Scrapy支持通过实现一个自定义的过滤器中间件来支持URL自定义过滤。首先,您需要定义一个自定义的Middleware类,并实现process_request方法,在该方法中可以对请求的URL进行过滤。然后,将该Middleware类添加到Scrapy的DOWNLOADER_MIDDLEWARES配置中,确保它在整个下载流程中被调用。
以下是一个简单的示例,演示如何实现一个自定义的过滤器中间件来过滤URL:
```python
from scrapy import signals
from scrapy.downloadermiddlewares.httpproxy import HttpProxyMiddleware
class CustomFilterMiddleware(HttpProxyMiddleware):
def __init__(self, settings):
super().__init__(settings)
# 自定义的URL过滤规则
self.allowed_domains = settings.getlist('ALLOWED_DOMAINS')
@classmethod
def from_crawler(cls, crawler):
middleware = super(CustomFilterMiddleware, cls).from_crawler(crawler)
crawler.signals.connect(middleware.spider_opened, signal=signals.spider_opened)
return middleware
def spider_opened(self, spider):
self.allowed_domains.extend(getattr(spider, 'allowed_domains', []))
def process_request(self, request, spider):
if not any(domain in request.url for domain in self.allowed_domains):
self.logger.debug(f"URL {request.url} is not allowed by custom filter")
return None
return None
```
然后,在Scrapy的settings.py文件中添加以下配置:
```python
DOWNLOADER_MIDDLEWARES = {
'myproject.middlewares.CustomFilterMiddleware': 543,
}
ALLOWED_DOMAINS = ['example.com', 'example.org']
```
在这个示例中,CustomFilterMiddleware类继承自Scrapy内置的HttpProxyMiddleware,并在process_request方法中检查请求的URL是否属于ALLOWED_DOMAINS列表中的任何一个域名。如果不属于任何一个域名,则该请求将被过滤掉。
通过实现这样一个自定义的过滤器中间件,您可以灵活地定义URL的过滤规则,以满足您的需求。