{"id":145,"date":"2026-05-10T11:12:45","date_gmt":"2026-05-10T03:12:45","guid":{"rendered":"https:\/\/www.xzqbear.com\/?p=145"},"modified":"2026-05-10T11:14:08","modified_gmt":"2026-05-10T03:14:08","slug":"python-%e8%ae%be%e8%ae%a1%e6%a8%a1%e5%bc%8f-%e5%8d%95%e4%be%8b%e6%a8%a1%e5%bc%8f","status":"publish","type":"post","link":"https:\/\/www.xzqbear.com\/index.php\/2026\/05\/10\/python-%e8%ae%be%e8%ae%a1%e6%a8%a1%e5%bc%8f-%e5%8d%95%e4%be%8b%e6%a8%a1%e5%bc%8f\/","title":{"rendered":"Python \u8bbe\u8ba1\u6a21\u5f0f \u2014\u2014 \u5355\u4f8b\u6a21\u5f0f"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">\u5355\u4f8b\u6a21\u5f0f\u7684\u6982\u5ff5<\/h2>\n\n\n\n<p>\u5355\u4f8b\u6a21\u5f0f\u662f\u4e00\u79cd\u5e38\u7528\u7684\u8f6f\u4ef6<a href=\"https:\/\/www.runoob.com\/design-pattern\/design-pattern-tutorial.html\" target=\"_blank\" rel=\"noreferrer noopener\">\u8bbe\u8ba1\u6a21\u5f0f<\/a>\uff0c\u5b83\u786e\u4fdd\u4e00\u4e2a\u7c7b\u53ea\u6709\u4e00\u4e2a\u5b9e\u4f8b\uff0c\u5e76\u63d0\u4f9b\u4e00\u4e2a\u5168\u5c40\u8bbf\u95ee\u70b9\u6765\u83b7\u53d6\u8fd9\u4e2a\u5b9e\u4f8b.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u6838\u5fc3\u6982\u5ff5<\/h3>\n\n\n\n<p>\u60f3\u8c61\u4e00\u4e0b\u516c\u53f8\u7684 CEO \u804c\u4f4d &#8211; \u6574\u4e2a\u516c\u53f8\u53ea\u80fd\u6709\u4e00\u4e2a CEO\uff0c\u65e0\u8bba\u54ea\u4e2a\u90e8\u95e8\u9700\u8981\u5411 CEO \u6c47\u62a5\uff0c\u4ed6\u4eec\u8bbf\u95ee\u7684\u90fd\u662f\u540c\u4e00\u4e2a CEO \u5bf9\u8c61\u3002\u5355\u4f8b\u6a21\u5f0f\u5c31\u662f\u7f16\u7a0b\u4e16\u754c\u4e2d\u7684&#8221;CEO \u804c\u4f4d\u7ba1\u7406\u673a\u5236&#8221;.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u4e3a\u4ec0\u4e48\u9700\u8981\u5355\u4f8b\u6a21\u5f0f<\/h3>\n\n\n\n<p>\u5728\u5b9e\u9645\u5f00\u53d1\u4e2d\uff0c\u6709\u4e9b\u5bf9\u8c61\u6211\u4eec\u53ea\u9700\u8981\u4e00\u4e2a\u5b9e\u4f8b\u5c31\u8db3\u591f\u4e86\uff0c\u6bd4\u5982\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u914d\u7f6e\u7ba1\u7406\u5668<\/strong>\uff1a\u6574\u4e2a\u5e94\u7528\u7a0b\u5e8f\u5171\u4eab\u540c\u4e00\u5957\u914d\u7f6e<\/li>\n\n\n\n<li><strong>\u6570\u636e\u5e93\u8fde\u63a5\u6c60<\/strong>\uff1a\u907f\u514d\u91cd\u590d\u521b\u5efa\u8fde\u63a5\uff0c\u8282\u7701\u8d44\u6e90<\/li>\n\n\n\n<li><strong>\u65e5\u5fd7\u8bb0\u5f55\u5668<\/strong>\uff1a\u786e\u4fdd\u6240\u6709\u65e5\u5fd7\u90fd\u5199\u5165\u540c\u4e00\u4e2a\u6587\u4ef6<\/li>\n\n\n\n<li><strong>\u7f13\u5b58\u7cfb\u7edf<\/strong>\uff1a\u7edf\u4e00\u7ba1\u7406\u7f13\u5b58\u6570\u636e<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Python \u5177\u4f53\u5b9e\u73b0\u65b9\u6cd5<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u6a21\u5757<\/h3>\n\n\n\n<p>Python \u7684\u6a21\u5757\u9ed8\u8ba4\u91c7\u7528\u5355\u4f8b\u6a21\u5f0f\uff0c\u4e5f\u5c31\u662f\u53ea\u521d\u59cb\u5316\u4e00\u6b21\uff0c\u591a\u6b21 <code>import<\/code> \u5e76\u4e0d\u4f1a\u591a\u6b21\u5bfc\u5165. \u4f8b\u5982\uff1a<\/p>\n\n\n\n<div class=\"wp-block-kevinbatdorf-code-block-pro cbp-has-line-numbers\" data-code-block-pro-font-family=\"Code-Pro-JetBrains-Mono\" style=\"font-size:.875rem;font-family:Code-Pro-JetBrains-Mono,ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;--cbp-line-number-color:#e1e4e8;--cbp-line-number-width:calc(2 * 0.6 * .875rem);line-height:1.25rem;--cbp-tab-width:2;tab-size:var(--cbp-tab-width, 2)\"><span style=\"display:flex;align-items:center;padding:10px 0px 10px 16px;margin-bottom:-2px;width:100%;text-align:left;background-color:#2f363c;color:#d3d7dd\">Python<\/span><span role=\"button\" tabindex=\"0\" style=\"color:#e1e4e8;display:none\" aria-label=\"\u590d\u5236\" class=\"code-block-pro-copy-button\"><pre class=\"code-block-pro-copy-button-pre\" aria-hidden=\"true\"><textarea class=\"code-block-pro-copy-button-textarea\" tabindex=\"-1\" aria-hidden=\"true\" readonly># \u5355\u4f8b\u6a21\u5f0f\u7684\u5b9e\u73b0\u65b9\u5f0f\uff1a\u5bfc\u5165\u6a21\u5757\n# \u6570\u636e\u5e93\u4f8b\u5b50\nclass DatabaseConnection:\n    def __init__(self):\n        self.connection_string = \"database:\/\/localhost:5432\/mydb\"\n        print(\"\u6570\u636e\u5e93\u8fde\u63a5\u5df2\u521b\u5efa\")\n\n    def query(self, sql):\n        return f\"\u6267\u884c\u67e5\u8be2: {sql}\"\n\n# \u521b\u5efa\u5355\u4f8b\u5b9e\u4f8b\ndb_instance = DatabaseConnection()\n<\/textarea><\/pre><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"width:24px;height:24px\" fill=\"none\" viewBox=\"0 0 24 24\" stroke=\"currentColor\" stroke-width=\"2\"><path class=\"with-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2m-6 9l2 2 4-4\"><\/path><path class=\"without-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2\"><\/path><\/svg><\/span><pre class=\"shiki github-dark\" style=\"background-color: #24292e\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color: #6A737D\"># \u5355\u4f8b\u6a21\u5f0f\u7684\u5b9e\u73b0\u65b9\u5f0f\uff1a\u5bfc\u5165\u6a21\u5757<\/span><\/span>\n<span class=\"line\"><span style=\"color: #6A737D\"># \u6570\u636e\u5e93\u4f8b\u5b50<\/span><\/span>\n<span class=\"line\"><span style=\"color: #F97583\">class<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #B392F0\">DatabaseConnection<\/span><span style=\"color: #E1E4E8\">:<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #F97583\">def<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">__init__<\/span><span style=\"color: #E1E4E8\">(self):<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #79B8FF\">self<\/span><span style=\"color: #E1E4E8\">.connection_string <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #9ECBFF\">&quot;database:\/\/localhost:5432\/mydb&quot;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #79B8FF\">print<\/span><span style=\"color: #E1E4E8\">(<\/span><span style=\"color: #9ECBFF\">&quot;\u6570\u636e\u5e93\u8fde\u63a5\u5df2\u521b\u5efa&quot;<\/span><span style=\"color: #E1E4E8\">)<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #F97583\">def<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #B392F0\">query<\/span><span style=\"color: #E1E4E8\">(self, sql):<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #F97583\">return<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #F97583\">f<\/span><span style=\"color: #9ECBFF\">&quot;\u6267\u884c\u67e5\u8be2: <\/span><span style=\"color: #79B8FF\">{<\/span><span style=\"color: #E1E4E8\">sql<\/span><span style=\"color: #79B8FF\">}<\/span><span style=\"color: #9ECBFF\">&quot;<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #6A737D\"># \u521b\u5efa\u5355\u4f8b\u5b9e\u4f8b<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">db_instance <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> DatabaseConnection()<\/span><\/span>\n<span class=\"line\"><\/span><\/code><\/pre><\/div>\n\n\n\n<p>\u6b64\u65f6\u5728\u53e6\u4e00\u4e2a\u6587\u4ef6\u5bfc\u5165\uff1a<\/p>\n\n\n\n<div class=\"wp-block-kevinbatdorf-code-block-pro cbp-has-line-numbers\" data-code-block-pro-font-family=\"Code-Pro-JetBrains-Mono\" style=\"font-size:.875rem;font-family:Code-Pro-JetBrains-Mono,ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;--cbp-line-number-color:#e1e4e8;--cbp-line-number-width:calc(1 * 0.6 * .875rem);line-height:1.25rem;--cbp-tab-width:2;tab-size:var(--cbp-tab-width, 2)\"><span style=\"display:flex;align-items:center;padding:10px 0px 10px 16px;margin-bottom:-2px;width:100%;text-align:left;background-color:#2f363c;color:#d3d7dd\">Python<\/span><span role=\"button\" tabindex=\"0\" style=\"color:#e1e4e8;display:none\" aria-label=\"\u590d\u5236\" class=\"code-block-pro-copy-button\"><pre class=\"code-block-pro-copy-button-pre\" aria-hidden=\"true\"><textarea class=\"code-block-pro-copy-button-textarea\" tabindex=\"-1\" aria-hidden=\"true\" readonly>from singleton_module import db_instance\n\n# \u53ea\u66b4\u9732 db_instance \u63a5\u53e3\uff0c\u4fdd\u8bc1\u5355\u4f8b\n\nprint(db_instance.query(\"SELECT * FROM data;\"))\n<\/textarea><\/pre><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"width:24px;height:24px\" fill=\"none\" viewBox=\"0 0 24 24\" stroke=\"currentColor\" stroke-width=\"2\"><path class=\"with-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2m-6 9l2 2 4-4\"><\/path><path class=\"without-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2\"><\/path><\/svg><\/span><pre class=\"shiki github-dark\" style=\"background-color: #24292e\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color: #F97583\">from<\/span><span style=\"color: #E1E4E8\"> singleton_module <\/span><span style=\"color: #F97583\">import<\/span><span style=\"color: #E1E4E8\"> db_instance<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #6A737D\"># \u53ea\u66b4\u9732 db_instance \u63a5\u53e3\uff0c\u4fdd\u8bc1\u5355\u4f8b<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #79B8FF\">print<\/span><span style=\"color: #E1E4E8\">(db_instance.query(<\/span><span style=\"color: #9ECBFF\">&quot;SELECT * FROM data;&quot;<\/span><span style=\"color: #E1E4E8\">))<\/span><\/span>\n<span class=\"line\"><\/span><\/code><\/pre><\/div>\n\n\n\n<p>\u6b64\u65f6 <code>db_instance<\/code> \u662f\u552f\u4e00\u7684\u5355\u4f8b\uff0c\u63a5\u53e3\u53ea\u66b4\u9732\u5b83\u7684\u8bdd\u5c31\u5b9e\u73b0\u4e86\u5355\u4f8b\u6a21\u5f0f.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u9b54\u6cd5\u65b9\u6cd5 <code>__new__<\/code><\/h3>\n\n\n\n<p>\u8fd9\u91cc\u4e3a <code>class<\/code> \u65b0\u589e\u4e00\u4e2a <code>_instance<\/code> \uff08\u4ec0\u4e48\u540d\u5b57\u90fd\u884c\uff09\uff0c\u7528\u4e8e\u7f13\u5b58\u771f\u6b63\u7684\u5355\u4f8b\uff0c\u7b2c\u4e00\u6b21\u521d\u59cb\u5316\u5c31\u8d1f\u8d23\u521b\u5efa\u5e76\u5b58\u653e\u5355\u4f8b\uff0c\u540e\u9762\u7684\u521d\u59cb\u5316\u90fd\u53ea\u8fd4\u56de\u7f13\u5b58\u5373\u53ef\uff1a<\/p>\n\n\n\n<div class=\"wp-block-kevinbatdorf-code-block-pro cbp-has-line-numbers\" data-code-block-pro-font-family=\"Code-Pro-JetBrains-Mono\" style=\"font-size:.875rem;font-family:Code-Pro-JetBrains-Mono,ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;--cbp-line-number-color:#e1e4e8;--cbp-line-number-width:calc(2 * 0.6 * .875rem);line-height:1.25rem;--cbp-tab-width:2;tab-size:var(--cbp-tab-width, 2)\"><span style=\"display:flex;align-items:center;padding:10px 0px 10px 16px;margin-bottom:-2px;width:100%;text-align:left;background-color:#2f363c;color:#d3d7dd\">Python<\/span><span role=\"button\" tabindex=\"0\" style=\"color:#e1e4e8;display:none\" aria-label=\"\u590d\u5236\" class=\"code-block-pro-copy-button\"><pre class=\"code-block-pro-copy-button-pre\" aria-hidden=\"true\"><textarea class=\"code-block-pro-copy-button-textarea\" tabindex=\"-1\" aria-hidden=\"true\" readonly>class DatabaseConnection:\n    _instance = None\n\n    def __init__(self):\n        self.connection_string = \"database:\/\/localhost:5432\/mydb\"\n        print(\"\u6570\u636e\u5e93\u8fde\u63a5\u5df2\u521b\u5efa\")\n\n    def __new__(cls, *args, **kwargs):\n        if not cls._instance:\n            cls._instance = super().__new__(cls)\n            print(\"\u521b\u5efa\u65b0\u5b9e\u4f8b\")\n        else:\n            print(\"\u8fd4\u56de\u5df2\u6709\u5b9e\u4f8b\")\n\n        return cls._instance\n\n    def query(self, sql):\n        return f\"\u6267\u884c\u67e5\u8be2: {sql}\"\n\n\ndb1 = DatabaseConnection()\ndb2 = DatabaseConnection()\n\nprint(db1 is db2)\n<\/textarea><\/pre><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"width:24px;height:24px\" fill=\"none\" viewBox=\"0 0 24 24\" stroke=\"currentColor\" stroke-width=\"2\"><path class=\"with-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2m-6 9l2 2 4-4\"><\/path><path class=\"without-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2\"><\/path><\/svg><\/span><pre class=\"shiki github-dark\" style=\"background-color: #24292e\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color: #F97583\">class<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #B392F0\">DatabaseConnection<\/span><span style=\"color: #E1E4E8\">:<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    _instance <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">None<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #F97583\">def<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">__init__<\/span><span style=\"color: #E1E4E8\">(self):<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #79B8FF\">self<\/span><span style=\"color: #E1E4E8\">.connection_string <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #9ECBFF\">&quot;database:\/\/localhost:5432\/mydb&quot;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #79B8FF\">print<\/span><span style=\"color: #E1E4E8\">(<\/span><span style=\"color: #9ECBFF\">&quot;\u6570\u636e\u5e93\u8fde\u63a5\u5df2\u521b\u5efa&quot;<\/span><span style=\"color: #E1E4E8\">)<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #F97583\">def<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">__new__<\/span><span style=\"color: #E1E4E8\">(cls, <\/span><span style=\"color: #F97583\">*<\/span><span style=\"color: #E1E4E8\">args, <\/span><span style=\"color: #F97583\">**<\/span><span style=\"color: #E1E4E8\">kwargs):<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #F97583\">if<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #F97583\">not<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">cls<\/span><span style=\"color: #E1E4E8\">._instance:<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">            <\/span><span style=\"color: #79B8FF\">cls<\/span><span style=\"color: #E1E4E8\">._instance <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">super<\/span><span style=\"color: #E1E4E8\">().<\/span><span style=\"color: #79B8FF\">__new__<\/span><span style=\"color: #E1E4E8\">(<\/span><span style=\"color: #79B8FF\">cls<\/span><span style=\"color: #E1E4E8\">)<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">            <\/span><span style=\"color: #79B8FF\">print<\/span><span style=\"color: #E1E4E8\">(<\/span><span style=\"color: #9ECBFF\">&quot;\u521b\u5efa\u65b0\u5b9e\u4f8b&quot;<\/span><span style=\"color: #E1E4E8\">)<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #F97583\">else<\/span><span style=\"color: #E1E4E8\">:<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">            <\/span><span style=\"color: #79B8FF\">print<\/span><span style=\"color: #E1E4E8\">(<\/span><span style=\"color: #9ECBFF\">&quot;\u8fd4\u56de\u5df2\u6709\u5b9e\u4f8b&quot;<\/span><span style=\"color: #E1E4E8\">)<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #F97583\">return<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">cls<\/span><span style=\"color: #E1E4E8\">._instance<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #F97583\">def<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #B392F0\">query<\/span><span style=\"color: #E1E4E8\">(self, sql):<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #F97583\">return<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #F97583\">f<\/span><span style=\"color: #9ECBFF\">&quot;\u6267\u884c\u67e5\u8be2: <\/span><span style=\"color: #79B8FF\">{<\/span><span style=\"color: #E1E4E8\">sql<\/span><span style=\"color: #79B8FF\">}<\/span><span style=\"color: #9ECBFF\">&quot;<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">db1 <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> DatabaseConnection()<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">db2 <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> DatabaseConnection()<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #79B8FF\">print<\/span><span style=\"color: #E1E4E8\">(db1 <\/span><span style=\"color: #F97583\">is<\/span><span style=\"color: #E1E4E8\"> db2)<\/span><\/span>\n<span class=\"line\"><\/span><\/code><\/pre><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">\u88c5\u9970\u5668<\/h3>\n\n\n\n<p>\u4f7f\u7528 Python \u7684\u88c5\u9970\u5668\u53ef\u4ee5\u975e\u5e38\u7b80\u6d01\u5730\u5b9e\u73b0\uff0c\u5e76\u4e14\u53ef\u590d\u7528\uff0c\u66f4\u63a8\u8350\u8fd9\u79cd\u505a\u6cd5\uff0c\u65b9\u4fbf\u89e3\u8026.<\/p>\n\n\n\n<div class=\"wp-block-kevinbatdorf-code-block-pro cbp-has-line-numbers\" data-code-block-pro-font-family=\"Code-Pro-JetBrains-Mono\" style=\"font-size:.875rem;font-family:Code-Pro-JetBrains-Mono,ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;--cbp-line-number-color:#e1e4e8;--cbp-line-number-width:calc(2 * 0.6 * .875rem);line-height:1.25rem;--cbp-tab-width:2;tab-size:var(--cbp-tab-width, 2)\"><span style=\"display:flex;align-items:center;padding:10px 0px 10px 16px;margin-bottom:-2px;width:100%;text-align:left;background-color:#2f363c;color:#d3d7dd\">Python<\/span><span role=\"button\" tabindex=\"0\" style=\"color:#e1e4e8;display:none\" aria-label=\"\u590d\u5236\" class=\"code-block-pro-copy-button\"><pre class=\"code-block-pro-copy-button-pre\" aria-hidden=\"true\"><textarea class=\"code-block-pro-copy-button-textarea\" tabindex=\"-1\" aria-hidden=\"true\" readonly>def singleton(cls):\n    \"\"\"\u5355\u4f8b\u88c5\u9970\u5668\"\"\"\n    instances = {}\n\n    def wrapper(*args, **kwargs):\n        if cls not in instances:\n            instances&#91;cls&#93; = cls(*args, **kwargs)\n\n        return instances&#91;cls&#93;\n\n    return wrapper\n\n\n@singleton\nclass DatabaseConnection:\n    _instance = None\n\n    def __init__(self):\n        self.connection_string = \"database:\/\/localhost:5432\/mydb\"\n        print(\"\u6570\u636e\u5e93\u8fde\u63a5\u5df2\u521b\u5efa\")\n\n    def query(self, sql):\n        return f\"\u6267\u884c\u67e5\u8be2: {sql}\"\n\n\ndb1 = DatabaseConnection()\ndb2 = DatabaseConnection()\n\nprint(db1 is db2)\n<\/textarea><\/pre><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"width:24px;height:24px\" fill=\"none\" viewBox=\"0 0 24 24\" stroke=\"currentColor\" stroke-width=\"2\"><path class=\"with-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2m-6 9l2 2 4-4\"><\/path><path class=\"without-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2\"><\/path><\/svg><\/span><pre class=\"shiki github-dark\" style=\"background-color: #24292e\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color: #F97583\">def<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #B392F0\">singleton<\/span><span style=\"color: #E1E4E8\">(cls):<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #9ECBFF\">&quot;&quot;&quot;\u5355\u4f8b\u88c5\u9970\u5668&quot;&quot;&quot;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    instances <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> {}<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #F97583\">def<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #B392F0\">wrapper<\/span><span style=\"color: #E1E4E8\">(<\/span><span style=\"color: #F97583\">*<\/span><span style=\"color: #E1E4E8\">args, <\/span><span style=\"color: #F97583\">**<\/span><span style=\"color: #E1E4E8\">kwargs):<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #F97583\">if<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">cls<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #F97583\">not<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #F97583\">in<\/span><span style=\"color: #E1E4E8\"> instances:<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">            instances&#91;<\/span><span style=\"color: #79B8FF\">cls<\/span><span style=\"color: #E1E4E8\">&#93; <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">cls<\/span><span style=\"color: #E1E4E8\">(<\/span><span style=\"color: #F97583\">*<\/span><span style=\"color: #E1E4E8\">args, <\/span><span style=\"color: #F97583\">**<\/span><span style=\"color: #E1E4E8\">kwargs)<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #F97583\">return<\/span><span style=\"color: #E1E4E8\"> instances&#91;<\/span><span style=\"color: #79B8FF\">cls<\/span><span style=\"color: #E1E4E8\">&#93;<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #F97583\">return<\/span><span style=\"color: #E1E4E8\"> wrapper<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #B392F0\">@singleton<\/span><\/span>\n<span class=\"line\"><span style=\"color: #F97583\">class<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #B392F0\">DatabaseConnection<\/span><span style=\"color: #E1E4E8\">:<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    _instance <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">None<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #F97583\">def<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #79B8FF\">__init__<\/span><span style=\"color: #E1E4E8\">(self):<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #79B8FF\">self<\/span><span style=\"color: #E1E4E8\">.connection_string <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #9ECBFF\">&quot;database:\/\/localhost:5432\/mydb&quot;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #79B8FF\">print<\/span><span style=\"color: #E1E4E8\">(<\/span><span style=\"color: #9ECBFF\">&quot;\u6570\u636e\u5e93\u8fde\u63a5\u5df2\u521b\u5efa&quot;<\/span><span style=\"color: #E1E4E8\">)<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">    <\/span><span style=\"color: #F97583\">def<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #B392F0\">query<\/span><span style=\"color: #E1E4E8\">(self, sql):<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">        <\/span><span style=\"color: #F97583\">return<\/span><span style=\"color: #E1E4E8\"> <\/span><span style=\"color: #F97583\">f<\/span><span style=\"color: #9ECBFF\">&quot;\u6267\u884c\u67e5\u8be2: <\/span><span style=\"color: #79B8FF\">{<\/span><span style=\"color: #E1E4E8\">sql<\/span><span style=\"color: #79B8FF\">}<\/span><span style=\"color: #9ECBFF\">&quot;<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">db1 <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> DatabaseConnection()<\/span><\/span>\n<span class=\"line\"><span style=\"color: #E1E4E8\">db2 <\/span><span style=\"color: #F97583\">=<\/span><span style=\"color: #E1E4E8\"> DatabaseConnection()<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #79B8FF\">print<\/span><span style=\"color: #E1E4E8\">(db1 <\/span><span style=\"color: #F97583\">is<\/span><span style=\"color: #E1E4E8\"> db2)<\/span><\/span>\n<span class=\"line\"><\/span><\/code><\/pre><\/div>\n\n\n\n<p>\u8fd9\u91cc\u8fdb\u884c\u4e00\u4e0b\u89e3\u6790\uff0c\u88c5\u9970\u5668\u4e00\u822c\u901a\u8fc7\u8fd4\u56de\u4e00\u4e2a\u5185\u90e8\u51fd\u6570\uff0c\u8c03\u7528\u7684\u65f6\u5019\u5c31\u7c7b\u4f3c <code>DatabaseConnection = singleton(DatabaseConnection)<\/code> \uff0c\u539f\u7406\u8fd8\u662f\u548c <code>__new__<\/code> \u65b9\u6cd5\u4e00\u6837\uff0c\u521b\u5efa\u7f13\u5b58\u6765\u5b58\u653e\u5355\u4f8b.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u5355\u4f8b\u6a21\u5f0f\u7684\u7f3a\u9677<\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u9700\u8981\u5355\u5143\u6d4b\u8bd5\u7684\u65f6\u5019\uff0c\u65e0\u6cd5\u4f7f\u7528\u5355\u4f8b\u6a21\u5f0f\uff0c\u56e0\u4e3a\u6d4b\u8bd5\u4f1a\u66f4\u6539\u5355\u4f8b\u7684\u72b6\u6001\uff1b<\/li>\n\n\n\n<li>\u591a\u7ebf\u7a0b\u60c5\u51b5\u4e0b\uff0c\u7531\u4e8e\u4e24\u4e2a\u7ebf\u7a0b\u4e4b\u95f4\u540c\u65f6\u8c03\u7528 <code>__new__<\/code> \u7684\u65f6\u5019\uff0c\u53ef\u80fd\u540c\u65f6\u521b\u5efa\u4e24\u4e2a\u4e0d\u540c\u7684\u5b9e\u4f8b\uff0c\u4f1a\u7834\u574f\u5355\u4f8b\u6a21\u5f0f\uff0c\u56e0\u6b64\u9700\u8981\u52a0\u7ebf\u7a0b\u9501.<\/li>\n\n\n\n<li>\u9700\u8981\u591a\u6001\u7684\u65f6\u5019\u5e94\u8be5\u5c3d\u91cf\u907f\u514d\u5355\u4f8b\u6a21\u5f0f.<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>\u5355\u4f8b\u6a21\u5f0f\u7684\u6982\u5ff5 \u5355\u4f8b\u6a21\u5f0f\u662f\u4e00\u79cd\u5e38\u7528\u7684\u8f6f\u4ef6\u8bbe\u8ba1\u6a21\u5f0f\uff0c\u5b83\u786e\u4fdd\u4e00\u4e2a\u7c7b\u53ea\u6709\u4e00\u4e2a\u5b9e\u4f8b\uff0c\u5e76\u63d0\u4f9b\u4e00\u4e2a\u5168\u5c40\u8bbf\u95ee\u70b9\u6765\u83b7\u53d6\u8fd9\u4e2a\u5b9e\u4f8b [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":124,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[18],"class_list":{"0":"post-145","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-8","8":"tag-18"},"_links":{"self":[{"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/posts\/145","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/comments?post=145"}],"version-history":[{"count":2,"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/posts\/145\/revisions"}],"predecessor-version":[{"id":147,"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/posts\/145\/revisions\/147"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/media\/124"}],"wp:attachment":[{"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/media?parent=145"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/categories?post=145"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xzqbear.com\/index.php\/wp-json\/wp\/v2\/tags?post=145"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}