{"id":179,"date":"2016-04-19T11:34:24","date_gmt":"2016-04-19T03:34:24","guid":{"rendered":"http:\/\/www.5x44.cn\/?p=179"},"modified":"2016-04-19T11:34:24","modified_gmt":"2016-04-19T03:34:24","slug":"%e7%ac%ac%e5%8d%81%e4%b8%80%e7%ab%a0-%e6%96%87%e4%bb%b6","status":"publish","type":"post","link":"https:\/\/www.5x44.cn\/?p=179","title":{"rendered":"\u7b2c\u5341\u4e00\u7ae0 \u6587\u4ef6"},"content":{"rendered":"<p>\uff081\uff09\u5728pythonk \u4e2d\u6253\u5f00\u6587\u4ef6\u975e\u5e38\u7684\u7b80\u5355\uff1a<\/p>\n<p>a_file = open(&#8216;examples\/chinese.txt&#8217;, encoding=&#8217;utf-8&#8242;)<\/p>\n<ol>\n<li>\u4e0d\u4ec5\u4ec5\u662f\u6587\u4ef6\u540d\uff0c\u5b83\u8fd8\u5305\u542b\u4e86\u6587\u4ef6\u5939\u8def\u5f84\u3002\u53ef\u4ee5\u5199\u76f8\u5bf9\u76ee\u5f55\u6216\u7edd\u5bf9\u76ee\u5f55\u3002<\/li>\n<li>\u8def\u5f84\u7531\u659c\u7ebf\u5206\u9694\uff0cWINDOWS\uff08\u53cd\u659c\u7ebf\\\uff09\u548cMAX OS X\u3001LINUX\uff08\u659c\u7ebf\/\uff09\u7684\u4e0d\u540c\uff0c\u4f46python\u4e2d\u4f7f\u7528\u659c\u7ebf\u53ef\u4ee5\u5f88\u597d\u7684\u5de5\u4f5c\u5728windows\u548clinux\u4e2d\u3002<\/li>\n<li>\u5982\u679c\u8def\u5f84\u4e0d\u4ee5\u76d8\u7b26\u6216\u659c\u7ebf\u5f00\u5934\uff0c\u90a3\u4e48\u8fd9\u4e2a\u8def\u5f84\u662f\u76f8\u5bf9\u8def\u5f84\u3002<\/li>\n<li>\u6240\u6709\u5f53\u524d\u6d41\u884c\u7684\u64cd\u4f5c\u7cfb\u7edf\u4f7f\u7528unicode\u5b58\u50a8\u6587\u4ef6\u540d\u5b57\u548c\u8def\u5f84\u3002python3\u5b8c\u5168\u652f\u6301\u975eASCII\u8def\u5f84\u3002<\/li>\n<li>\u8def\u5f84\u4e5f\u53ef\u4ee5\u4e0d\u662f\u672c\u5730\u6587\u4ef6\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528\u7f51\u7edc\u9a71\u52a8\u5668\u8def\u5f84\u3002\u8fd9\u4e2a\u6587\u4ef6\u53ef\u4ee5\u662f\u4e00\u4e2a\u865a\u62df\u6587\u4ef6\u7cfb\u7edf\u865a\u6784\u7684\u6587\u4ef6\u3002\u53ea\u8981\u4f60\u7684\u7cfb\u7edf\u5141\u8bb8\u4f60\u8bbf\u95ee\u5b83\u3002<\/li>\n<li>encoding\u6307\u5b9a\u7528\u4ec0\u4e48\u7f16\u7801\u65b9\u5f0f\u6253\u5f00\u6587\u4ef6\u3002<\/li>\n<\/ol>\n<p>\uff082\uff09\u5b57\u7b26\u7f16\u7801<\/p>\n<p>\u5b57\u7b26\u76f8\u5bf9\u4e8e\u5b57\u8282\u662f\u62bd\u8c61\u7684\u3002\u4e00\u4e2a\u5b57\u7b26\u4e32\u662f\u4e00\u4e2aunicode\u5b57\u7b26\u5e8f\u5217\u3002\u4f46\u662f\u78c1\u76d8\u4e0a\u7684\u6587\u4ef6\u4e0d\u662f\u4e00\u4e32unicode\u5b57\u7b26\uff1b\u5728\u78c1\u76d8\u4e0a\u7684\u6587\u4ef6\u662f\u4e00\u4e32\u5b57\u8282\u7684\u6392\u5e8f\u3002\u6240\u4ee5\u5f53python\u8bfb\u78c1\u76d8\u6587\u4ef6\u65f6\u5982\u4f55\u628a\u5b83\u8f6c\u6362\u6210\u4e00\u4e32\u5b57\u7b26\uff1f\u8fd9\u5c31\u8981\u6839\u636e\u5b57\u7b26\u7f16\u7801\u65b9\u5f0f\u3002<\/p>\n<p>\u5982\u679c\u6ca1\u6709\u6307\u5b9a\u7f16\u7801\u65b9\u5f0f\uff0c\u90a3\u4e48\u4f1a\u4f7f\u7528\u7cfb\u7edf\u9ed8\u8ba4\u7684\u7f16\u7801\u65b9\u5f0f\u3002<\/p>\n<p>\uff083\uff09\u6d41\u5bf9\u8c61<\/p>\n<p>\u73b0\u5728\u6211\u4eec\u5df2\u7ecf\u77e5\u9053python\u5185\u5efa\u51fd\u6570\u88ab\u79f0\u4f5copen()\u3002open()\u51fd\u6570\u8fd4\u56de\u4e00\u4e2a<strong>\u6d41\u5bf9\u8c61<\/strong>\uff0c\u5b83\u6709\u4e00\u4e9b\u64cd\u63a7\u5b57\u7b26\u7684\u65b9\u6cd5\u548c\u5c5e\u6027\uff0c\u7528\u4e8e\u83b7\u5f97\u4fe1\u606f\u3002<\/p>\n<p>\uff084\uff09\u4ece\u4e00\u4e2a\u6587\u4ef6\u4e2d\u8bfb\u6570\u636e<\/p>\n<p><code> &gt;&gt;&gt; a_file = open('examples\/chinese.txt', encoding='utf-8')<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read() \u2460<\/code><br \/>\n<code>'Dive Into Python \u662f\u4e3a\u6709\u7ecf\u9a8c\u7684\u7a0b\u5e8f\u5458\u7f16\u5199\u7684\u4e00\u672c Python \u4e66\u3002\\n'<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read() \u2461<\/code><br \/>\n<code>''<\/code><\/p>\n<ol>\n<li>\u4e00\u4f46\u4f60\u4f7f\u7528\u6b63\u786e\u7684\u7f16\u7801\u6253\u5f00\u4e86\u4e00\u4e2a\u6587\u4ef6\uff0c\u4f7f\u7528read()\u53ef\u4ee5\u8bfb\u5b83\u7684\u5185\u5bb9\uff0cread()\u8fd4\u56de\u4e00\u4e2a\u5b57\u7b26\u4e32\u3002<\/li>\n<li>\u5f53\u5230\u8fbe\u6587\u4ef6\u7ed3\u5c3e\u65f6\uff0c\u7ee7\u7eed\u8bfb\u4e0b\u53bb\u4e0d\u4f1a\u51fa\u9519\uff0c\u53ea\u4f1a\u8fd4\u56de\u4e00\u4e2a\u7a7a\u5b57\u7b26\u4e32\u3002<\/li>\n<\/ol>\n<p>\u5982\u679c\u8981\u91cd\u8bfb\u4e00\u4e2a\u6587\u4ef6\u600e\u4e48\u529e\uff1f<\/p>\n<p><code> &gt;&gt;&gt; a_file.read() \u2460<\/code><br \/>\n<code>''<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.seek(0) \u2461<\/code><br \/>\n<code>0<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read(16) \u2462<\/code><br \/>\n<code>'Dive Into Python'<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read(1) \u2463<\/code><br \/>\n<code>' '<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read(1)<\/code><br \/>\n<code>'\u662f'<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.tell() \u2464<\/code><br \/>\n<code>20<\/code><\/p>\n<ol>\n<li>\u5728\u6587\u4ef6\u7684\u7ed3\u5c3e\u4f7f\u7528read()\uff0c\u53ea\u4f1a\u8fd4\u56de\u7a7a\u5b57\u7b26\u4e32\u3002<\/li>\n<li>seek()\u65b9\u6cd5\u79fb\u52a8\u5230\u6587\u4ef6\u7684\u6307\u5b9a\u5b57\u8282\u4f4d\u7f6e\u3002<\/li>\n<li>read()\u53ef\u4ee5\u5e26\u4e00\u4e2a\u53ef\u9009\u7684\u53c2\u6570\u6765\u6307\u5b9a\u8981\u8bfb\u591a\u5c11\u4e2a\u5b57\u7b26\u3002<\/li>\n<li>\u53ea\u8981\u4f60\u559c\u6b22\uff0c\u751a\u81f3\u4f60\u53ef\u4ee5\u4e00\u6b21\u53ea\u8bfb\u4e00\u4e2a\u5b57\u7b26\u3002<\/li>\n<li>tell()\u8fd4\u56de\u5f53\u524d\u5b57\u8282\u4f4d\u7f6e\u3002<\/li>\n<\/ol>\n<p>\u4f60\u5e94\u8be5\u770b\u5230seek()\u548ctell()\u65b9\u6cd5\u4e00\u76f4\u4ee5\u5b57\u8282\u4e3a\u5355\u4f4d\uff0c\u4f46\u662f\u53ea\u8981\u4f60\u4ee5\u6587\u4ef6\u7684\u65b9\u5f0f\u6253\u5f00\uff0cread()\u65b9\u6cd5\u4ee5\u5b57\u7b26\u4e3a\u5355\u4f4d\u3002\u4e2d\u6587\u5b57\u7b26\u5728utf-8\u7f16\u7801\u4e2d\u9700\u8981\u591a\u4e2a\u5b57\u8282\u3002\u800c\u6bcf\u4e2a\u82f1\u8bed\u5b57\u7b26\u5728\u6587\u4ef6\u4e2d\u53ea\u8981\u4e00\u4e2a\u5b57\u8282\uff0c\u6240\u4ee5\u4e0d\u8981\u88ab\u8bef\u5bfc\u4e86\uff01\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48\u4f8b\u5b50\u4e2d\u8bfb\u4e8616+1+1\u4e2a\u5b57\u7b26\u540e\u5374\u5728\u7b2c20\u4e2a\u5b57\u8282\u5904\u7684\u539f\u56e0\u3002<\/p>\n<p>\u770b\u4e00\u4e0b\u8fd9\u4e2a\u4f8b\u5b50\uff1a<\/p>\n<p><code> &gt;&gt;&gt; a_file.seek(18) \u2460<\/code><br \/>\n<code>18<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read(1) \u2461<\/code><br \/>\n<code>Traceback (most recent call last):<\/code><br \/>\n<code>File \"&lt;pyshell#12&gt;\", line 1, in &lt;module&gt;<\/code><br \/>\n<code>a_file.read(1)<\/code><br \/>\n<code>File \"C:\\Python31\\lib\\codecs.py\", line 300, in decode<\/code><br \/>\n<code>(result, consumed) = self._buffer_decode(data, self.errors, final)<\/code><br \/>\n<code>UnicodeDecodeError: 'utf8' codec can't decode byte 0x98 in position 0: unexpected code byte<\/code><\/p>\n<ol>\n<li>\u79fb\u52a8\u5230\u7b2c18\u4e2a\u5b57\u8282\u5904\u3002<\/li>\n<li>\u4e3a\u4ec0\u4e48\u4f1a\u51fa\u9519\uff1f\u56e0\u4e3a\u7b2c18\u4e2a\u5b57\u8282\u4e0d\u662f\u4e00\u4e2a\u5b8c\u6574\u7684\u5b57\u7b26\uff0c\u6700\u8fd1\u7684\u5b57\u7b26\u662f\u5728\u7b2c17\u4e2a\u5b57\u8282\u5904\u5f00\u59cb\u7684\u3002<strong>\u5c1d\u8bd5\u5728\u4e00\u4e2a\u5b57\u7b26\u4e2d\u95f4\u8bfb\u4f1a\u51fa\u9519\u3002<\/strong><\/li>\n<\/ol>\n<p>\uff085\uff09\u5173\u95ed\u6587\u4ef6<\/p>\n<p>\u6253\u5f00\u7684\u6587\u4ef6\u5360\u7528\u4e86\u7cfb\u7edf\u7684\u8d44\u6e90\uff0c\u8fd9\u4f9d\u8d56\u4e8e\u6253\u5f00\u6587\u4ef6\u7684\u6a21\u5f0f\uff0c\u53ef\u80fd\u4f1a\u5bfc\u81f3\u522b\u7684\u7a0b\u5e8f\u65e0\u6cd5\u6253\u5f00\u5b83\u4eec\u3002\u5728\u4f7f\u7528\u5b8c\u6587\u4ef6\u540e\u5173\u95ed\u5b83\u4eec\uff0c\u8fd9\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002\u65b9\u6cd5\u5c31\u662f\u5728\u6d41\u5bf9\u8c61\u4e0a\u4f7f\u7528close()\u65b9\u6cd5\u3002<\/p>\n<ol>\n<li>\u8bfb\u5df2\u7ecf\u5173\u95ed\u7684\u6587\u4ef6\uff0c\u4f1a\u5f15\u53d1IOError\u5f02\u5e38\u3002<\/li>\n<li>\u540c\u6837\u4e0d\u80fdseek<\/li>\n<li>\u56e0\u4e3a\u6587\u4ef6\u5df2\u7ecf\u5173\u95ed\u4e86\uff0c\u6240\u4ee5\u6ca1\u6709\u5f53\u524d\u4f4d\u7f6e\uff0c\u4e5f\u5c31\u662f\u4e0d\u80fd\u7528tell()\u65b9\u6cd5\uff01<\/li>\n<li>\u5728\u4e00\u4e2a\u5df2\u7ecf\u5173\u95ed\u7684\u6587\u4ef6\u4e0a\u8c03\u7528close()\u4e0d\u4f1a\u51fa\u9519\u3002<\/li>\n<li>\u6d41\u5bf9\u8c61\u6709\u4e00\u4e2a\u5f88\u6709\u7528\u7684\u5c5e\u6027\u2014\u2014closed\uff01\u5b83\u7528\u6765\u786e\u5b9a\u6587\u4ef6\u5df2\u7ecf\u5173\u95ed\u4e86\uff0c\u5b83\u662f\u4e00\u4e2a\u5e03\u5c14\u503c\u3002<\/li>\n<\/ol>\n<p>\uff086\uff09\u81ea\u52a8\u5173\u95ed\u6587\u4ef6<\/p>\n<p>\u5982\u679c\u663e\u793a\u8c03\u7528close()\u4e4b\u524d\u51fa\u73b0\u4e86BUG\u6216\u7a0b\u5e8f\u5d29\u6e83\u4e86\uff01\u90a3\u6587\u4ef6\u70b9\u7528\u7684\u8d44\u6e90\u53ef\u80fd\u4f1a\u5728\u7cfb\u7edf\u4e2d\u7ee7\u7eed\u4fdd\u5b58\u4e00\u6bb5\u65f6\u95f4\u3002\u5728python2\u4e2d\u7684\u89e3\u51b3\u65b9\u6848\u662f\u4f7f\u7528try&#8230;finally\u5757\u3002\u8fd9\u5728python3\u4e2d\u4e5f\u53ef\u4ee5\u7528\uff0c\u81ea\u4ecepython2.6\u5f15\u5165\u4e86with\u8bed\u53e5\u540e\uff0c\u4f7f\u8fd9\u53d8\u7684\u66f4\u7b80\u5355\u4e86\u3002<\/p>\n<p><code> with open('examples\/chinese.txt', encoding='utf-8') as a_file:<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 a_file.seek(17)<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 a_character = a_file.read(1)<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 print(a_character)<\/code><\/p>\n<p>\u4e0a\u9762\u8fd9\u6bb5\u7a0b\u5e8f\u4f7f\u7528open()\u6253\u5f00\u4e86\u4e00\u4e2a\u6587\u4ef6\uff0c\u4f46\u4e0d\u9700\u8981\u4f7f\u7528close()\u5173\u95ed\u6587\u4ef6\u3002with\u8bed\u53e5\u5f00\u59cb\u4e86\u4e00\u4e2a\u4ee3\u7801\u5757\uff0c\u5c31\u50cfif\u6216for\u8bed\u53e5\u4e00\u6837\uff0c\u4f7f\u7528a_file\u505a\u4e3aopen()\u51fd\u6570\u8fd4\u56de\u7684\u6d41\u5bf9\u8c61\u3002\u6240\u6709\u6d41\u5bf9\u8c61\u65b9\u6cd5\u90fd\u662f\u53ef\u4ee5\u4f7f\u7528\u5728\u8fd9\u4e2a\u53d8\u91cf\u4e0a\u2014\u2014seek(),read(), \u7b49\u7b49\u3002\u5f53with\u8bed\u53e5\u5757\u7ed3\u675f\u65f6python\u81ea\u52a8\u8c03\u7528\u6d41\u5bf9\u8c61\u4e0a\u7684close()\u65b9\u6cd5\u3002\u5b83\u7684\u4f18\u70b9\u662f\u65e0\u8bba\u4ec0\u4e48\u8bf7\u6b3e\u90fd\u80fd\u81ea\u52a8\u7684\u8c03\u7528close()\uff0c\u65e0\u8bba\u662f\u5d29\u6e83\u8fd8\u662f\u5f02\u5e38\u3002<\/p>\n<p>\u4ece\u6280\u672f\u4e0a\u8bb2\uff0cwith\u8bed\u53e5\u521b\u5efa\u4e86\u201c\u8fd0\u884c\u65f6\u523b\u7684\u4e0a\u4e0b\u6587\u201d\u3002\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\u6d41\u5bf9\u8c61\u505a\u4e3a\u201c\u4e0a\u4e0b\u6587\u7ba1\u7406\u5668\u201d\u3002python\u521b\u5efaa_file\u6d41\u5bf9\u8c61\u5e76\u4e14\u544a\u8bc9\u5b83\uff0c\u5b83\u6b63\u5728\u8fdb\u5165\u4e00\u4e2a\u201c\u8fd0\u884c\u65f6\u523b\u7684\u4e0a\u4e0b\u6587\u201d\u3002\u5f53\u79bb\u5f00with\u5757\u65f6\uff0c\u6d41\u5bf9\u8c61\u8c03\u7528\u81ea\u5df1\u7684close()\u65b9\u6cd5\u5173\u95ed\u201c\u4e0a\u4e0b\u6587\u201d\u3002<\/p>\n<p>\uff087\uff09\u4e00\u6b21\u8bfb\u53d6\u4e00\u884c\u6570\u636e<\/p>\n<p>\u4e0d\u540c\u7684\u7cfb\u7edf\u6709\u4e0d\u540c\u7684\u6362\u884c\u7b26\uff0c\u7528python\u8bfb\u53d6\u4e00\u884c\uff0c\u4e0d\u9700\u8981\u624b\u52a8\u8bbe\u7f6e\u6362\u884c\u7b26\uff0cpython\u53ef\u4ee5\u81ea\u52a8\u5904\u7406\u4e00\u884c\u7684\u7ed3\u675f\u7b26\u3002\u4e0d\u8fc7\u5982\u679c\u4f60\u624b\u52a8\u8bbe\u7f6e\u544a\u8bc9python\u6362\u884c\u7b26\u662f\u4ec0\u4e48\uff0c\u8981\u5728open()\u51fd\u6570\u4e2d\u4f7f\u7528newline\u53c2\u6570\u3002<\/p>\n<p><code> line_number = 0<\/code><br \/>\n<code>with open('examples\/favorite-people.txt', encoding='utf-8') as a_file: \u2460<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 for a_line in a_file: \u2461<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 line_number += 1<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 print('{:&gt;4} {}'.format(line_number, a_line.rstrip())) \u2462<\/code><\/p>\n<ol>\n<li>\u4f7f\u7528with\u6a21\u5f0f\u5b89\u5168\u7684\u6253\u5f00\u4e00\u4e2a\u6587\u6863\u3002<\/li>\n<li>\u5728for\u5faa\u73af\u4e2d\u8bfb\u6587\u4ef6\u4e00\u6b21\u4e00\u884c\u3002\u6d41\u5bf9\u8c61\u540c\u6837\u4e5f\u662f\u4e00\u4e2a\u8fed\u4ee3\u5668\u5b83\u53ef\u4ee5\u6bcf\u6b21\u4ece\u6587\u4ef6\u4e2d\u83b7\u5f97\u4e00\u884c\u6570\u636e\u3002<\/li>\n<li>{:&gt;4}\u610f\u5473\u7740\u6253\u5370\u8fd9\u4e2a\u53c2\u6570\u53f3\u8fb9\u7559\u51fa4\u4e2a\u7a7a\u683c\u4f4d\uff0c\u800c\u5b57\u7b26\u4e32\u7684rstrip()\u610f\u5473\u7740\u79fb\u9664\u7ed3\u5c3e\u7684\u7a7a\u683c\uff08\u5305\u542b\u6362\u884c\u7b26\uff09\u3002<\/li>\n<\/ol>\n<p>\uff088\uff09\u5411\u6587\u4ef6\u4e2d\u5199\u5165<\/p>\n<p>\u5199\u5165\u548c\u8bfb\u53d6\u4e00\u6837\u7b80\u5355\uff0c\u5199\u5165\u6587\u4ef6\u65f6\uff0c\u6709\u4e24\u79cd\u6587\u4ef6\u6253\u5f00\u6a21\u5f0f\uff1a<\/p>\n<ul>\n<li>\u201d\u5199\u201c\u6a21\u5f0f\uff1a\u4f1a\u8986\u76d6\u539f\u6587\u4ef6\u3002\u4f20\u9012<code>mode='w'<\/code>\u7ed9<code>open()<\/code>\u51fd\u6570\u3002<\/li>\n<li>\u201d\u8ffd\u52a0\u201c\u6a21\u5f0f\uff1a\u4f1a\u6dfb\u52a0\u6570\u636e\u5230\u6587\u4ef6\u7684\u7ed3\u5c3e\u3002\u4f20\u9012<code>mode='a'<\/code>\u7ed9<code>open()<\/code>\u51fd\u6570\u3002<\/li>\n<\/ul>\n<p>\u5982\u679c\u6587\u4ef6\u4e0d\u5b58\u5728\uff0c\u90a3\u4e48\u4f1a\u521b\u5efa\u4e00\u4e2a\u6587\u4ef6\u3002\u5e94\u8be5\u4e00\u76f4\u4fdd\u6301\u7740\u5199\u5b8c\u540e\u7acb\u5373\u5173\u95ed\u6587\u4ef6\uff0c\u53bb\u91ca\u653e\u6587\u4ef6\u53e5\u67c4\u5e76\u4e14\u786e\u5b9a\u6570\u636e\u5df2\u7ecf\u5199\u5165\u5230\u78c1\u76d8\u4e86\u3002<\/p>\n<p><code> &gt;&gt;&gt; with open('test.log', mode='w', encoding='utf-8') as a_file: \u2460<\/code><br \/>\n<code>...\u00a0\u00a0\u00a0\u00a0 a_file.write('test succeeded') \u2461<\/code><br \/>\n<code>&gt;&gt;&gt; with open('test.log', encoding='utf-8') as a_file:<\/code><br \/>\n<code>...\u00a0\u00a0\u00a0\u00a0 print(a_file.read())<\/code><br \/>\n<code>test succeeded<\/code><br \/>\n<code>&gt;&gt;&gt; with open('test.log', mode='a', encoding='utf-8') as a_file: \u2462<\/code><br \/>\n<code>...\u00a0\u00a0\u00a0\u00a0 a_file.write('and again')<\/code><br \/>\n<code>&gt;&gt;&gt; with open('test.log', encoding='utf-8') as a_file:<\/code><br \/>\n<code>...\u00a0\u00a0\u00a0\u00a0 print(a_file.read())<\/code><br \/>\n<code>test succeededand again \u2463<\/code><\/p>\n<p>\uff089\uff09\u8fd8\u662f\u5b57\u7b26\u7f16\u7801\uff08\u8fd9\u56de\u662f\u5199\u5165\uff09<\/p>\n<p>\u4f60\u662f\u5426\u6ce8\u610f\u5230encoding\u53c2\u6570\u5728\u4e3a\u4e86\u5199\u5165\u800c\u6253\u5f00\u6587\u4ef6\u65f6\u88ab\u4f20\u9012\u7ed9open()\u51fd\u6570\uff1f<span style=\"color: #ff0000;\">\u8fd9\u5f88\u91cd\u8981\uff0c\u4e0d\u8981\u6254\u4e0b\u5b83<\/span>\uff01\uff01\u5c31\u50cf\u5728\u672c\u7ae0\u5f00\u5934\u5199\u7684\u90a3\u6837\uff0c\u6587\u4ef6\u4e2d\u4fdd\u5b58\u7684\u4e0d\u662f\u5b57\u7b26\u800c\u662f\u5b57\u8282\u3002\u53ef\u4ee5\u4ece\u6587\u4ef6\u4e2d\u8bfb\u51fa\u5b57\u7b26\u4e32\u7684\u539f\u97f3\u662f\uff0cencoding\u53c2\u6570\u6307\u5b9a\u4e86\u89e3\u7801\u65b9\u5f0f\u3002\u5199\u5165\u4e5f\u6709\u540c\u6837\u7684\u95ee\u9898\uff0c\u4e0d\u80fd\u4ee5\u5b57\u7b26\u65b9\u5f0f\u5199\u5165\u4e00\u4e2a\u6587\u4ef6\uff0c\u201c\u5b57\u7b26\u201d\u662f\u4e00\u79cd\u62bd\u8c61\u7684\u6982\u5ff5\uff01<\/p>\n<p>\uff0810\uff09\u4e8c\u8fdb\u5236\u6587\u4ef6<\/p>\n<p><code> &gt;&gt;&gt; an_image = open('examples\/beauregard.jpg', mode='rb') \u2460<\/code><br \/>\n<code>&gt;&gt;&gt; an_image.mode \u2461<\/code><br \/>\n<code>'rb'<\/code><br \/>\n<code>&gt;&gt;&gt; an_image.name \u2462<\/code><br \/>\n<code>'examples\/beauregard.jpg'<\/code><br \/>\n<code>&gt;&gt;&gt; an_image.encoding \u2463<\/code><br \/>\n<code>Traceback (most recent call last):<\/code><br \/>\n<code>File \"&lt;stdin&gt;\", line 1, in &lt;module&gt;<\/code><br \/>\n<code>AttributeError: '_io.BufferedReader' object has no attribute 'encoding'<\/code><\/p>\n<ol>\n<li>\u4ee5\u4e8c\u8fdb\u5236\u65b9\u5f0f\u6253\u5f00\u6587\u4ef6\uff0cmode=&#8217;b&#8217;\u3002<\/li>\n<li>\u4ee5\u4e8c\u8fdb\u5236\u65b9\u5de5\u6253\u5f00\u6587\u4ef6\u5f97\u5230\u7684\u6d41\u5bf9\u8c61\u6709\u4e00\u6837\u591a\u7684\u5c5e\u6027\uff0c\u5305\u542bmode\uff0c\u5b83\u6620\u5c04\u5230\u4f20\u5165open()\u51fd\u6570\u7684\u90a3\u4e2a\u503c\u3002<\/li>\n<li>\u4e8c\u8fdb\u5236\u6587\u4ef6\u4e00\u6837\u6709name\u5c5e\u6027\uff0c\u548c\u6587\u672c\u6d41\u6587\u4ef6\u7684name\u662f\u4e00\u6837\u7684\u3002<\/li>\n<li>\u6709\u4e00\u70b9\u4e0d\u540c\uff0c\u4e8c\u8fdb\u5236\u6d41\u5bf9\u8c61\u6ca1\u6709encoding\u5c5e\u6027\u3002\u56e0\u4e3a\u4e0d\u9700\u8981\u8f6c\u6362\u6210\u67d0\u79cd\u683c\u5f0f\u7684\u5b57\u7b26\uff0c\u6240\u4ee5\u6ca1\u6709encoding\u3002<\/li>\n<\/ol>\n<p>\u90a3\u5982\u4f55\u8bfb\u4e8c\u8fdb\u5236\u6587\u4ef6\u5462\uff1f<\/p>\n<p><code> # continued from the previous example<\/code><br \/>\n<code>&gt;&gt;&gt; an_image.tell()<\/code><br \/>\n<code>0<\/code><br \/>\n<code>&gt;&gt;&gt; data = an_image.read(3) \u2460<\/code><br \/>\n<code>&gt;&gt;&gt; data<\/code><br \/>\n<code>b'\\xff\\xd8\\xff'<\/code><br \/>\n<code>&gt;&gt;&gt; type(data) \u2461<\/code><br \/>\n<code>&lt;class 'bytes'&gt;<\/code><br \/>\n<code>&gt;&gt;&gt; an_image.tell() \u2462<\/code><br \/>\n<code>3<\/code><br \/>\n<code>&gt;&gt;&gt; an_image.seek(0)<\/code><br \/>\n<code>0<\/code><br \/>\n<code>&gt;&gt;&gt; data = an_image.read()<\/code><br \/>\n<code>&gt;&gt;&gt; len(data)<\/code><br \/>\n<code>3150<\/code><\/p>\n<ol>\n<li>\u548c\u6587\u672c\u6587\u4ef6\u4e00\u6837\u53ef\u4ee5\u8bfb\u4e8c\u8fdb\u5236\u6587\u4ef6\uff0c\u4e00\u6b21\u8bfb\u51fa\u4e00\u4e9b\uff01\u4f46\u662f\u8fd9\u548c\u6587\u672c\u6587\u4ef6\u5b8c\u5168\u4e0d\u4e00\u6837\uff01<\/li>\n<li>\u8bfb\u51fa\u7684\u662f\u5b57\u8282\u800c\u4e0d\u662f\u5b57\u7b26\u3002<\/li>\n<li>\u8fd9\u610f\u5473\u7740\u7edd\u5bf9\u4e0d\u4f1a\u6709\u610f\u6599\u4e4b\u5916\u7684\u672a\u5339\u914d\uff0c\u5982seek()\u5230\u4e00\u4e2a\u4e2d\u6587\u5b57\u7b26\u7684\u4e2d\u95f4\u800c\u5bfc\u81f3\u4e0d\u80fd\u8bfb\u51fa\uff0c\u6216\u662f\u56e0\u4e3a\u4e00\u4e2a\u4e2d\u6587\u5b57\u7b26\u5360\u7528\u4e86\u591a\u4e2a\u5b57\u8282\uff0c\u7528tell()\u5b9a\u4f4d\u5f53\u524d\u4f4d\u7f6e\u548c\u8bfb\u51fa\u7684\u5b57\u7b26\u6570\u4e0d\u7b26\u3002\u5728\u4e8c\u8fdb\u5236\u6587\u4ef6\u4e2dseek()\u548ctell()\u65b9\u6cd5\u8fd4\u56de\u7684\u5b57\u7b26\u6570\u5c31\u662f\u5b57\u8282\u6570\u3002<\/li>\n<\/ol>\n<p>\uff0811\uff09\u6765\u81ea\u975e\u6587\u4ef6\u6e90\u7684\u6d41\u5bf9\u8c61<\/p>\n<p>\u60f3\u8c61\u4e00\u4e0b\u4f60\u5199\u4e86\u4e00\u4e2a\u5e93\uff0c\u5e76\u4e14\u8fd9\u4e2a\u5e93\u4e2d\u7684\u4e00\u4e2a\u51fd\u6570\u6253\u7b97\u4ece\u4e00\u4e2a\u6587\u4ef6\u4e2d\u8bfb\u4e00\u4e9b\u6570\u636e\u3002\u8fd9\u4e2a\u51fd\u6570\u53ef\u4ee5\u7b80\u5355\u7684\u6253\u5f00\u4e00\u4e2a\u6587\u4ef6\uff0c\u8bfb\u5b83\uff0c\u5173\u95ed\u5b83\u3002\u4f46\u662f\u4f60\u6ca1\u6709\u8fd9\u4e48\u505a\uff0c\u800c\u662f\u4f60\u7684API\u4f7f\u7528\u4e86\u4e00\u4e2a<em>\u4efb\u610f\u7684\u6d41\u5bf9\u8c61\u3002<\/em><\/p>\n<p>\u5728\u8fd9\u4e2a\u7b80\u5355\u7684\u4f8b\u5b50\u4e2d\uff0c\u6d41\u5bf9\u8c61\u53ef\u4ee5\u7528read()\u8bfb\u51fa\u4efb\u4f55\u4e1c\u897f\u3002read()\u51fd\u6570\u6709\u4e00\u4e2a\u53ef\u9009\u7684\u53c2\u6570size\uff0c\u5b83\u6307\u5b9a\u4e86\u4e00\u6b21\u6700\u591a\u8bfb\u51fa\u591a\u5c11\u4e2a\u5b57\u7b26\uff0c\u5982\u679c\u6ca1\u6709\u8fd9\u4e2a\u53c2\u6570\uff0cread()\u4f1a\u8bfb\u51fa\u5168\u90e8\u5b57\u7b26\u505a\u4e3a\u4e00\u4e2a\u5b57\u7b26\u4e32\u8fd4\u56de\u3002<\/p>\n<p>\u8fd9\u542c\u8d77\u6765\u5341\u5206\u50cf\u4ece\u4e00\u4e2a\u771f\u5b9e\u6587\u4ef6\u6253\u5f00\u7684\u6d41\u5bf9\u8c61\u3002\u4f46\u4e0d\u540c\u7684\u662f\uff0c\u6211\u4eec<em>\u5e76\u6ca1\u6709\u9650\u5236\u8fd9\u662f\u4e00\u4e2a\u771f\u5b9e\u7684\u6587\u4ef6<\/em>\u3002\u8fd9\u4e2a\u8f93\u5165\u6e90\u53ef\u4ee5\u662f\u4efb\u53ef\u80fd\u88ab\u201c\u8bfb\u201d\u7684\u4e1c\u897f\uff1aweb\u9875\u9762\u3001\u5185\u5b58\u4e2d\u7684\u5b57\u7b26\u4e32\u3001\u751a\u81f3\u662f\u5176\u5b83\u7a0b\u5e8f\u7684\u8f93\u51fa\u3002\u53ea\u8981\u4f60\u7684\u7a0b\u5e8f\u6709\u4e00\u4e2a\u6d41\u5bf9\u8c61\u5e76\u4e14\u7b80\u5355\u7684\u8c03\u7528\u6d41\u5bf9\u8c61\u7684read()\u65b9\u6cd5\uff0c\u5c31\u53ef\u4ee5\u50cf\u5904\u7406\u6587\u672c\u6587\u4ef6\u4e00\u6837\u5904\u7406\u4efb\u4f55\u8f93\u5165\u6e90\uff0c\u4e0d\u9700\u8981\u4efb\u4f55\u7279\u522b\u7684\u4ee3\u7801\u53bb\u5904\u7406\u4e0d\u540c\u7c7b\u578b\u7684\u8f93\u5165\u3002<\/p>\n<p><code> &gt;&gt;&gt; a_string = 'PapayaWhip is the new black.'<\/code><br \/>\n<code>&gt;&gt;&gt; import io \u2460<\/code><br \/>\n<code>&gt;&gt;&gt; a_file = io.StringIO(a_string) \u2461<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read() \u2462<\/code><br \/>\n<code>'PapayaWhip is the new black.'<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read() \u2463<\/code><br \/>\n<code>''<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.seek(0) \u2464<\/code><br \/>\n<code>0<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read(10) \u2465<\/code><br \/>\n<code>'PapayaWhip'<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.tell()<\/code><br \/>\n<code>10<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.seek(18)<\/code><br \/>\n<code>18<\/code><br \/>\n<code>&gt;&gt;&gt; a_file.read()<\/code><br \/>\n<code>'new black.'<\/code><\/p>\n<ol>\n<li><code>io<\/code>\u6a21\u5757\u5b9a\u4e49\u4e86<code>StringIO<\/code>\u7c7b\uff0c\u5b83\u53ef\u4ee5\u8ba9\u4f60\u50cf\u5904\u7406\u6587\u4ef6\u4e00\u6837\u5904\u7406\u5185\u5b58\u4e2d\u7684\u5b57\u7b26\u4e32\u3002<\/li>\n<li>\u6839\u636e\u5b57\u7b26\u4e32\u521b\u5efa\u4e00\u4e2a\u6d41\u5bf9\u8c61\uff1b\u6839\u636e\u5b57\u7b26\u4e32\u521b\u5efa\u4e86\u4e00\u4e2aio.StringIO()\u5b9e\u4f8b\uff0c\u5e76\u628a\u5b57\u7b26\u4e32\u505a\u4e3a\u201c\u6587\u4ef6\u201d\u7684\u6570\u636e\u3002\u4e4b\u540e\u4f60\u5c31\u53ef\u4ee5\u50cf\u5176\u5b83\u6d41\u5bf9\u8c61\u4e00\u6837\u5bf9\u5b83\u8fdb\u884c\u64cd\u4f5c\u4e86\u3002<\/li>\n<li>\u8c03\u7528read()\u65b9\u6cd5\uff0c\u8bfb\u51fa\u5168\u90e8\u5185\u5bb9\uff0c\u5728StringIO\u5bf9\u8c61\u7684\u4f8b\u5b50\u4e2d\uff0c\u7b80\u5355\u7684\u8fd4\u56de\u539f\u59cb\u5b57\u7b26\u4e32\u3002<\/li>\n<li>\u5c31\u548c\u8bfb\u53d6\u771f\u5b9e\u6587\u4ef6\u4e00\u6837\uff0c\u5f53\u6ca1\u6709\u5b57\u7b26\u53ef\u8bfb\u4e86\uff0c\u5c31\u8fd4\u56de\u7a7a\u4e32\u3002<\/li>\n<li>\u53ef\u4ee5\u4f7f\u7528seek()\u51fd\u6570\uff0c\u5c31\u50cf\u5728\u771f\u5b9e\u6587\u4ef6\u4e0a\u7684\u7528\u6cd5\u4e00\u6837\u3002<\/li>\n<li>\u540c\u6837\u53ef\u4ee5\u4e00\u6b21\u8bfb\u53d6\u4e00\u5927\u5757\u6570\u636e\uff0c\u901a\u8fc7read()\u51fd\u6570\u7684size\u53c2\u6570\u3002<\/li>\n<\/ol>\n<p><em>io.StringIO\u8ba9\u4f60\u5904\u7406\u5b57\u7b26\u4e32\u65f6\u50cf\u662f\u5bf9\u5f85\u6587\u672c\u6587\u4ef6\u4e00\u6837\u3002\u540c\u6837io.BytesIO\u7c7b\u4e5f\u4f1a\u8ba9\u4f60\u5904\u7406\u5b57\u8282\u6570\u7ec4\u50cf\u662f\u4e8c\u8fdb\u5236\u6587\u4ef6\u4e00\u6837\u3002<\/em><\/p>\n<p>\uff0812\uff09\u5904\u7406\u538b\u7f29\u6587\u4ef6<\/p>\n<p>python\u6807\u51c6\u5e93\u5305\u542b\u4e86\u8bfb\u5199\u538b\u7f29\u6587\u4ef6\u7684\u6a21\u5757\u3002<\/p>\n<p>gzip\u6a21\u5757\u5141\u8bb8\u4f60\u521b\u5efa\u4e00\u4e2a\u7528\u4e8e\u8bfb\u5199gzip\u538b\u7f29\u6587\u4ef6\u7684\u6d41\u5bf9\u8c61\u3002\u4e4b\u540e\u5c31\u53ef\u4ee5\u50cf\u64cd\u4f5c\u6587\u672c\u6587\u4ef6\u4e00\u6837\u7528read()\u548cwrite()\u8fdb\u884c\u8bfb\u5199\uff0c\u800c\u4e0d\u7528\u4ea7\u751f\u4e34\u65f6\u6587\u4ef6\u3002gzip\u6d41\u5bf9\u8c61\u53ef\u4ee5\u4f7f\u7528with\u8bed\u53e5\u3002<\/p>\n<p><code> &gt;&gt;&gt; import gzip<\/code><br \/>\n<code>&gt;&gt;&gt; with gzip.open('out.log.gz', mode='wb') as z_file: \u2460<\/code><br \/>\n<code>...\u00a0\u00a0\u00a0\u00a0 z_file.write('A nine mile walk is no joke, especially in the rain.'.encode('utf-8'))<\/code><br \/>\n<code>...<\/code><br \/>\n<code>&gt;&gt;&gt; exit()<\/code><br \/>\n<code>you@localhost:~$ ls -l out.log.gz \u2461<\/code><br \/>\n<code>-rw-r--r-- 1 mark mark 79 2009-07-19 14:29 out.log.gz<\/code><br \/>\n<code>you@localhost:~$ gunzip out.log.gz \u2462<\/code><br \/>\n<code>you@localhost:~$ cat out.log \u2463<\/code><br \/>\n<code>A nine mile walk is no joke, especially in the rain.<\/code><\/p>\n<ol>\n<li>\u6253\u5f00\u4e00\u4e2agzip\u6587\u4ef6\uff0c\u5e94\u8be5\u4e00\u76f4\u4ee5\u4e8c\u8fdb\u5236\u65b9\u5f0f\u6253\u5f00\uff0cmode=&#8217;b&#8217;<\/li>\n<li>\u6587\u4ef6\u5927\u5c0f\u4e3a79\u4e2a\u5b57\u8282\uff0c\u4f46\u5b9e\u9645\u4e0a\u8fd9\u8981\u6bd4\u6211\u4eec\u5199\u5165\u7684\u5b57\u7b26\u957f\u5f88\u591a\u3002\u8fd9\u662f\u56e0\u4e3agzip\u683c\u5f0f\u5305\u542b\u4e86\u56fa\u5b9a\u957f\u5ea6\u7684\u5934\u6587\u4ef6\uff0c\u5b83\u5305\u542b\u4e86\u4e00\u4e9b\u5173\u4e8e\u6587\u4ef6\u7684meta\u6570\u636e\uff0c\u6240\u4ee5\u7528gzip\u683c\u5f0f\u6253\u5305\u7279\u522b\u5c0f\u7684\u6587\u4ef6\u65f6\uff0c\u6548\u7387\u5f88\u4f4e\u3002<\/li>\n<li>gunzip\u547d\u4ee4\u53ef\u4ee5\u89e3\u538b\u4e00\u4e2agzip\u6587\u4ef6\uff0c\u540d\u5b50\u548c\u539f\u6587\u4ef6\u4e00\u6837\u53ea\u4e0d\u8fc7\u6ca1\u6709gz\u6269\u5c55\u540d\u3002<\/li>\n<li>cat\u547d\u4ee4\u663e\u793a\u6587\u4ef6\u5185\u5bb9\u3002<\/li>\n<\/ol>\n<p>\uff0813\uff09\u6807\u51c6\u8f93\u51fa\u548c\u9519\u8bef<\/p>\n<p>sys.stdout\u548csys.stderr\u90fd\u662f\u6d41\u5bf9\u8c61\uff0c\u4e0d\u8fc7\u5b83\u4eec\u662f\u53ea\u5199\u7684\uff0c\u5bf9\u4ed6\u4eec\u4f7f\u7528read()\u65b9\u6cd5\u4f1a\u5f15\u53d1\u5f02\u5e38\u3002<\/p>\n<h2>\uff0814\uff09\u91cd\u5b9a\u5411\u6807\u51c6\u8f93\u51fa<\/h2>\n<p>sys.stdout\u548csys.stderr\u90fd\u662f\u6d41\u5bf9\u8c61\uff0c\u4f46\u662f\u53ea\u652f\u6301\u5199\u64cd\u4f5c\u3002\u5982\u679c\u5bf9\u5b83\u4eec\u8d4b\u4e88\u4e00\u4e2a\u65b0\u503c\u2014\u2014\u53e6\u4e00\u4e2a\u6d41\u5bf9\u8c61\u2014\u2014\u5c31\u662f\u91cd\u5b9a\u5411\u4ed6\u4eec\u5230\u8f93\u51fa\u3002<\/p>\n<p><code> import sys<\/code><br \/>\n<code>class RedirectStdoutTo:<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 def __init__(self, out_new):<\/code><br \/>\n<code>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 self.out_new = out_new<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 def __enter__(self):<\/code><br \/>\n<code>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 self.out_old = sys.stdout<\/code><br \/>\n<code>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 sys.stdout = self.out_new<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 def __exit__(self, *args):<\/code><br \/>\n<code>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 sys.stdout = self.out_old<\/code><br \/>\n<code>print('A')<\/code><br \/>\n<code>with open('out.log', mode='w', encoding='utf-8') as a_file, RedirectStdoutTo(a_file):<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 print('B')<\/code><br \/>\n<code>print('C')<\/code><\/p>\n<p>\u68c0\u67e5\u8f93\u51fa:<br \/>\nyou@localhost:~\/diveintopython3\/examples$ python3 stdout.py<br \/>\nA C<br \/>\nyou@localhost:~\/diveintopython3\/examples$ cat out.log<br \/>\nB<\/p>\n<p><strong>\u8ba9\u6211\u4eec\u5148\u770b\u4e00\u4e0b\u6700\u540e\u4e00\u90e8\u5206<\/strong>\uff1a<\/p>\n<p><code> print('A')<\/code><br \/>\n<code>with open('out.log', mode='w', encoding='utf-8') as a_file, RedirectStdoutTo(a_file):<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 print('B')<\/code><br \/>\n<code>print('C')<\/code><\/p>\n<p>\u5c06\u8fd9\u4e2a\u590d\u6742\u7684with\u8bed\u53e5\u91cd\u5199\u6210\u66f4\u5bb9\u6613\u7406\u7406\u89e3\u7684\u65b9\u5f0f\uff1a<\/p>\n<p><code> with open('out.log', mode='w', encoding='utf-8') as a_file:<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 with RedirectStdoutTo(a_file):<\/code><br \/>\n<code>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 print('B')<\/code><\/p>\n<p>\u6b63\u5982\u91cd\u5199\u7684\u90a3\u6837\uff0c\u5b9e\u9645\u4e0a\u6709\u4e24\u4e2awith\u8bed\u53e5\uff0c\u4e00\u4e2a\u5d4c\u5957\u5230\u53e6\u4e00\u4e2a\u91cc\u9762\u3002\u5916\u5c42\u7684with\u8bed\u53e5\u6211\u4eec\u5e94\u8be5\u6bd4\u8f83\u719f\u6089\u4e86\uff1a\u5b83\u4ee5UTF-8\u7f16\u7801\u65b9\u5f0f\u6253\u5f00\u4e86\u4e00\u4e2a\u540d\u4e3aout.log\u6587\u4ef6\uff0c\u6253\u5f00\u6a21\u5f0f\u4e3a\u201c\u5199\u201d\u6a21\u5f0f\uff0c\u5e76\u5206\u914d\u4e86\u4e00\u4e2a\u540d\u4e3aa_file\u7684\u6d41\u5bf9\u8c61\u7ed9\u5b83\u3002\u4f46\u8fd9\u8fd8\u6ca1\u5b8c\u3002\u3002\u3002<\/p>\n<p><code>\u00a0\u00a0\u00a0 <strong>with RedirectStdoutTo(a_file):<\/strong><\/code><\/p>\n<p>\u8fd9\u53e5\u6ca1\u6709as\u5206\u652f\uff01\u5b9e\u9645\u4e0awith\u8bed\u53e5\u5e76\u4e0d\u9700\u8981\u5b83\u3002\u5c31\u50cf\u8c03\u7528\u4e00\u4e2a\u7a0b\u5e8f\u5e76\u5ffd\u7565\u5b83\u7684\u8fd4\u56de\u503c\uff0c\u800c\u5728with\u8bed\u53e5\u4e2d\u53ef\u4ee5\u4e0d\u5206\u914d\u201c\u4e0a\u4e0b\u6587\u201d\u5230\u4e00\u4e2a\u53d8\u91cf\u4e0a\u3002\u5728\u672c\u4f8b\u4e2d\u53ea\u5bf9<code>RedirectStoutTo<\/code>\u201c\u4e0a\u4e0b\u6587\u201d\u7684\u526f\u4f5c\u7528\uff08side effect\uff09\u611f\u5174\u8da3\u3002<\/p>\n<p>\u5b83\u7684\u526f\u4f5c\u7528\u662f\u4ec0\u4e48\u5462\uff1f\u8ba9\u6211\u4eec\u770b\u4e00\u4e0b<code>RedirectStdoutTo<\/code>\u7c7b\u3002\u8fd9\u4e2a\u7c7b\u662f\u4e00\u4e2a\u201c\u4e0a\u4e0b\u6587\u7ba1\u7406\u5668\u201d\u3002\u53ea\u8981\u5b9a\u4e49\u4e86__enter__()\u548c__exit__()\u8fd9\u4e24\u4e2a\u65b9\u6cd5\u7684\u7c7b\uff0c\u90fd\u53ef\u4ee5\u505a\u4e3a\u201c\u4e0a\u4e0b\u6587\u7ba1\u7406\u5668\u201d\u3002<\/p>\n<p><code> class RedirectStdoutTo:<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 def __init__(self, out_new):\u00a0\u00a0\u00a0\u00a0 \u2460<\/code><br \/>\n<code>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 self.out_new = out_new<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 def __enter__(self):\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u2461<\/code><br \/>\n<code>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 self.out_old = sys.stdout<\/code><br \/>\n<code>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 sys.stdout = self.out_new<\/code><br \/>\n<code>\u00a0\u00a0\u00a0 def __exit__(self, *args):\u00a0\u00a0\u00a0\u00a0\u00a0 \u2462<\/code><br \/>\n<code>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 sys.stdout = self.out_old<\/code><\/p>\n<ol>\n<li>__init__()\u65b9\u6cd5\u5728\u5b9e\u4f8b\u5efa\u7acb\u540e\u7acb\u5373\u6267\u884c\u3002\u672c\u4f8b\u4e2d\u5b83\u4f7f\u7528\u4e00\u4e2a\u6d41\u5bf9\u8c61\u53c2\u6570\uff0c\u4f60\u60f3\u4f7f\u7528\u5b83\u505a\u4e3a\u201c\u4e0a\u4e0b\u6587\u201d\u751f\u5b58\u671f\u7684\u6807\u51c6\u8f93\u51fa\u3002\u8fd9\u4e2a\u65b9\u6cd5\u4ec5\u5728\u4f8b\u4e2d\u4fdd\u5b58\u4e86\u6d41\u5bf9\u8c61\uff0c\u7528\u4e8e\u5176\u5b83\u65b9\u6cd5\u4ee5\u540e\u4f7f\u7528\u5b83\u3002<\/li>\n<li>__enter__()\u65b9\u6cd5\u662f\u4e00\u4e2a\u7279\u6b8a\u7684\u7c7b\u65b9\u6cd5\u3002\u5f53\u8fdb\u5165\u201c\u4e0a\u4e0b\u6587\u201d\u65f6\u6267\u884c\uff08\u4e5f\u5c31\u662f\u5728\u5f00\u59cbwith\u8bed\u53e5\u65f6\uff09\u3002\u672c\u4f8b\u4e2d\u8fd9\u4e2a\u65b9\u6cd5\u4fdd\u5b58\u4e86\u5f53\u524dsys.stdout\u7684\u503c\u5728self.out_old\u4e2d\uff0c\u4e4b\u540e\u901a\u8fc7self.out_new\u8d4b\u7ed9sys.stdout\u91cd\u5b9a\u5411\u4e86\u6807\u51c6\u8f93\u51fa\u3002<\/li>\n<li>__exit__()\u65b9\u6cd5\u662f\u53e6\u4e00\u4e2a\u7279\u6b8a\u7684\u7c7b\u65b9\u6cd5\u3002\u5f53\u79bb\u5f00\u201c\u4e0a\u4e0b\u6587\u201d\u65f6\u6267\u884c\uff08\u4e5f\u5c31\u662f\u5728\u7ed3\u675fwith\u8bed\u53e5\u65f6\uff09\u3002\u5728\u672c\u4f8b\u4e2d\u8fd9\u4e2a\u65b9\u6cd5\u901a\u8fc7\u628a\u4e4b\u524d\u4fdd\u5b58\u7684self.out_old\u503c\u8d4b\u7ed9sys.stdout\u6765\u6062\u590d\u6807\u51c6\u8f93\u51fa\u5230\u539f\u6765\u7684\u503c\u3002<\/li>\n<\/ol>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\uff081\uff09\u5728pythonk \u4e2d\u6253\u5f00\u6587\u4ef6\u975e\u5e38\u7684\u7b80\u5355\uff1a a_file = open(&#8216;examples\/chinese.txt&#8217;, encodi&#8230;<\/p>\n<p class=\"read-more\"><a class=\"btn btn-default\" href=\"https:\/\/www.5x44.cn\/?p=179\"> Read More<span class=\"screen-reader-text\">  Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-179","post","type-post","status-publish","format-standard","hentry","category-dive-into-python3"],"_links":{"self":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/179","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=179"}],"version-history":[{"count":9,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/179\/revisions"}],"predecessor-version":[{"id":194,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/179\/revisions\/194"}],"wp:attachment":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=179"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=179"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=179"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}