前置知识

1/3乐观锁

2/3 Scrapy流程(非全部)

3/3 关于付费代理

我用的"快代理", 1000个ip, 每个ip1min的有效期, 你用的时候, 把你的链接, 用户名填上去就行

设置代理IP 🔒

• & 帮助文档: ①meta ②meta#proxy
• $ 语法: ①proxy的设置: Request对象中有个meta属性, 其下有个proxy属性, request.meta['proxy']="http://2.2.3.3:4324" ②download-timeout属性
• ! 卡点: Scrapy的异步是, 将所有的请求(近乎)同一时刻发出, 所以需要一个"版本锁"/"乐观锁"的思想(Redis的锁)

1.不可重用, 同步的思路

# Version_1: 因为异步延迟问题, 导致的ip复用失败
class IpDownloaderMiddleware:
    def __init__(self):
        # self.current_proxy_ip = self.get_proxy_ip()  # 初始化当前代理IP
        self.current_proxy_ip = "http://3.3.3.3:3333"  # 模拟ip失效

    @classmethod
    def from_crawler(cls, crawler):
        s = cls()
        return s

    def process_request(self, request: Request, spider):
        request.meta['proxy'] = self.current_proxy_ip  # 使用当前代理IP
        request.meta['download_timeout'] = 1  # 1s内没有返回就超时
        return None

    def process_response(self, request: Request, response: Response, spider):
        if response.status != 200:
            print(f"请求失败: {request.url}, 状态码: {response.status}")
            self.current_proxy_ip = self.get_proxy_ip()  # 获取新的代理IP
            request.meta['proxy'] = self.current_proxy_ip  # 更新请求的代理IP
            return request  # 返回请求以重试
        return response

    def process_exception(self, request, exception, spider):
        print(f"请求 {request.url} 发生异常: {exception}")
        self.current_proxy_ip = self.get_proxy_ip()  # 获取新的代理IP
        request.meta['proxy'] = self.current_proxy_ip  # 更新请求的代理IP
        return request  # 返回请求以重试

    def get_proxy_ip(self):
        api_url = "换成你的付费ip代理地址"
        proxy_ip = requests.get(api_url).text
        username = "你的账号"
        password = "你的密码"
        return f"http://{username}:{password}@{proxy_ip}/"

2. 可重用单ip版本

# Version_2: 采用类似"版本锁"的思想, 构建复用单ip
#   大体思路: 一个ip就是一个版本, ①版本相同+报错=ip失效(需要获取新ip) ②版本不同+报错=ip未及时更新(更新版本即可,无需获取新ip)
class IpDownloaderMiddleware_V2:
    def __init__(self):
        # self.current_proxy_ip = self.get_proxy_ip()  # 初始化当前代理IP
        self.current_proxy_ip = "http://3.3.3.3:8923"  # 模拟ip失效

    @classmethod
    def from_crawler(cls, crawler):
        s = cls()
        return s

    def process_request(self, request: Request, spider):
        request.meta['proxy'] = self.current_proxy_ip  # 使用当前代理IP
        request.meta['download_timeout'] = 1  # 1s内没有返回就超时
        request.meta['max_retry_times'] = 3  # 最多尝试0次
        # 打印当前是第几次try
        if "retry_times" not in request.meta:
            request.meta['retry_times'] = 1
        print(f"url:{request.url}, {request.meta['retry_times']}/{request.meta['max_retry_times']}")
        return None

    def process_response(self, request: Request, response: Response, spider):
        if response.status != 200:
            self.check_version(request)
            return request
        return response

    def process_exception(self, request, exception, spider):
        if isinstance(exception, twisted.internet.error.TimeoutError):
            self.check_version(request)
            return request

    def check_version(self, request):
        # 检测版本
        # case1:版本相同,意味着ip失效, 需要新的ip
        if request.meta['proxy'] == self.current_proxy_ip:
            self.current_proxy_ip = self.get_proxy_ip()  # 更新ip
            request.meta['proxy'] = self.current_proxy_ip
            print("获取新ip成功!!!")
        # case2: 版本不同,意味着未及时更新ip
        else:
            print("ip未及时更新,已正确赋值新ip")
            request.meta['proxy'] = self.current_proxy_ip

    def get_proxy_ip(self):
        api_url = "换成你的付费ip代理地址"
        proxy_ip = requests.get(api_url).text
        username = "你的账号"
        password = "你的密码"
        return f"http://{username}:{password}@{proxy_ip}/"

3. 可复用ip代理池

# Version_3: 同Version_2的思想, 构建ip池
class IpDownloaderMiddleware_V3:
    def __init__(self):
        self.pool_size = 5
        self.proxy_ip_pool = [f"http://3.3.3.3:333{i}" for i in range(self.pool_size)]  # 模拟失效ip
        # self.proxy_ip_pool = [self.get_proxy_ip() for _ in range(self.pool_size)]  # 初始化当前代理IP

    @classmethod
    def from_crawler(cls, crawler):
        s = cls()
        return s

    def process_request(self, request: Request, spider):
        request.meta['proxy'] = random.choice(self.proxy_ip_pool)  # 使用当前代理IP
        request.meta['download_timeout'] = 1  # 1s内没有返回就超时
        request.meta['max_retry_times'] = 3  # 最多尝试0次
        # 打印当前是第几次try
        if "retry_times" not in request.meta:
            request.meta['retry_times'] = 1
        print(f"url:{request.url}, {request.meta['retry_times']}/{request.meta['max_retry_times']}")
        return None

    def process_response(self, request: Request, response: Response, spider):
        if response.status != 200:
            self.check_version(request)
            return request
        return response

    def process_exception(self, request, exception, spider):
        if isinstance(exception, twisted.internet.error.TimeoutError):
            self.check_version(request)
            return request

    def check_version(self, request):
        # 检测版本
        # case1:版本相同[在ip池里有],意味着ip失效, 需要新的ip
        if request.meta['proxy'] in self.proxy_ip_pool:
            # 更新ip
            self.proxy_ip_pool.remove(request.meta['proxy'])  # 删除错误版本
            self.proxy_ip_pool.append(self.get_proxy_ip())  # 相当于替换

            request.meta['proxy'] = random.choice(self.proxy_ip_pool)
            print("获取新ip成功!!!")
        # case2: 版本不同,意味着未及时更新ip
        else:
            request.meta['proxy'] = random.choice(self.proxy_ip_pool)
            print("ip未及时更新,已正确赋值新ip")
        print(f"当前代理池:{self.proxy_ip_pool}")

    def get_proxy_ip(self):
        api_url = "换成你的付费ip代理地址"
        proxy_ip = requests.get(api_url).text
        username = "你的账号"
        password = "你的密码"
        return f"http://{username}:{password}@{proxy_ip}/"