更新

Python-100-Days/Day66-75/code/example05.py

@@ -0,0 +1,83 @@
+from urllib.error import URLError
+from urllib.request import urlopen
+
+import re
+import redis
+import ssl
+import hashlib
+import logging
+import pickle
+import zlib
+
+# Redis有两种持久化方案
+# 1. RDB
+# 2. AOF
+
+
+# 通过指定的字符集对页面进行解码(不是每个网站都将字符集设置为utf-8)
+def decode_page(page_bytes, charsets=('utf-8',)):
+    page_html = None
+    for charset in charsets:
+        try:
+            page_html = page_bytes.decode(charset)
+            break
+        except UnicodeDecodeError:
+            pass
+            # logging.error('[Decode]', err)
+    return page_html
+
+
+# 获取页面的HTML代码(通过递归实现指定次数的重试操作)
+def get_page_html(seed_url, *, retry_times=3, charsets=('utf-8',)):
+    page_html = None
+    try:
+        if seed_url.startswith('http://') or \
+                seed_url.startswith('https://'):
+            page_html = decode_page(urlopen(seed_url).read(), charsets)
+    except URLError as err:
+        logging.error('[URL]', err)
+        if retry_times > 0:
+            return get_page_html(seed_url, retry_times=retry_times - 1,
+                                 charsets=charsets)
+    return page_html
+
+
+# 从页面中提取需要的部分(通常是链接也可以通过正则表达式进行指定)
+def get_matched_parts(page_html, pattern_str, pattern_ignore_case=re.I):
+    pattern_regex = re.compile(pattern_str, pattern_ignore_case)
+    return pattern_regex.findall(page_html) if page_html else []
+
+
+# 开始执行爬虫程序
+def start_crawl(seed_url, match_pattern, *, max_depth=-1):
+    client = redis.Redis(host='1.2.3.4', port=6379, password='1qaz2wsx')
+    charsets = ('utf-8', 'gbk', 'gb2312')
+    logging.info('[Redis ping]', client.ping())
+    url_list = [seed_url]
+    visited_url_list = {seed_url: 0}
+    while url_list:
+        current_url = url_list.pop(0)
+        depth = visited_url_list[current_url]
+        if depth != max_depth:
+            page_html = get_page_html(current_url, charsets=charsets)
+            links_list = get_matched_parts(page_html, match_pattern)
+            for link in links_list:
+                if link not in visited_url_list:
+                    visited_url_list[link] = depth + 1
+                    page_html = get_page_html(link, charsets=charsets)
+                    if page_html:
+                        hasher = hashlib.md5()
+                        hasher.update(link.encode('utf-8'))
+                        zipped_page = zlib.compress(pickle.dumps(page_html))
+                        client.set(hasher.hexdigest(), zipped_page)
+
+
+def main():
+    ssl._create_default_https_context = ssl._create_unverified_context
+    start_crawl('http://sports.sohu.com/nba_a.shtml',
+                r'<a[^>]+test=a\s[^>]*href=["\'](.*?)["\']',
+                max_depth=2)
+
+
+if __name__ == '__main__':
+    main()