{"id":544,"date":"2025-09-15T17:14:14","date_gmt":"2025-09-15T09:14:14","guid":{"rendered":"https:\/\/trantor.ink\/?p=544"},"modified":"2025-09-15T17:14:15","modified_gmt":"2025-09-15T09:14:15","slug":"%e7%8a%b6%e6%80%81%e6%9c%ba%e8%ae%be%e8%ae%a1%e6%a8%a1%e5%bc%8f","status":"publish","type":"post","link":"https:\/\/trantor.ink\/?p=544","title":{"rendered":"\u72b6\u6001\u673a\u8bbe\u8ba1\u6a21\u5f0f"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_81 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/trantor.ink\/?p=544\/#%E4%B8%80%E3%80%81%E7%8A%B6%E6%80%81%E6%9C%BA%E8%AE%BE%E8%AE%A1%E6%A8%A1%E5%BC%8F%E7%9A%84%E6%A0%B8%E5%BF%83%E6%80%9D%E6%83%B3\" >\u4e00\u3001\u72b6\u6001\u673a\u8bbe\u8ba1\u6a21\u5f0f\u7684\u6838\u5fc3\u601d\u60f3<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/trantor.ink\/?p=544\/#1_%E5%AE%9A%E4%B9%89\" >1. \u5b9a\u4e49<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/trantor.ink\/?p=544\/#2_%E9%80%82%E7%94%A8%E5%9C%BA%E6%99%AF\" >2. \u9002\u7528\u573a\u666f<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/trantor.ink\/?p=544\/#3_%E4%BC%98%E7%82%B9\" >3. \u4f18\u70b9<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/trantor.ink\/?p=544\/#4_%E7%BC%BA%E7%82%B9\" >4. \u7f3a\u70b9<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/trantor.ink\/?p=544\/#%E4%BA%8C%E3%80%81%E7%8A%B6%E6%80%81%E6%A8%A1%E5%BC%8F%E7%9A%84%E7%BB%93%E6%9E%84\" >\u4e8c\u3001\u72b6\u6001\u6a21\u5f0f\u7684\u7ed3\u6784<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/trantor.ink\/?p=544\/#UML_%E7%B1%BB%E5%9B%BE\" >UML \u7c7b\u56fe<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/trantor.ink\/?p=544\/#%E4%B8%89%E3%80%81Kotlin_%E7%A4%BA%E4%BE%8B\" >\u4e09\u3001Kotlin \u793a\u4f8b<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/trantor.ink\/?p=544\/#1_%E5%AE%9A%E4%B9%89%E7%8A%B6%E6%80%81%E6%8E%A5%E5%8F%A3\" >1. \u5b9a\u4e49\u72b6\u6001\u63a5\u53e3<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/trantor.ink\/?p=544\/#2_%E5%85%B7%E4%BD%93%E7%8A%B6%E6%80%81%E7%B1%BB\" >2. \u5177\u4f53\u72b6\u6001\u7c7b<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/trantor.ink\/?p=544\/#3_%E7%8E%AF%E5%A2%83%E7%B1%BB%EF%BC%88Context%EF%BC%89\" >3. \u73af\u5883\u7c7b\uff08Context\uff09<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/trantor.ink\/?p=544\/#4_%E4%BD%BF%E7%94%A8%E7%A4%BA%E4%BE%8B\" >4. \u4f7f\u7528\u793a\u4f8b<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/trantor.ink\/?p=544\/#%E5%9B%9B%E3%80%81Kotlin_%E4%B8%AD%E7%9A%84%E6%94%B9%E8%BF%9B%E5%86%99%E6%B3%95\" >\u56db\u3001Kotlin \u4e2d\u7684\u6539\u8fdb\u5199\u6cd5<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/trantor.ink\/?p=544\/#%E4%BD%BF%E7%94%A8\" >\u4f7f\u7528&nbsp;<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/trantor.ink\/?p=544\/#sealed_class\" >sealed class<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/trantor.ink\/?p=544\/#_%E9%87%8D%E5%86%99\" >&nbsp;\u91cd\u5199<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/trantor.ink\/?p=544\/#%E4%BA%94%E3%80%81%E5%AF%B9%E6%AF%94_if-else_%E7%9A%84%E4%BC%98%E5%8A%BF\" >\u4e94\u3001\u5bf9\u6bd4 if-else \u7684\u4f18\u52bf<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/trantor.ink\/?p=544\/#%E5%85%AD%E3%80%81%E6%80%BB%E7%BB%93\" >\u516d\u3001\u603b\u7ed3<\/a><\/li><\/ul><\/nav><\/div>\n\n<p class=\"wp-block-paragraph\">\u597d\u7684 \ud83d\udc4d\uff0c\u6211\u4eec\u6765<strong>\u7cfb\u7edf\u4e14\u8be6\u7ec6\u5730\u4ecb\u7ecd\u72b6\u6001\u673a\u8bbe\u8ba1\u6a21\u5f0f\uff08State Pattern\uff0c\u72b6\u6001\u6a21\u5f0f\uff09<\/strong>\uff0c\u5e76\u7ed3\u5408 <strong>Kotlin \u793a\u4f8b<\/strong>\u8bb2\u89e3\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E4%B8%80%E3%80%81%E7%8A%B6%E6%80%81%E6%9C%BA%E8%AE%BE%E8%AE%A1%E6%A8%A1%E5%BC%8F%E7%9A%84%E6%A0%B8%E5%BF%83%E6%80%9D%E6%83%B3\"><\/span><strong>\u4e00\u3001\u72b6\u6001\u673a\u8bbe\u8ba1\u6a21\u5f0f\u7684\u6838\u5fc3\u601d\u60f3<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"1_%E5%AE%9A%E4%B9%89\"><\/span><strong>1. \u5b9a\u4e49<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">**\u72b6\u6001\u6a21\u5f0f\uff08State Pattern\uff09**\u662f\u4e00\u79cd\u884c\u4e3a\u578b\u8bbe\u8ba1\u6a21\u5f0f\uff0c\u5b83\u5141\u8bb8\u4e00\u4e2a\u5bf9\u8c61\u5728\u5176\u5185\u90e8\u72b6\u6001\u6539\u53d8\u65f6\u6539\u53d8\u5b83\u7684\u884c\u4e3a\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6362\u53e5\u8bdd\u8bf4\uff1a\u72b6\u6001\u6a21\u5f0f\u5c06\u5bf9\u8c61\u7684\u884c\u4e3a\u5c01\u88c5\u5230\u4e0d\u540c\u7684\u72b6\u6001\u7c7b\u4e2d\uff0c\u4f7f\u5f97\u5bf9\u8c61\u5728\u4e0d\u540c\u72b6\u6001\u4e0b\u8868\u73b0\u51fa\u4e0d\u540c\u7684\u884c\u4e3a\uff0c\u800c\u4e0d\u662f\u901a\u8fc7\u5197\u957f\u7684 if-else \u6216 when \u6765\u786c\u7f16\u7801\u72b6\u6001\u5207\u6362\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"2_%E9%80%82%E7%94%A8%E5%9C%BA%E6%99%AF\"><\/span><strong>2. \u9002\u7528\u573a\u666f<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u5bf9\u8c61\u6709\u591a\u79cd\u72b6\u6001<\/strong>\uff0c\u5e76\u4e14\u5728\u4e0d\u540c\u72b6\u6001\u4e0b\u8868\u73b0\u4e0d\u540c\u884c\u4e3a\u3002<\/li>\n\n\n\n<li><strong>\u72b6\u6001\u8f6c\u6362\u903b\u8f91\u590d\u6742<\/strong>\uff0c\u4ee3\u7801\u4e2d\u51fa\u73b0\u4e86\u5927\u91cf if-else \u6216 switch\/when \u5206\u652f\u3002<\/li>\n\n\n\n<li>\u5e0c\u671b <strong>\u72b6\u6001\u5207\u6362\u548c\u884c\u4e3a\u89e3\u8026<\/strong>\uff0c\u907f\u514d\u5728\u4e3b\u903b\u8f91\u7c7b\u4e2d\u5806\u79ef\u8fc7\u591a\u72b6\u6001\u903b\u8f91\u3002<\/li>\n\n\n\n<li>\u5e0c\u671b\u65b0\u589e\u72b6\u6001\u65f6\u4e0d\u4fee\u6539\u539f\u6709\u4ee3\u7801\uff0c\u53ea\u9700\u6269\u5c55\u65b0\u7684\u72b6\u6001\u7c7b\uff08\u7b26\u5408\u5f00\u95ed\u539f\u5219\uff09\u3002<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u5e38\u89c1\u5e94\u7528\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u64ad\u653e\u5668\uff08\u64ad\u653e\u3001\u6682\u505c\u3001\u505c\u6b62\uff09<\/li>\n\n\n\n<li>\u8ba2\u5355\u6d41\u7a0b\uff08\u5f85\u652f\u4ed8\u3001\u5df2\u652f\u4ed8\u3001\u53d1\u8d27\u4e2d\u3001\u5b8c\u6210\uff09<\/li>\n\n\n\n<li>\u5de5\u4f5c\u6d41\u5f15\u64ce\uff08\u8349\u7a3f\u3001\u5ba1\u6838\u4e2d\u3001\u5df2\u53d1\u5e03\uff09<\/li>\n\n\n\n<li>\u7f51\u7edc\u8fde\u63a5\uff08\u8fde\u63a5\u4e2d\u3001\u5df2\u8fde\u63a5\u3001\u65ad\u5f00\uff09<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"3_%E4%BC%98%E7%82%B9\"><\/span><strong>3. \u4f18\u70b9<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u6e05\u6670\u53ef\u7ef4\u62a4<\/strong>\uff1a\u907f\u514d\u72b6\u6001\u76f8\u5173\u7684\u5927\u91cf\u6761\u4ef6\u5206\u652f\u3002<\/li>\n\n\n\n<li><strong>\u6269\u5c55\u6027\u597d<\/strong>\uff1a\u65b0\u589e\u72b6\u6001\u53ea\u9700\u589e\u52a0\u4e00\u4e2a\u7c7b\u3002<\/li>\n\n\n\n<li><strong>\u804c\u8d23\u5355\u4e00<\/strong>\uff1a\u6bcf\u4e2a\u72b6\u6001\u7c7b\u53ea\u5173\u5fc3\u81ea\u5df1\u7684\u884c\u4e3a\u548c\u72b6\u6001\u8f6c\u6362\u3002<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"4_%E7%BC%BA%E7%82%B9\"><\/span><strong>4. \u7f3a\u70b9<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u7c7b\u6570\u91cf\u589e\u52a0<\/strong>\uff1a\u6bcf\u4e2a\u72b6\u6001\u5bf9\u5e94\u4e00\u4e2a\u7c7b\uff0c\u72b6\u6001\u8fc7\u591a\u65f6\u4f1a\u81a8\u80c0\u3002<\/li>\n\n\n\n<li><strong>\u72b6\u6001\u7c7b\u95f4\u8026\u5408<\/strong>\uff1a\u67d0\u4e9b\u72b6\u6001\u9700\u8981\u4e86\u89e3\u5176\u4ed6\u72b6\u6001\u7c7b\u7684\u5b58\u5728\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E4%BA%8C%E3%80%81%E7%8A%B6%E6%80%81%E6%A8%A1%E5%BC%8F%E7%9A%84%E7%BB%93%E6%9E%84\"><\/span><strong>\u4e8c\u3001\u72b6\u6001\u6a21\u5f0f\u7684\u7ed3\u6784<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"UML_%E7%B1%BB%E5%9B%BE\"><\/span><strong>UML \u7c7b\u56fe<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">          \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\n          \u2502   Context     \u2502\n          \u2502 (\u73af\u5883\u7c7b)       \u2502\n          \u2502 - state:State \u2502\n          \u2502 + request()   \u2502\n          \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u25b2\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518\n                  \u2502\n          \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\n          \u2502                 \u2502\n   \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510   \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\n   \u2502  State       \u2502   \u2502 ConcreteState\u2502\n   \u2502 (\u62bd\u8c61\u72b6\u6001)   \u2502   \u2502 (\u5177\u4f53\u72b6\u6001)   \u2502\n   \u2502 + handle()   \u2502   \u2502 + handle()   \u2502\n   \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518   \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Context\uff08\u73af\u5883\u7c7b\uff09<\/strong>\uff1a\u6301\u6709\u5f53\u524d\u72b6\u6001\u5bf9\u8c61\uff0c\u5916\u90e8\u8c03\u7528\u5165\u53e3\u3002<\/li>\n\n\n\n<li><strong>State\uff08\u62bd\u8c61\u72b6\u6001\uff09<\/strong>\uff1a\u5b9a\u4e49\u72b6\u6001\u63a5\u53e3\u3002<\/li>\n\n\n\n<li><strong>ConcreteState\uff08\u5177\u4f53\u72b6\u6001\uff09<\/strong>\uff1a\u5b9e\u73b0\u4e0d\u540c\u72b6\u6001\u4e0b\u7684\u884c\u4e3a\u903b\u8f91\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E4%B8%89%E3%80%81Kotlin_%E7%A4%BA%E4%BE%8B\"><\/span><strong>\u4e09\u3001Kotlin \u793a\u4f8b<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u6211\u4eec\u4ee5 <strong>\u97f3\u4e50\u64ad\u653e\u5668\uff08\u64ad\u653e\u3001\u6682\u505c\u3001\u505c\u6b62\uff09<\/strong> \u4e3a\u4f8b\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"1_%E5%AE%9A%E4%B9%89%E7%8A%B6%E6%80%81%E6%8E%A5%E5%8F%A3\"><\/span><strong>1. \u5b9a\u4e49\u72b6\u6001\u63a5\u53e3<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u72b6\u6001\u63a5\u53e3\ninterface PlayerState {\n    fun play(context: MusicPlayer)\n    fun pause(context: MusicPlayer)\n    fun stop(context: MusicPlayer)\n}<\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"2_%E5%85%B7%E4%BD%93%E7%8A%B6%E6%80%81%E7%B1%BB\"><\/span><strong>2. \u5177\u4f53\u72b6\u6001\u7c7b<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u64ad\u653e\u72b6\u6001\nclass PlayingState : PlayerState {\n    override fun play(context: MusicPlayer) {\n        println(\"\u5df2\u7ecf\u5728\u64ad\u653e\uff0c\u65e0\u9700\u91cd\u590d\u64ad\u653e\")\n    }\n\n    override fun pause(context: MusicPlayer) {\n        println(\"\u6682\u505c\u64ad\u653e\")\n        context.changeState(PausedState())\n    }\n\n    override fun stop(context: MusicPlayer) {\n        println(\"\u505c\u6b62\u64ad\u653e\")\n        context.changeState(StoppedState())\n    }\n}\n\n\/\/ \u6682\u505c\u72b6\u6001\nclass PausedState : PlayerState {\n    override fun play(context: MusicPlayer) {\n        println(\"\u7ee7\u7eed\u64ad\u653e\")\n        context.changeState(PlayingState())\n    }\n\n    override fun pause(context: MusicPlayer) {\n        println(\"\u5df2\u7ecf\u6682\u505c\")\n    }\n\n    override fun stop(context: MusicPlayer) {\n        println(\"\u4ece\u6682\u505c\u72b6\u6001\u505c\u6b62\u64ad\u653e\")\n        context.changeState(StoppedState())\n    }\n}\n\n\/\/ \u505c\u6b62\u72b6\u6001\nclass StoppedState : PlayerState {\n    override fun play(context: MusicPlayer) {\n        println(\"\u5f00\u59cb\u64ad\u653e\")\n        context.changeState(PlayingState())\n    }\n\n    override fun pause(context: MusicPlayer) {\n        println(\"\u65e0\u6cd5\u6682\u505c\uff0c\u5f53\u524d\u5df2\u505c\u6b62\")\n    }\n\n    override fun stop(context: MusicPlayer) {\n        println(\"\u5df2\u7ecf\u505c\u6b62\")\n    }\n}<\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"3_%E7%8E%AF%E5%A2%83%E7%B1%BB%EF%BC%88Context%EF%BC%89\"><\/span><strong>3. \u73af\u5883\u7c7b\uff08Context\uff09<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class MusicPlayer {\n    private var state: PlayerState = StoppedState() \/\/ \u521d\u59cb\u4e3a\u505c\u6b62\u72b6\u6001\n\n    fun changeState(newState: PlayerState) {\n        state = newState\n    }\n\n    fun play() = state.play(this)\n    fun pause() = state.pause(this)\n    fun stop() = state.stop(this)\n}<\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"4_%E4%BD%BF%E7%94%A8%E7%A4%BA%E4%BE%8B\"><\/span><strong>4. \u4f7f\u7528\u793a\u4f8b<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">fun main() {\n    val player = MusicPlayer()\n\n    player.play()   \/\/ \u5f00\u59cb\u64ad\u653e\n    player.pause()  \/\/ \u6682\u505c\u64ad\u653e\n    player.play()   \/\/ \u7ee7\u7eed\u64ad\u653e\n    player.stop()   \/\/ \u505c\u6b62\u64ad\u653e\n    player.pause()  \/\/ \u65e0\u6cd5\u6682\u505c\uff0c\u5f53\u524d\u5df2\u505c\u6b62\n}<\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%9B%9B%E3%80%81Kotlin_%E4%B8%AD%E7%9A%84%E6%94%B9%E8%BF%9B%E5%86%99%E6%B3%95\"><\/span><strong>\u56db\u3001Kotlin \u4e2d\u7684\u6539\u8fdb\u5199\u6cd5<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u7531\u4e8e Kotlin \u652f\u6301 <strong>sealed class \/ sealed interface<\/strong>\uff0c\u6211\u4eec\u53ef\u4ee5\u8ba9\u72b6\u6001\u5b9a\u4e49\u66f4\u7b80\u6d01\uff0c\u907f\u514d\u8fc7\u591a\u7c7b\u6587\u4ef6\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E4%BD%BF%E7%94%A8\"><\/span><strong>\u4f7f\u7528&nbsp;<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"sealed_class\"><\/span><strong>sealed class<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"_%E9%87%8D%E5%86%99\"><\/span><strong>&nbsp;\u91cd\u5199<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">sealed class PlayerState {\n    abstract fun play(context: MusicPlayer)\n    abstract fun pause(context: MusicPlayer)\n    abstract fun stop(context: MusicPlayer)\n\n    object Playing : PlayerState() {\n        override fun play(context: MusicPlayer) = println(\"\u5df2\u7ecf\u5728\u64ad\u653e\")\n        override fun pause(context: MusicPlayer) {\n            println(\"\u6682\u505c\u64ad\u653e\")\n            context.changeState(Paused)\n        }\n        override fun stop(context: MusicPlayer) {\n            println(\"\u505c\u6b62\u64ad\u653e\")\n            context.changeState(Stopped)\n        }\n    }\n\n    object Paused : PlayerState() {\n        override fun play(context: MusicPlayer) {\n            println(\"\u7ee7\u7eed\u64ad\u653e\")\n            context.changeState(Playing)\n        }\n        override fun pause(context: MusicPlayer) = println(\"\u5df2\u7ecf\u6682\u505c\")\n        override fun stop(context: MusicPlayer) {\n            println(\"\u4ece\u6682\u505c\u72b6\u6001\u505c\u6b62\u64ad\u653e\")\n            context.changeState(Stopped)\n        }\n    }\n\n    object Stopped : PlayerState() {\n        override fun play(context: MusicPlayer) {\n            println(\"\u5f00\u59cb\u64ad\u653e\")\n            context.changeState(Playing)\n        }\n        override fun pause(context: MusicPlayer) = println(\"\u65e0\u6cd5\u6682\u505c\uff0c\u5f53\u524d\u5df2\u505c\u6b62\")\n        override fun stop(context: MusicPlayer) = println(\"\u5df2\u7ecf\u505c\u6b62\")\n    }\n}\n\nclass MusicPlayer {\n    private var state: PlayerState = PlayerState.Stopped\n\n    fun changeState(newState: PlayerState) {\n        state = newState\n    }\n\n    fun play() = state.play(this)\n    fun pause() = state.pause(this)\n    fun stop() = state.stop(this)\n}<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u79cd\u5199\u6cd5\u4f18\u70b9\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u6240\u6709\u72b6\u6001\u96c6\u4e2d\u7ba1\u7406<\/strong>\uff0c\u907f\u514d\u7c7b\u6587\u4ef6\u8fc7\u591a\u3002<\/li>\n\n\n\n<li><strong>\u7f16\u8bd1\u5668\u68c0\u67e5<\/strong>\uff1asealed class \u8ba9\u72b6\u6001\u6269\u5c55\u53d7\u9650\uff0c\u907f\u514d\u9057\u6f0f\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E4%BA%94%E3%80%81%E5%AF%B9%E6%AF%94_if-else_%E7%9A%84%E4%BC%98%E5%8A%BF\"><\/span><strong>\u4e94\u3001\u5bf9\u6bd4 if-else \u7684\u4f18\u52bf<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u5982\u679c\u7528\u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class MusicPlayer {\n    private var state = \"stopped\"\n\n    fun play() {\n        when (state) {\n            \"playing\" -> println(\"\u5df2\u7ecf\u5728\u64ad\u653e\")\n            \"paused\" -> {\n                println(\"\u7ee7\u7eed\u64ad\u653e\")\n                state = \"playing\"\n            }\n            \"stopped\" -> {\n                println(\"\u5f00\u59cb\u64ad\u653e\")\n                state = \"playing\"\n            }\n        }\n    }\n\n    \/\/ \u7701\u7565 pause, stop...\n}<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u7f3a\u70b9\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u72b6\u6001\u903b\u8f91\u5206\u6563\u5728 when\/if \u4e2d\uff0c\u7ef4\u62a4\u56f0\u96be\u3002<\/li>\n\n\n\n<li>\u65b0\u589e\u72b6\u6001\u9700\u8981\u4fee\u6539\u591a\u4e2a\u5730\u65b9\u3002<\/li>\n\n\n\n<li>\u5bb9\u6613\u9057\u6f0f\u72b6\u6001\u5206\u652f\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%85%AD%E3%80%81%E6%80%BB%E7%BB%93\"><\/span><strong>\u516d\u3001\u603b\u7ed3<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li><strong>\u72b6\u6001\u6a21\u5f0f\u5b9a\u4e49<\/strong>\uff1a\u901a\u8fc7\u5c06\u72b6\u6001\u5c01\u88c5\u4e3a\u7c7b\uff0c\u4f7f\u5bf9\u8c61\u5728\u4e0d\u540c\u72b6\u6001\u4e0b\u884c\u4e3a\u4e0d\u540c\uff0c\u907f\u514d\u590d\u6742\u6761\u4ef6\u5206\u652f\u3002<\/li>\n\n\n\n<li><strong>\u6838\u5fc3\u89d2\u8272<\/strong>\uff1aContext\uff08\u73af\u5883\u7c7b\uff09\u3001State\uff08\u62bd\u8c61\u72b6\u6001\uff09\u3001ConcreteState\uff08\u5177\u4f53\u72b6\u6001\uff09\u3002<\/li>\n\n\n\n<li><strong>Kotlin \u5b9e\u73b0\u65b9\u5f0f<\/strong>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u4f20\u7edf\u63a5\u53e3 + \u591a\u4e2a\u72b6\u6001\u7c7b\u3002<\/li>\n\n\n\n<li>sealed class \u96c6\u4e2d\u5f0f\u5b9e\u73b0\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u9002\u7528\u573a\u666f<\/strong>\uff1a\u6d41\u7a0b\u63a7\u5236\u3001\u64ad\u653e\u5668\u3001\u8ba2\u5355\u3001\u5de5\u4f5c\u6d41\u7b49\u3002<\/li>\n\n\n\n<li><strong>\u4f18\u70b9<\/strong>\uff1a\u7b80\u5316\u903b\u8f91\u3001\u53ef\u6269\u5c55\u6027\u5f3a\u3001\u804c\u8d23\u6e05\u6670\u3002<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>\u597d\u7684 \ud83d\udc4d\uff0c\u6211\u4eec\u6765\u7cfb\u7edf\u4e14\u8be6\u7ec6\u5730\u4ecb\u7ecd\u72b6\u6001\u673a\u8bbe\u8ba1\u6a21\u5f0f\uff08State Pattern\uff0c\u72b6\u6001\u6a21\u5f0f\uff09\uff0c\u5e76\u7ed3\u5408 Kotlin \u793a\u4f8b\u8bb2\u89e3\u3002 \u4e00\u3001\u72b6\u6001\u673a\u8bbe\u8ba1\u6a21\u5f0f\u7684\u6838\u5fc3\u601d\u60f3 1. \u5b9a\u4e49 **\u72b6\u6001\u6a21\u5f0f\uff08State Pattern\uff09**\u662f\u4e00\u79cd\u884c\u4e3a\u578b\u8bbe\u8ba1\u6a21\u5f0f\uff0c\u5b83\u5141\u8bb8\u4e00\u4e2a\u5bf9\u8c61\u5728\u5176\u5185\u90e8\u72b6\u6001\u6539\u53d8\u65f6\u6539\u53d8\u5b83\u7684\u884c\u4e3a\u3002 \u6362\u53e5\u8bdd\u8bf4\uff1a\u72b6\u6001\u6a21\u5f0f\u5c06\u5bf9\u8c61\u7684\u884c\u4e3a\u5c01\u88c5\u5230\u4e0d\u540c\u7684\u72b6\u6001\u7c7b\u4e2d\uff0c\u4f7f\u5f97\u5bf9\u8c61\u5728\u4e0d\u540c\u72b6\u6001\u4e0b\u8868\u73b0\u51fa\u4e0d\u540c\u7684\u884c\u4e3a\uff0c\u800c\u4e0d\u662f\u901a\u8fc7\u5197\u957f\u7684 if-else \u6216 when \u6765\u786c\u7f16\u7801\u72b6\u6001\u5207\u6362\u3002 2. \u9002\u7528\u573a\u666f \u5e38\u89c1\u5e94\u7528\uff1a 3. \u4f18\u70b9 4. \u7f3a\u70b9 \u4e8c\u3001\u72b6\u6001\u6a21\u5f0f\u7684\u7ed3\u6784 UML \u7c7b\u56fe \u4e09\u3001Kotlin \u793a\u4f8b \u6211\u4eec\u4ee5 \u97f3\u4e50\u64ad\u653e\u5668\uff08\u64ad\u653e\u3001\u6682\u505c\u3001\u505c\u6b62\uff09 \u4e3a\u4f8b\u3002 1. \u5b9a\u4e49\u72b6\u6001\u63a5\u53e3 2. \u5177\u4f53\u72b6\u6001\u7c7b 3. \u73af\u5883\u7c7b\uff08Context\uff09 4. \u4f7f\u7528\u793a\u4f8b \u56db\u3001Kotlin \u4e2d\u7684\u6539\u8fdb\u5199\u6cd5 \u7531\u4e8e Kotlin \u652f\u6301 sealed class \/ sealed interface\uff0c\u6211\u4eec\u53ef\u4ee5\u8ba9\u72b6\u6001\u5b9a\u4e49\u66f4\u7b80\u6d01\uff0c\u907f\u514d\u8fc7\u591a\u7c7b\u6587\u4ef6\u3002 \u4f7f\u7528&nbsp; sealed class &nbsp;\u91cd\u5199 \u8fd9\u79cd\u5199\u6cd5\u4f18\u70b9\uff1a \u4e94\u3001\u5bf9\u6bd4 if-else \u7684\u4f18\u52bf \u5982\u679c\u7528\u4f20\u7edf\u5199\u6cd5\uff1a \u7f3a\u70b9\uff1a \u516d\u3001\u603b\u7ed3<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[66],"class_list":["post-544","post","type-post","status-publish","format-standard","hentry","category-dev","tag-66"],"_links":{"self":[{"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/posts\/544","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/trantor.ink\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=544"}],"version-history":[{"count":1,"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/posts\/544\/revisions"}],"predecessor-version":[{"id":545,"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/posts\/544\/revisions\/545"}],"wp:attachment":[{"href":"https:\/\/trantor.ink\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=544"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/trantor.ink\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=544"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/trantor.ink\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=544"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}