\u5728 JAVA \u8bed\u8a00\u4e2d\u67098\u4e2d\u57fa\u672c\u7c7b\u578b\u548c\u4e00\u79cd\u6bd4\u8f83\u7279\u6b8a\u7684\u7c7b\u578bString\u3002\u8fd9\u4e9b\u7c7b\u578b\u4e3a\u4e86\u4f7f\u4ed6\u4eec\u5728\u8fd0\u884c\u8fc7\u7a0b\u4e2d\u901f\u5ea6\u66f4\u5feb\uff0c\u66f4\u8282\u7701\u5185\u5b58\uff0c\u90fd\u63d0\u4f9b\u4e86\u4e00\u79cd\u5e38\u91cf\u6c60\u7684\u6982\u5ff5\u3002\u5e38\u91cf\u6c60\u5c31\u7c7b\u4f3c\u4e00\u4e2aJAVA\u7cfb\u7edf\u7ea7\u522b\u63d0\u4f9b\u7684\u7f13\u5b58\u3002<\/p>\n
8\u79cd\u57fa\u672c\u7c7b\u578b\u7684\u5e38\u91cf\u6c60\u90fd\u662f\u7cfb\u7edf\u534f\u8c03\u7684\uff0cString\u7c7b\u578b\u7684\u5e38\u91cf\u6c60\u6bd4\u8f83\u7279\u6b8a\u3002<\/p>\n
\u5b83\u7684\u4e3b\u8981\u4f7f\u7528\u65b9\u6cd5\u6709\u4e24\u79cd\uff1a<\/p>\n
- \n
- \u76f4\u63a5\u4f7f\u7528\u53cc\u5f15\u53f7\u58f0\u660e\u51fa\u6765\u7684String\u5bf9\u8c61\u4f1a\u76f4\u63a5\u5b58\u50a8\u5728\u5e38\u91cf\u6c60\u4e2d\u3002<\/li>\n
- \u5982\u679c\u4e0d\u662f\u7528\u53cc\u5f15\u53f7\u58f0\u660e\u7684String\u5bf9\u8c61\uff0c\u53ef\u4ee5\u4f7f\u7528String\u63d0\u4f9b\u7684intern\u65b9\u6cd5\u3002intern \u65b9\u6cd5\u4f1a\u4ece\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u4e2d\u67e5\u8be2\u5f53\u524d\u5b57\u7b26\u4e32\u662f\u5426\u5b58\u5728\uff0c\u82e5\u4e0d\u5b58\u5728\u5c31\u4f1a\u5c06\u5f53\u524d\u5b57\u7b26\u4e32\u653e\u5165\u5e38\u91cf\u6c60\u4e2d<\/li>\n<\/ul>\n
\u63a8\u8350\u4e00\u4e2a\u5f00\u6e90\u514d\u8d39\u7684 Spring Boot \u5b9e\u6218\u9879\u76ee\uff1a<\/p>\n
https:\/\/github.com\/javastacks\/spring-boot-best-practice<\/a><\/p><\/blockquote>\n
1. \u5e38\u91cf\u6c60<\/strong><\/h2>\n
1.1 \u5e38\u91cf\u6c60\u662f\u4ec0\u4e48\uff1f<\/h3>\n
<\/p>\n
JVM\u5e38\u91cf\u6c60\u4e3b\u8981\u5206\u4e3aClass\u6587\u4ef6\u5e38\u91cf\u6c60\u3001\u8fd0\u884c\u65f6\u5e38\u91cf\u6c60\uff0c\u5168\u5c40\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\uff0c\u4ee5\u53ca\u57fa\u672c\u7c7b\u578b\u5305\u88c5\u7c7b\u5bf9\u8c61\u5e38\u91cf\u6c60<\/p>\n
1.1.0 \u65b9\u6cd5\u533a<\/h4>\n
\u65b9\u6cd5\u533a\u7684\u4f5c\u7528\u662f\u5b58\u50a8Java\u7c7b\u7684\u7ed3\u6784\u4fe1\u606f\uff0c\u5f53\u521b\u5efa\u5bf9\u8c61\u540e\uff0c\u5bf9\u8c61\u7684\u7c7b\u578b\u4fe1\u606f\u5b58\u50a8\u5728\u65b9\u6cd5\u533a\u4e2d\uff0c\u5b9e\u4f8b\u6570\u636e\u5b58\u653e\u5728\u5806\u4e2d\u3002\u7c7b\u578b\u4fe1\u606f\u662f\u5b9a\u4e49\u5728Java\u4ee3\u7801\u4e2d\u7684\u5e38\u91cf\u3001\u9759\u6001\u53d8\u91cf\u3001\u4ee5\u53ca\u7c7b\u4e2d\u58f0\u660e\u7684\u5404\u79cd\u65b9\u6cd5\uff0c\u65b9\u6cd5\u5b57\u6bb5\u7b49\uff1b\u5b9e\u4f8b\u6570\u636e\u5219\u662f\u5728Java\u4e2d\u521b\u5efa\u7684\u5bf9\u8c61\u5b9e\u4f8b\u4ee5\u53ca\u4ed6\u4eec\u7684\u503c\u3002<\/p>\n
\u8be5\u533a\u57df\u8fdb\u884c\u5185\u5b58\u56de\u6536\u7684\u4e3b\u8981\u76ee\u7684\u662f\u5bf9\u5e38\u91cf\u6c60\u7684\u56de\u6536\u548c\u5bf9\u5185\u5b58\u6570\u636e\u7684\u5378\u8f7d\uff1b\u4e00\u822c\u8bf4\u8fd9\u4e2a\u533a\u57df\u7684\u5185\u5b58\u56de\u6536\u7387\u6bd4\u8d77Java\u5806\u4f4e\u5f97\u591a\u3002<\/p>\n
1.1.1 Class\u6587\u4ef6\u5e38\u91cf\u6c60<\/h4>\n
class\u6587\u4ef6\u662f\u4e00\u7ec4\u4ee5\u5b57\u8282\u4e3a\u5355\u4f4d\u7684\u4e8c\u8fdb\u5236\u6570\u636e\u6d41\uff0c\u5728Java\u4ee3\u7801\u7684\u7f16\u8bd1\u671f\u95f4\uff0c\u6211\u4eec\u7f16\u5199\u7684Java\u6587\u4ef6\u5c31\u88ab\u7f16\u8bd1\u4e3a.class\u6587\u4ef6\u683c\u5f0f\u7684\u4e8c\u8fdb\u5236\u6570\u636e\u5b58\u653e\u5728\u78c1\u76d8\u4e2d\uff0c\u5176\u4e2d\u5c31\u5305\u62ecclass\u6587\u4ef6\u5e38\u91cf\u6c60\u3002<\/p>\n
class\u6587\u4ef6\u5e38\u91cf\u6c60\u4e3b\u8981\u5b58\u653e\u4e24\u5927\u5e38\u91cf\uff1a\u5b57\u9762\u91cf\u548c\u7b26\u53f7\u5f15\u7528<\/strong>\u3002<\/p>\n
\u5b57\u9762\u91cf\uff1a\u5b57\u9762\u91cf\u63a5\u8fd1java\u8bed\u8a00\u5c42\u9762\u7684\u5e38\u91cf\u6982\u5ff5<\/p>\n
- \n
- \u6587\u672c\u5b57\u7b26\u4e32\uff0c\u4e5f\u5c31\u662f\u6211\u4eec\u7ecf\u5e38\u7533\u660e\u7684\uff1apublic String s = “abc”;\u4e2d\u7684”abc”<\/li>\n
- \u7528final\u4fee\u9970\u7684\u6210\u5458\u53d8\u91cf\uff0c\u5305\u62ec\u9759\u6001\u53d8\u91cf\u3001\u5b9e\u4f8b\u53d8\u91cf\u548c\u5c40\u90e8\u53d8\u91cf\uff1apublic final static int f = 0x101;,final int temp = 3;<\/li>\n
- \u800c\u5bf9\u4e8e\u57fa\u672c\u7c7b\u578b\u6570\u636e(\u751a\u81f3\u662f\u65b9\u6cd5\u4e2d\u7684\u5c40\u90e8\u53d8\u91cf)\uff0c\u5982int value = 1\u5e38\u91cf\u6c60\u4e2d\u53ea\u4fdd\u7559\u4e86\u4ed6\u7684\u7684\u5b57\u6bb5\u63cf\u8ff0\u7b26int\u548c\u5b57\u6bb5\u7684\u540d\u79f0value\uff0c\u4ed6\u4eec\u7684\u5b57\u9762\u91cf\u4e0d\u4f1a\u5b58\u5728\u4e8e\u5e38\u91cf\u6c60\u3002<\/li>\n<\/ul>\n
\u7b26\u53f7\u5f15\u7528\uff1a\u7b26\u53f7\u5f15\u7528\u4e3b\u8981\u8bbe\u6d89\u53ca\u7f16\u8bd1\u539f\u7406\u65b9\u9762\u7684\u6982\u5ff5<\/p>\n
- \n
- \u7c7b\u548c\u63a5\u53e3\u7684\u5168\u9650\u5b9a\u540d\uff0c\u4e5f\u5c31\u662fjava\/lang\/String;\u8fd9\u6837\uff0c\u5c06\u7c7b\u540d\u4e2d\u539f\u6765\u7684”.\u201c\u66ff\u6362\u4e3a\u201d\/”\u5f97\u5230\u7684\uff0c\u4e3b\u8981\u7528\u4e8e\u5728\u8fd0\u884c\u65f6\u89e3\u6790\u5f97\u5230\u7c7b\u7684\u76f4\u63a5\u5f15\u7528<\/li>\n
- \u5b57\u6bb5\u7684\u540d\u79f0\u548c\u63cf\u8ff0\u7b26\uff0c\u5b57\u6bb5\u4e5f\u5c31\u662f\u7c7b\u6216\u8005\u63a5\u53e3\u4e2d\u58f0\u660e\u7684\u53d8\u91cf\uff0c\u5305\u62ec\u7c7b\u7ea7\u522b\u53d8\u91cf\u548c\u5b9e\u4f8b\u7ea7\u7684\u53d8\u91cf<\/li>\n
- \u65b9\u6cd5\u4e2d\u7684\u540d\u79f0\u548c\u63cf\u8ff0\u7b26\uff0c\u4e5f\u5373\u53c2\u6570\u7c7b\u578b+\u8fd4\u56de\u503c<\/li>\n<\/ul>\n
1.1.2 \u8fd0\u884c\u65f6\u5e38\u91cf\u6c60<\/h4>\n
\u5f53Java\u6587\u4ef6\u88ab\u7f16\u8bd1\u6210class\u6587\u4ef6\u4e4b\u540e\uff0c\u4f1a\u751f\u6210\u4e0a\u9762\u7684class\u6587\u4ef6\u5e38\u91cf\u6c60\uff0cJVM\u5728\u6267\u884c\u67d0\u4e2a\u7c7b\u7684\u65f6\u5019\uff0c\u5fc5\u987b\u7ecf\u8fc7\u52a0\u8f7d\u3001\u94fe\u63a5\uff08\u9a8c\u8bc1\u3001\u51c6\u5907\u3001\u89e3\u6790\uff09\u3001\u521d\u59cb\u5316\u7684\u6b65\u9139\uff0c\u8fd0\u884c\u65f6\u5e38\u91cf\u6c60\u5219\u662f\u5728JVM\u5c06\u7c7b\u52a0\u8f7d\u5230\u5185\u5b58\u540e\uff0c\u5c31\u4f1a\u5c06class\u5e38\u91cf\u6c60\u4e2d\u7684\u5185\u5bb9\u5b58\u653e\u5230\u8fd0\u884c\u65f6\u5e38\u91cf\u6c60\u4e2d\uff0c\u4e5f\u5c31\u662fclass\u5e38\u91cf\u6c60\u88ab\u52a0\u8f7d\u5230\u5185\u5b58\u4e4b\u540e\u7684\u7248\u672c\uff0c\u662f\u65b9\u6cd5\u533a\u7684\u4e00\u90e8\u5206\u3002<\/p>\n
\u5728\u89e3\u6790\u9636\u6bb5\uff0c\u4f1a\u628a\u7b26\u53f7\u5f15\u7528\u66ff\u6362\u4e3a\u76f4\u63a5\u5f15\u7528\uff0c\u89e3\u6790\u7684\u8fc7\u7a0b\u4f1a\u53bb\u67e5\u8be2\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\uff0c\u4e5f\u5c31StringTable\uff0c\u4ee5\u4fdd\u8bc1\u8fd0\u884c\u65f6\u5e38\u91cf\u6c60\u6240\u5f15\u7528\u7684\u5b57\u7b26\u4e32\u4e0e\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u4e2d\u662f\u4e00\u81f4\u7684\u3002<\/p>\n
\u8fd0\u884c\u65f6\u5e38\u91cf\u6c60\u76f8\u5bf9\u4e8eclass\u5e38\u91cf\u6c60\u4e00\u5927\u7279\u5f81\u5c31\u662f\u5177\u6709\u52a8\u6001\u6027\uff0cJava\u89c4\u8303\u5e76\u4e0d\u8981\u6c42\u5e38\u91cf\u53ea\u80fd\u5728\u8fd0\u884c\u65f6\u624d\u4ea7\u751f\uff0c\u4e5f\u5c31\u662f\u8bf4\u8fd0\u884c\u65f6\u5e38\u91cf\u6c60\u7684\u5185\u5bb9\u5e76\u4e0d\u5168\u90e8\u6765\u81eaclass\u5e38\u91cf\u6c60\uff0c\u5728\u8fd0\u884c\u65f6\u53ef\u4ee5\u901a\u8fc7\u4ee3\u7801\u751f\u6210\u5e38\u91cf\u5e76\u5c06\u5176\u653e\u5165\u8fd0\u884c\u65f6\u5e38\u91cf\u6c60\u4e2d\uff0c\u8fd9\u79cd\u7279\u6027\u88ab\u7528\u7684\u6700\u591a\u7684\u5c31\u662fString.intern()\u3002<\/p>\n
1.1.3 \u5b57\u7b26\u4e32\u5e38\u91cf\u6c60<\/h4>\n
\u5728JDK6.0\u53ca\u4e4b\u524d\u7248\u672c\uff0c\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u5b58\u653e\u5728\u65b9\u6cd5\u533a\u4e2d\uff0c\u5728JDK7.0\u7248\u672c\u4ee5\u540e\uff0c\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u88ab\u79fb\u5230\u4e86\u5806\u4e2d\u4e86\u3002\u81f3\u4e8e\u4e3a\u4ec0\u4e48\u79fb\u5230\u5806\u5185\uff0c\u5927\u6982\u662f\u7531\u4e8e\u65b9\u6cd5\u533a\u7684\u5185\u5b58\u7a7a\u95f4\u592a\u5c0f\u4e86\u3002\u5728HotSpot VM\u91cc\u5b9e\u73b0\u7684string pool\u529f\u80fd\u7684\u662f\u4e00\u4e2aStringTable\u7c7b\uff0c\u5b83\u662f\u4e00\u4e2aHash\u8868\uff0c\u9ed8\u8ba4\u503c\u5927\u5c0f\u957f\u5ea6\u662f1009\uff1b\u8fd9\u4e2aStringTable\u5728\u6bcf\u4e2aHotSpot VM\u7684\u5b9e\u4f8b\u53ea\u6709\u4e00\u4efd\uff0c\u88ab\u6240\u6709\u7684\u7c7b\u5171\u4eab\u3002\u5b57\u7b26\u4e32\u5e38\u91cf\u7531\u4e00\u4e2a\u4e00\u4e2a\u5b57\u7b26\u7ec4\u6210\uff0c\u653e\u5728\u4e86StringTable\u4e0a\u3002<\/p>\n
\u5728JDK6.0\u4e2d\uff0cStringTable\u7684\u957f\u5ea6\u662f\u56fa\u5b9a\u7684\uff0c\u957f\u5ea6\u5c31\u662f1009\uff0c\u56e0\u6b64\u5982\u679c\u653e\u5165String Pool\u4e2d\u7684String\u975e\u5e38\u591a\uff0c\u5c31\u4f1a\u9020\u6210hash\u51b2\u7a81\uff0c\u5bfc\u81f4\u94fe\u8868\u8fc7\u957f\uff0c\u5f53\u8c03\u7528String#intern()\u65f6\u4f1a\u9700\u8981\u5230\u94fe\u8868\u4e0a\u4e00\u4e2a\u4e00\u4e2a\u627e\uff0c\u4ece\u800c\u5bfc\u81f4\u6027\u80fd\u5927\u5e45\u5ea6\u4e0b\u964d\uff1b\u5728JDK7.0\u4e2d\uff0cStringTable\u7684\u957f\u5ea6\u53ef\u4ee5\u901a\u8fc7\u53c2\u6570\u6307\u5b9a\u3002<\/p>\n
\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u8bbe\u8ba1\u601d\u60f3\uff1a<\/p>\n
- \n
- \u5b57\u7b26\u4e32\u7684\u5206\u914d\uff0c\u548c\u5176\u4ed6\u7684\u5bf9\u8c61\u5206\u914d\u4e00\u6837\uff0c\u8017\u8d39\u9ad8\u6602\u7684\u65f6\u95f4\u4e0e\u7a7a\u95f4\u4ee3\u4ef7\uff0c\u4f5c\u4e3a\u6700\u57fa\u7840\u7684\u6570\u636e\u7c7b\u578b\uff0c\u5927\u91cf\u9891\u7e41\u7684\u521b\u5efa\u5b57\u7b26\u4e32\uff0c\u6781\u5927\u7a0b\u5ea6\u5730\u5f71\u54cd\u7a0b\u5e8f\u7684\u6027\u80fd<\/li>\n
- JVM\u4e3a\u4e86\u63d0\u9ad8\u6027\u80fd\u548c\u51cf\u5c11\u5185\u5b58\u5f00\u9500\uff0c\u5728\u5b9e\u4f8b\u5316\u5b57\u7b26\u4e32\u5e38\u91cf\u7684\u65f6\u5019\u8fdb\u884c\u4e86\u4e00\u4e9b\u4f18\u5316<\/li>\n
- \n
- \n
- \u4e3a\u5b57\u7b26\u4e32\u5f00\u8f9f\u4e00\u4e2a\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\uff0c\u7c7b\u4f3c\u4e8e\u7f13\u5b58\u533a<\/li>\n
- \u521b\u5efa\u5b57\u7b26\u4e32\u5e38\u91cf\u65f6\uff0c\u9996\u5148\u67e5\u770b\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u662f\u5426\u5b58\u5728\u8be5\u5b57\u7b26\u4e32<\/li>\n
- \u5b58\u5728\u8be5\u5b57\u7b26\u4e32\uff0c\u8fd4\u56de\u5f15\u7528\u5b9e\u4f8b\uff0c\u4e0d\u5b58\u5728\uff0c\u5b9e\u4f8b\u5316\u8be5\u5b57\u7b26\u4e32\u5e76\u653e\u5165\u6c60\u4e2d<\/li>\n<\/ul>\n<\/li>\n
- \u5b9e\u73b0\u7684\u57fa\u7840<\/li>\n
- \n
- \n
- \u5b9e\u73b0\u8be5\u4f18\u5316\u7684\u57fa\u7840\u662f\u56e0\u4e3a\u5b57\u7b26\u4e32\u662f\u4e0d\u53ef\u53d8\u7684\uff0c\u53ef\u4ee5\u4e0d\u7528\u62c5\u5fc3\u6570\u636e\u51b2\u7a81\u8fdb\u884c\u5171\u4eab<\/li>\n
- \u8fd0\u884c\u65f6\u5b9e\u4f8b\u521b\u5efa\u7684\u5168\u5c40\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u4e2d\u6709\u4e00\u4e2a\u8868\uff0c\u603b\u662f\u4e3a\u6c60\u4e2d\u6bcf\u4e2a\u552f\u4e00\u7684\u5b57\u7b26\u4e32\u5bf9\u8c61\u7ef4\u62a4\u4e00\u4e2a\u5f15\u7528,\u8fd9\u5c31\u610f\u5473\u7740\u5b83\u4eec\u4e00\u76f4\u5f15\u7528\u7740\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u4e2d\u7684\u5bf9\u8c61\uff0c\u6240\u4ee5\uff0c\u5728\u5e38\u91cf\u6c60\u4e2d\u7684\u8fd9\u4e9b\u5b57\u7b26\u4e32\u4e0d\u4f1a\u88ab\u5783\u573e\u6536\u96c6\u5668\u56de\u6536<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
2. String.intern()\u4e0e\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60<\/strong><\/h2>\n
\/**\n * Returns a canonical representation for the string object.\n * <p>\n * A pool of strings, initially empty, is maintained privately by the\n * class <code>String<\/code>.\n * <p>\n * When the intern method is invoked, if the pool already contains a\n * string equal to this <code>String<\/code> object as determined by\n * the {@link #equals(Object)} method, then the string from the pool is\n * returned. Otherwise, this <code>String<\/code> object is added to the\n * pool and a reference to this <code>String<\/code> object is returned.\n * <p>\n * It follows that for any two strings <code>s<\/code> and <code>t<\/code>,\n * <code>s.intern() == t.intern()<\/code> is <code>true<\/code>\n * if and only if <code>s.equals(t)<\/code> is <code>true<\/code>.\n * <p>\n * All literal strings and string-valued constant expressions are\n * interned. String literals are defined in section 3.10.5 of the\n * <cite>The Java™ Language Specification<\/cite>.\n *\n * @return a string that has the same contents as this string, but is\n * guaranteed to be from a pool of unique strings.\n *\/\npublic native String intern();<\/code><\/pre>\n\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u7684\u4f4d\u7f6e\u4e5f\u662f\u968f\u7740jdk\u7248\u672c\u7684\u4e0d\u540c\u800c\u4f4d\u7f6e\u4e0d\u540c\u3002\u5728jdk6\u4e2d\uff0c\u5e38\u91cf\u6c60\u7684\u4f4d\u7f6e\u5728\u6c38\u4e45\u4ee3\uff08\u65b9\u6cd5\u533a\uff09\u4e2d\uff0c\u6b64\u65f6\u5e38\u91cf\u6c60\u4e2d\u5b58\u50a8\u7684\u662f\u5bf9\u8c61\u3002\u5728jdk7\u4e2d\uff0c\u5e38\u91cf\u6c60\u7684\u4f4d\u7f6e\u5728\u5806\u4e2d\uff0c\u6b64\u65f6\uff0c\u5e38\u91cf\u6c60\u5b58\u50a8\u7684\u5c31\u662f\u5f15\u7528\u4e86\u3002<\/p>\n
\u5728jdk8\u4e2d\uff0c\u6c38\u4e45\u4ee3\uff08\u65b9\u6cd5\u533a\uff09\u88ab\u5143\u7a7a\u95f4\u53d6\u4ee3\u4e86\u3002\u8fd9\u91cc\u5c31\u5f15\u51fa\u4e86\u4e00\u4e2a\u5f88\u5e38\u89c1\u5f88\u7ecf\u5178\u7684\u95ee\u9898\uff0c\u770b\u4e0b\u9762\u8fd9\u6bb5\u4ee3\u7801\u3002<\/p>\n
@Test\npublic void test(){\n String s = new String("2");\n s.intern();\n String s2 = "2";\n System.out.println(s == s2);\n\n String s3 = new String("3") + new String("3");\n s3.intern();\n String s4 = "33";\n System.out.println(s3 == s4);\n}\n\n\/\/jdk6\n\/\/false\n\/\/false\n\n\/\/jdk7\n\/\/false\n\/\/true<\/code><\/pre>\n\u8fd9\u6bb5\u4ee3\u7801\u5728jdk6\u4e2d\u8f93\u51fa\u662ffalse false\uff0c\u4f46\u662f\u5728jdk7\u4e2d\u8f93\u51fa\u7684\u662ffalse true\u3002\u6211\u4eec\u901a\u8fc7\u56fe\u6765\u4e00\u884c\u884c\u89e3\u91ca\u3002<\/p>\n
JDK1.6<\/h3>\n
<\/p>\n
- \n
- String s = new String(“2”);\u521b\u5efa\u4e86\u4e24\u4e2a\u5bf9\u8c61\uff0c\u4e00\u4e2a\u5728\u5806\u4e2d\u7684StringObject\u5bf9\u8c61\uff0c\u4e00\u4e2a\u662f\u5728\u5e38\u91cf\u6c60\u4e2d\u7684\u201c2\u201d\u5bf9\u8c61\u3002<\/li>\n
- s.intern();\u5728\u5e38\u91cf\u6c60\u4e2d\u5bfb\u627e\u4e0es\u53d8\u91cf\u5185\u5bb9\u76f8\u540c\u7684\u5bf9\u8c61\uff0c\u53d1\u73b0\u5df2\u7ecf\u5b58\u5728\u5185\u5bb9\u76f8\u540c\u5bf9\u8c61\u201c2\u201d\uff0c\u8fd4\u56de\u5bf9\u8c612\u7684\u5730\u5740\u3002<\/li>\n
- String s2 = “2”;\u4f7f\u7528\u5b57\u9762\u91cf\u521b\u5efa\uff0c\u5728\u5e38\u91cf\u6c60\u5bfb\u627e\u662f\u5426\u6709\u76f8\u540c\u5185\u5bb9\u7684\u5bf9\u8c61\uff0c\u53d1\u73b0\u6709\uff0c\u8fd4\u56de\u5bf9\u8c61”2″\u7684\u5730\u5740\u3002<\/li>\n
- System.out.println(s == s2);\u4ece\u4e0a\u9762\u53ef\u4ee5\u5206\u6790\u51fa\uff0cs\u53d8\u91cf\u548cs2\u53d8\u91cf\u5730\u5740\u6307\u5411\u7684\u662f\u4e0d\u540c\u7684\u5bf9\u8c61\uff0c\u6240\u4ee5\u8fd4\u56defalse<\/li>\n<\/ul>\n
\n- \n
- String s3 = new String(“3”) + new String(“3”);\u521b\u5efa\u4e86\u4e24\u4e2a\u5bf9\u8c61\uff0c\u4e00\u4e2a\u5728\u5806\u4e2d\u7684StringObject\u5bf9\u8c61\uff0c\u4e00\u4e2a\u662f\u5728\u5e38\u91cf\u6c60\u4e2d\u7684\u201c3\u201d\u5bf9\u8c61\u3002\u4e2d\u95f4\u8fd8\u67092\u4e2a\u533f\u540d\u7684new String(\u201c3\u201d)\u6211\u4eec\u4e0d\u53bb\u8ba8\u8bba\u5b83\u4eec\u3002<\/li>\n
- s3.intern();\u5728\u5e38\u91cf\u6c60\u4e2d\u5bfb\u627e\u4e0es3\u53d8\u91cf\u5185\u5bb9\u76f8\u540c\u7684\u5bf9\u8c61\uff0c\u6ca1\u6709\u53d1\u73b0\u201c33\u201d\u5bf9\u8c61\uff0c\u5728\u5e38\u91cf\u6c60\u4e2d\u521b\u5efa\u201c33\u201d\u5bf9\u8c61\uff0c\u8fd4\u56de\u201c33\u201d\u5bf9\u8c61\u7684\u5730\u5740\u3002<\/li>\n
- String s4 = “33”;\u4f7f\u7528\u5b57\u9762\u91cf\u521b\u5efa\uff0c\u5728\u5e38\u91cf\u6c60\u5bfb\u627e\u662f\u5426\u6709\u76f8\u540c\u5185\u5bb9\u7684\u5bf9\u8c61\uff0c\u53d1\u73b0\u6709\uff0c\u8fd4\u56de\u5bf9\u8c61”33″\u7684\u5730\u5740\u3002<\/li>\n
- System.out.println(s3 == s4);\u4ece\u4e0a\u9762\u53ef\u4ee5\u5206\u6790\u51fa\uff0cs3\u53d8\u91cf\u548cs4\u53d8\u91cf\u5730\u5740\u6307\u5411\u7684\u662f\u4e0d\u540c\u7684\u5bf9\u8c61\uff0c\u6240\u4ee5\u8fd4\u56defalse<\/li>\n<\/ul>\n
JDK1.7<\/h3>\n
<\/p>\n
- \n
- String s = new String(“2”);\u521b\u5efa\u4e86\u4e24\u4e2a\u5bf9\u8c61\uff0c\u4e00\u4e2a\u5728\u5806\u4e2d\u7684StringObject\u5bf9\u8c61\uff0c\u4e00\u4e2a\u662f\u5728\u5806\u4e2d\u7684\u201c2\u201d\u5bf9\u8c61\uff0c\u5e76\u5728\u5e38\u91cf\u6c60\u4e2d\u4fdd\u5b58\u201c2\u201d\u5bf9\u8c61\u7684\u5f15\u7528\u5730\u5740\u3002<\/li>\n
- s.intern();\u5728\u5e38\u91cf\u6c60\u4e2d\u5bfb\u627e\u4e0es\u53d8\u91cf\u5185\u5bb9\u76f8\u540c\u7684\u5bf9\u8c61\uff0c\u53d1\u73b0\u5df2\u7ecf\u5b58\u5728\u5185\u5bb9\u76f8\u540c\u5bf9\u8c61\u201c2\u201d\uff0c\u8fd4\u56de\u5bf9\u8c61\u201c2\u201d\u7684\u5f15\u7528\u5730\u5740\u3002<\/li>\n
- String s2 = “2”;\u4f7f\u7528\u5b57\u9762\u91cf\u521b\u5efa\uff0c\u5728\u5e38\u91cf\u6c60\u5bfb\u627e\u662f\u5426\u6709\u76f8\u540c\u5185\u5bb9\u7684\u5bf9\u8c61\uff0c\u53d1\u73b0\u6709\uff0c\u8fd4\u56de\u5bf9\u8c61\u201c2\u201d\u7684\u5f15\u7528\u5730\u5740\u3002<\/li>\n
- System.out.println(s == s2);\u4ece\u4e0a\u9762\u53ef\u4ee5\u5206\u6790\u51fa\uff0cs\u53d8\u91cf\u548cs2\u53d8\u91cf\u5730\u5740\u6307\u5411\u7684\u662f\u4e0d\u540c\u7684\u5bf9\u8c61\uff0c\u6240\u4ee5\u8fd4\u56defalse<\/li>\n<\/ul>\n
\n- \n
- String s3 = new String(“3”) + new String(“3”);\u521b\u5efa\u4e86\u4e24\u4e2a\u5bf9\u8c61\uff0c\u4e00\u4e2a\u5728\u5806\u4e2d\u7684StringObject\u5bf9\u8c61\uff0c\u4e00\u4e2a\u662f\u5728\u5806\u4e2d\u7684\u201c3\u201d\u5bf9\u8c61\uff0c\u5e76\u5728\u5e38\u91cf\u6c60\u4e2d\u4fdd\u5b58\u201c3\u201d\u5bf9\u8c61\u7684\u5f15\u7528\u5730\u5740\u3002\u4e2d\u95f4\u8fd8\u67092\u4e2a\u533f\u540d\u7684new String(\u201c3\u201d)\u6211\u4eec\u4e0d\u53bb\u8ba8\u8bba\u5b83\u4eec\u3002<\/li>\n
- s3.intern();\u5728\u5e38\u91cf\u6c60\u4e2d\u5bfb\u627e\u4e0es3\u53d8\u91cf\u5185\u5bb9\u76f8\u540c\u7684\u5bf9\u8c61\uff0c\u6ca1\u6709\u53d1\u73b0\u201c33\u201d\u5bf9\u8c61\uff0c\u5c06s3\u5bf9\u5e94\u7684StringObject\u5bf9\u8c61\u7684\u5730\u5740\u4fdd\u5b58\u5230\u5e38\u91cf\u6c60\u4e2d\uff0c\u8fd4\u56deStringObject\u5bf9\u8c61\u7684\u5730\u5740\u3002<\/li>\n
- String s4 = “33”;\u4f7f\u7528\u5b57\u9762\u91cf\u521b\u5efa\uff0c\u5728\u5e38\u91cf\u6c60\u5bfb\u627e\u662f\u5426\u6709\u76f8\u540c\u5185\u5bb9\u7684\u5bf9\u8c61\uff0c\u53d1\u73b0\u6709\uff0c\u8fd4\u56de\u5176\u5730\u5740\uff0c\u4e5f\u5c31\u662fStringObject\u5bf9\u8c61\u7684\u5f15\u7528\u5730\u5740\u3002<\/li>\n
- System.out.println(s3 == s4);\u4ece\u4e0a\u9762\u53ef\u4ee5\u5206\u6790\u51fa\uff0cs3\u53d8\u91cf\u548cs4\u53d8\u91cf\u5730\u5740\u6307\u5411\u7684\u662f\u76f8\u540c\u7684\u5bf9\u8c61\uff0c\u6240\u4ee5\u8fd4\u56detrue\u3002<\/li>\n<\/ul>\n
3. String.intern()\u7684\u5e94\u7528<\/strong><\/h2>\n
\u5728\u5927\u91cf\u5b57\u7b26\u4e32\u8bfb\u53d6\u8d4b\u503c\u7684\u60c5\u51b5\u4e0b\uff0c\u4f7f\u7528String.intern()\u4f1a\u5927\u5927\u7684\u8282\u7701\u5185\u5b58\u7a7a\u95f4\u3002<\/p>\n
static final int MAX = 1000 * 10000;\nstatic final String[] arr = new String[MAX];\n\npublic static void main(String[] args) throws Exception {\n Integer[] DB_DATA = new Integer[10];\n Random random = new Random(10 * 10000);\n for (int i = 0; i < DB_DATA.length; i++) {\n DB_DATA[i] = random.nextInt();\n }\n long t = System.currentTimeMillis();\n for (int i = 0; i < MAX; i++) {\n \/\/arr[i] = new String(String.valueOf(DB_DATA[i % DB_DATA.length]));\n arr[i] = new String(String.valueOf(DB_DATA[i % DB_DATA.length])).intern();\n }\n\n System.out.println((System.currentTimeMillis() - t) + "ms");\n System.gc();\n}<\/code><\/pre>\n\u8fd0\u884c\u7684\u53c2\u6570\u662f\uff1a-Xmx2g -Xms2g -Xmn1500M \u4e0a\u8ff0\u4ee3\u7801\u662f\u4e00\u4e2a\u6f14\u793a\u4ee3\u7801\uff0c\u5176\u4e2d\u6709\u4e24\u6761\u8bed\u53e5\u4e0d\u4e00\u6837\uff0c\u4e00\u6761\u662f\u4f7f\u7528 intern\uff0c\u4e00\u6761\u662f\u672a\u4f7f\u7528 intern\u3002\u53d1\u73b0\u4e0d\u4f7f\u7528 intern \u7684\u4ee3\u7801\u751f\u6210\u4e861000w \u4e2a\u5b57\u7b26\u4e32\uff0c\u5360\u7528\u4e86\u5927\u7ea6640m \u7a7a\u95f4\u3002<\/p>\n
\u4f7f\u7528\u4e86 intern \u7684\u4ee3\u7801\u751f\u6210\u4e861345\u4e2a\u5b57\u7b26\u4e32\uff0c\u5360\u7528\u603b\u7a7a\u95f4 133k \u5de6\u53f3\u3002\u5176\u5b9e\u901a\u8fc7\u89c2\u5bdf\u7a0b\u5e8f\u4e2d\u53ea\u662f\u7528\u5230\u4e8610\u4e2a\u5b57\u7b26\u4e32\uff0c\u6240\u4ee5\u51c6\u786e\u8ba1\u7b97\u540e\u5e94\u8be5\u662f\u6b63\u597d\u76f8\u5dee100w \u500d\u3002\u867d\u7136\u4f8b\u5b50\u6709\u4e9b\u6781\u7aef\uff0c\u4f46\u786e\u5b9e\u80fd\u51c6\u786e\u53cd\u5e94\u51fa intern \u4f7f\u7528\u540e\u4ea7\u751f\u7684\u5de8\u5927\u7a7a\u95f4\u8282\u7701\u3002<\/p>\n
\u5229\u7528String\u7684\u4e0d\u53d8\u6027\uff0cString.intern()\u65b9\u6cd5\u672c\u8d28\u5c31\u662f\u7ef4\u6301\u4e86\u4e00\u4e2aString\u7684\u5e38\u91cf\u6c60\uff0c\u800c\u4e14\u6c60\u91cc\u7684String\u5e94\u8be5\u90fd\u662f\u552f\u4e00\u7684\u3002\u8fd9\u6837\uff0c\u6211\u4eec\u4fbf\u53ef\u4ee5\u5229\u7528\u8fd9\u79cd\u552f\u4e00\u6027\uff0c\u6765\u505a\u4e00\u4e9b\u6587\u7ae0\u4e86\u3002\u6211\u4eec\u53ef\u4ee5\u5229\u7528\u6c60\u91ccString\u7684\u5bf9\u8c61\u6765\u505a\u9501\uff0c\u5b9e\u73b0\u5bf9\u8d44\u6e90\u7684\u63a7\u5236\u3002\u6bd4\u5982\u4e00\u4e2a\u57ce\u5e02\u7684\u67d0\u79cd\u8d44\u6e90\u540c\u4e00\u65f6\u95f4\u53ea\u80fd\u4e00\u4e2a\u7ebf\u7a0b\u8bbf\u95ee\uff0c\u90a3\u5c31\u53ef\u4ee5\u628a\u57ce\u5e02\u540d\u7684String\u5bf9\u8c61\u4f5c\u4e3a\u9501\uff0c\u653e\u5230\u5e38\u91cf\u6c60\u4e2d\u53bb\uff0c\u540c\u4e00\u65f6\u95f4\u53ea\u80fd\u4e00\u4e2a\u7ebf\u7a0b\u83b7\u5f97\u3002<\/p>\n
\u4e0d\u5f53\u7684\u4f7f\u7528\uff1afastjson \u4e2d\u5bf9\u6240\u6709\u7684 json \u7684 key \u4f7f\u7528\u4e86 intern \u65b9\u6cd5\uff0c\u7f13\u5b58\u5230\u4e86\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u4e2d\uff0c\u8fd9\u6837\u6bcf\u6b21\u8bfb\u53d6\u7684\u65f6\u5019\u5c31\u4f1a\u975e\u5e38\u5feb\uff0c\u5927\u5927\u51cf\u5c11\u65f6\u95f4\u548c\u7a7a\u95f4\uff0c\u800c\u4e14 json \u7684 key \u901a\u5e38\u90fd\u662f\u4e0d\u53d8\u7684\u3002\u4f46\u662f\u8fd9\u4e2a\u5730\u65b9\u6ca1\u6709\u8003\u8651\u5230\u5927\u91cf\u7684 json key \u5982\u679c\u662f\u53d8\u5316\u7684\uff0c\u90a3\u5c31\u4f1a\u7ed9\u5b57\u7b26\u4e32\u5e38\u91cf\u6c60\u5e26\u6765\u5f88\u5927\u7684\u8d1f\u62c5\u3002<\/p>\n
\u8fd1\u671f\u70ed\u6587\u63a8\u8350\uff1a<\/strong><\/p>\n
1.1,000+ \u9053 Java\u9762\u8bd5\u9898\u53ca\u7b54\u6848\u6574\u7406(2022\u6700\u65b0\u7248)<\/a><\/p>\n
2.\u52b2\u7206\uff01Java \u534f\u7a0b\u8981\u6765\u4e86\u3002\u3002\u3002<\/a><\/p>\n
3.Spring Boot 2.x \u6559\u7a0b\uff0c\u592a\u5168\u4e86\uff01<\/a><\/p>\n
4.\u522b\u518d\u5199\u6ee1\u5c4f\u7684\u7206\u7206\u7206\u70b8\u7c7b\u4e86\uff0c\u8bd5\u8bd5\u88c5\u9970\u5668\u6a21\u5f0f\uff0c\u8fd9\u624d\u662f\u4f18\u96c5\u7684\u65b9\u5f0f\uff01\uff01<\/a><\/p>\n