{"id":516,"date":"2020-12-26T16:37:32","date_gmt":"2020-12-26T08:37:32","guid":{"rendered":"http:\/\/blog.refusea.com\/?p=516"},"modified":"2020-12-26T16:37:32","modified_gmt":"2020-12-26T08:37:32","slug":"string-intern-%e5%92%8c%e5%8a%a8%e6%80%81%e5%b8%b8%e9%87%8f%e6%b1%a0","status":"publish","type":"post","link":"https:\/\/refusea.com\/?p=516","title":{"rendered":"String.intern() \u548c\u52a8\u6001\u5e38\u91cf\u6c60"},"content":{"rendered":"<h2>\u80cc\u666f<\/h2>\n<p>\u5148\u770b\u56fe<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/static.refusea.com\/2020\/12\/constantpool.png\" alt=\"\" \/><\/p>\n<p>\u4e0a\u9762\u662f\u4ece\u6570\u636e\u5e93\u91cc\u67e5\u8be2\u51fa\u7684\u5e94\u7528\u4fe1\u606f\uff0c\u8fd9\u6837\u7684\u6570\u636e\u7ed3\u6784\u5728\u6211\u4eec\u7684\u7a0b\u5e8f\u91cc\u5927\u91cf\u5b58\u5728\uff1a\u9664\u4e86\u4e3b\u952e\u4ee5\u5916\uff0c\u5176\u4ed6\u5b57\u6bb5\uff0c\u5c24\u5176\u662f\u5916\u952e\uff0c\u5b58\u5728\u5927\u91cf\u7684\u91cd\u590d\u503c\u3002<\/p>\n<p>\u4ee5\u4e0a\u56fe\u7684\u5e94\u7528\u4fe1\u606f\u4e3a\u4f8b\uff0c\u53ef\u4ee5\u770b\u5230\u7c7b\u522b\u5b57\u6bb5\u7684\u503c\u5c31\u5b58\u5728\u91cd\u590d\uff0c\u5982\u679c\u4ece\u6570\u636e\u5e93\u91cc\u67e5\u8be2\u51fa\u5f53\u524d\u5728\u6295\u5e7f\u544a\u7684\u5e94\u7528\u8be6\u60c5\u5e76\u7f13\u5b58\u8d77\u6765\uff0c\u968f\u7740\u5e94\u7528\u4fe1\u606f\u7684\u589e\u52a0\uff0c\u4f1a\u6d6a\u8d39\u5927\u91cf\u7684\u5185\u5b58<\/p>\n<h2>String.intern()<\/h2>\n<p>\u5173\u4e8e String.intern() \u5c31\u4e0d\u8d58\u8ff0\u4e86\uff0c\u5f88\u9002\u5408\u8fd9\u79cd\u9700\u8981\u7f13\u5b58\u5927\u91cf\u91cd\u590d\u503c\u7684\u573a\u666f\uff0c\u5bf9\u4e8e\u4e0a\u9762\u7684\u5e94\u7528\u4fe1\u606f\uff0c\u53ef\u4ee5\u5982\u4e0b\u4f18\u5316\u5185\u5b58\u7684\u5360\u7528<\/p>\n<pre><code class=\"language-java\">public class App {\n    private Long id;\n    private String name;\n    private String category;\n\n    public App(Long id, String name, String category) {\n        this.id = id;\n        this.name = name;\n        this.category = category.intern();\n    }\n    ......\n}<\/code><\/pre>\n<h2>\u52a8\u6001\u5e38\u91cf\u6c60<\/h2>\n<p>\u4e00\u65b9\u9762\uff0c\u4ec5 String \u63d0\u4f9b\u4e86 <code>intern<\/code> \u8fd9\u6837\u7684\u65b9\u6cd5\uff0c\u5176\u4ed6\u7c7b\u578b\u5e76\u6ca1\u6709\u83b7\u5f97\u539f\u751f\u7684\u5e38\u91cf\u6c60\u652f\u6301\uff1b\u4f46\u662f\uff0c\u5373\u4f7f\u662f int\uff0clong 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\u91cc\u5012\u662f\u6709\u4e00\u4e2a\u73b0\u6210\u7684\u5b9e\u73b0\uff1a<code>Interners<\/code>\uff1b\u5f53\u7136\uff0cguava \u7684\u8fd9\u4e2a\u5b9e\u73b0\u4e5f\u6709\u70b9\u7c97\u7cd9\uff0c\u53ef\u4ee5\u5229\u7528 guava \u7684 <code>LoadingCache<\/code>\uff0c\u5b9e\u73b0\u4e00\u4e2a\u53ef\u63a7\u7684\u5e38\u91cf\u6c60<\/p>\n<pre><code class=\"language-java\">public final class ConstantPool {\n    private ConstantPool() {\n    }\n\n    private static final LoadingCache&lt;String, String&gt;   STRING_CACHE  = CacheBuilder.newBuilder().initialCapacity(512)\n            .expireAfterAccess(24, TimeUnit.HOURS).build(new CacheLoader&lt;String, String&gt;() {\n     @Override\n     public String load(String key) {\n         return key;\n     }\n     });\n\n    private static final LoadingCache&lt;Long, Long&gt;       LONG_CACHE    = CacheBuilder.newBuilder().initialCapacity(512)\n            .expireAfterAccess(24, TimeUnit.HOURS).build(new CacheLoader&lt;Long, Long&gt;() {\n     @Override\n     public Long load(Long key) {\n         return key;\n     }\n     });\n\n    private static final LoadingCache&lt;Integer, Integer&gt; INTEGER_CACHE = CacheBuilder.newBuilder().initialCapacity(512)\n            .expireAfterAccess(24, TimeUnit.HOURS).build(new CacheLoader&lt;Integer, Integer&gt;() {\n     @Override\n     public Integer load(Integer key) {\n         return key;\n     }\n     });\n\n    public static final Integer cint(Integer key) {\n        return key == null ? null : INTEGER_CACHE.getUnchecked(key);\n    }\n\n    public static final Long clong(Long key) {\n        return key == null ? null : LONG_CACHE.getUnchecked(key);\n    }\n\n    public static final String cstr(String key) {\n        return key == null ? null : STRING_CACHE.getUnchecked(key);\n    }\n}<\/code><\/pre>\n<h2>\u603b\u7ed3<\/h2>\n<p>\u4ec0\u4e48\u60c5\u51b5\u7528\u5230\u52a8\u6001\u5e38\u91cf\u6c60\u5462\uff1f<\/p>\n<ul>\n<li>\u9700\u8981\u7f13\u5b58\u5bf9\u8c61\u7684\u573a\u666f\uff0c\u8fd9\u4e9b\u88ab\u7f13\u5b58\u7684\u5bf9\u8c61\u53ef\u80fd\u662f\u4ece\u6570\u636e\u5e93\u91cc\u67e5\u8be2\u5f97\u6765\u7684\uff0c\u6216\u8005\u662f\u4ece\u4e00\u4e9b\u7b2c\u4e09\u65b9\u63a5\u53e3\u83b7\u53d6\u7684<\/li>\n<li>\u88ab\u7f13\u5b58\u7684\u5bf9\u8c61\uff0c\u67d0\u4e9b\u5c5e\u6027\u6709\u5927\u91cf\u7684\u91cd\u590d\u503c\uff1b\u4f8b\u5982\uff0c\u4e0a\u9762\u4f8b\u5b50\u91cc\u7684\u5e94\u7528\u5206\u7c7b\u5b57\u6bb5<\/li>\n<li>\u6216\u8005\uff0c\u67d0\u4e2a\u5c5e\u6027\u5728\u591a\u4e2a\u88ab\u7f13\u5b58\u7684\u5bf9\u8c61\u91cc\u5b58\u5728\uff1b\u4f8b\u5982\uff0c\u5e94\u7528 Id \u672c\u8eab\u51e0\u4e4e\u4e0d\u4f1a\u91cd\u590d\uff0c\u4f46\u662f\u6709\u591a\u4e2a\u573a\u5408\u90fd\u9700\u8981\u7528\u5e94\u7528 Id \u4f5c\u4e3a\u7f13\u5b58\u7684 Key\u6765\u6620\u5c04\u4e0d\u540c\u7684\u5bf9\u8c61\u503c<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\u80cc\u666f \u5148\u770b\u56fe \u4e0a\u9762\u662f\u4ece\u6570\u636e\u5e93\u91cc\u67e5\u8be2\u51fa\u7684\u5e94\u7528\u4fe1\u606f\uff0c\u8fd9\u6837\u7684\u6570\u636e\u7ed3\u6784\u5728\u6211\u4eec\u7684\u7a0b\u5e8f\u91cc\u5927\u91cf\u5b58\u5728\uff1a\u9664\u4e86\u4e3b\u952e\u4ee5\u5916\uff0c\u5176\u4ed6\u5b57\u6bb5\uff0c [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-516","post","type-post","status-publish","format-standard","hentry","category-java"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.3 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>String.intern() \u548c\u52a8\u6001\u5e38\u91cf\u6c60 - \u62d2\u6d77\u7a7a\u95f4<\/title>\n<meta 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