e:
            print(e)
            print('!!!加载appid失败：%s' % appid)
            self.write_csv([appid, '-'])

    def write_csv(self, app_info):
        with open(self.csv_file, 'a', newline='') as f:
            # 生成csv操作对象
            writer = csv.writer(f)
            # 写入csv文件
            try:
                writer.writerow(app_info)
            except Exception as e:
                print(e)
                print('!!!写入失败：%s' % app_info[0])


if __name__ == '__main__':
    spider = QimaiSpider()
    spider.run()