我想了解在实时情况下获取RSS订阅的最佳方法,而无需在内容未改变时下载整个订阅。语言不限,只是希望找到最好的方法。
ETag
和If-Modified-Since
HTTP头参数。以下是Python代码示例:etag = ... # etag of previous request
last_modifier = ... # time of last request
req = urllib2.Request(url)
if etag:
req.add_header("If-None-Match", etag)
if last_modified:
req.add_header("If-Modified-Since", last_modified)
opener = urllib2.build_opener(NotModifiedHandler())
url_handle = opener.open(req)
headers = url_handle.info()
if hasattr(url_handle, 'code') and url_handle.code == 304:
# no change happened
else:
# RSS Feed has changed