{"id":10006911,"date":"2022-11-24T17:14:32","date_gmt":"2022-11-24T09:14:32","guid":{"rendered":"https:\/\/ityet.com\/?p=10006911"},"modified":"2022-11-24T17:14:32","modified_gmt":"2022-11-24T09:14:32","slug":"%e5%a6%82%e4%bd%95%e6%ad%a3%e7%a1%ae%e7%9a%84%e5%88%9b%e5%bb%ba%e5%92%8c%e9%94%80%e6%af%81-java-%e5%af%b9%e8%b1%a1%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10006911","title":{"rendered":"\u5982\u4f55\u6b63\u786e\u7684\u521b\u5efa\u548c\u9500\u6bc1 Java \u5bf9\u8c61\uff1f"},"content":{"rendered":"

\u4e00\u3001\u4ecb\u7ecd<\/strong><\/h2>\n

Java\u7531Sun Microsystems\u53d1\u660e\u5e76\u57281995\u5e74\u53d1\u5e03\uff0c\u662f\u4e16\u754c\u4e0a\u4f7f\u7528\u6700\u5e7f\u6cdb\u7684\u7f16\u7a0b\u8bed\u8a00\u4e4b\u4e00\u3002Java\u662f\u4e00\u4e2a\u901a\u7528\u7f16\u7a0b\u8bed\u8a00\u3002\u7531\u4e8e\u5b83\u62e5\u6709\u529f\u80fd\u5f3a\u5927\u7684\u5e93\u3001\u8fd0\u884c\u65f6\u3001\u7b80\u5355\u7684\u8bed\u6cd5\u3001\u5e73\u53f0\u65e0\u5173\uff08Write Once, Run Anywhere – WORA\uff09\u4ee5\u53ca\u4ee4\u4eba\u656c\u754f\u7684\u793e\u533a\u4ece\u800c\u5438\u5f15\u4e86\u5f88\u591a\u7684\u5f00\u53d1\u8005\u3002<\/p>\n

\u672c\u7cfb\u5217\u6587\u7ae0\u6211\u4eec\u6211\u4eec\u5c06\u4f1a\u8986\u76d6\u4e00\u4e9b\u9ad8\u7ea7\u7684Java\u6982\u5ff5\uff0c\u6211\u4eec\u5047\u8bbe\u4f60\u5bf9Java\u8bed\u8a00\u5df2\u7ecf\u6709\u4e00\u4e9b\u57fa\u7840\u77e5\u8bc6\u3002\u672c\u7cfb\u5217\u6587\u7ae0\u5e76\u4e0d\u662f\u4e00\u4e2a\u5b8c\u6574\u7684\u53c2\u8003\uff0c\u800c\u662f\u4e00\u4e2a\u5c06\u60a8\u7684Java\u6280\u80fd\u63d0\u5347\u5230\u4e0b\u4e00\u4e2a\u7ea7\u522b\u7684\u8be6\u7ec6\u6307\u5357\u3002<\/p>\n

\u672c\u7cfb\u5217\u6587\u7ae0\u4e2d\u5c06\u4f1a\u770b\u5230\u4e00\u4e9b\u4ee3\u7801\u7247\u6bb5\uff0c\u5728\u8fd9\u4e9b\u4ee3\u7801\u7247\u6bb5\u91cc\u9762\u5c06\u4f1a\u4f7f\u7528java 7\u7684\u8bed\u6cd5\u4ee5\u53cajava 8\u7684\u8bed\u6cd5\u3002<\/p>\n

\u4e8c\u3001\u5b9e\u4f8b\u6784\u9020\uff08Instance Construction\uff09<\/h2>\n

Java\u662f\u9762\u5411\u5bf9\u8c61\u7684\u7f16\u7a0b\u8bed\u8a00\uff0c\u6240\u4ee5\u65b0\u5b9e\u4f8b\uff08objects\uff09\u7684\u521b\u5efa\u53ef\u80fd\u662f\u5b83\u6700\u91cd\u8981\u7684\u6982\u5ff5\u4e4b\u4e00\u3002\u5728\u65b0\u7684\u7c7b\u5b9e\u4f8b\u4e2d\u6784\u9020\u5668\uff08Constructors\uff09\u626e\u6f14\u4e86\u975e\u5e38\u6838\u5fc3\u7684\u89d2\u8272\uff0cJava\u5bf9\u4e8e\u6784\u9020\u5668\uff08Constructors\uff09\u7684\u5b9a\u4e49\u63d0\u4f9b\u4e86\u5f88\u591a\u65b9\u6848\u3002<\/p>\n

2.1 \u9690\u5f0f\uff08implicitly\uff09\u6784\u9020\u5668<\/h4>\n

Java\u5141\u8bb8\u5b9a\u4e49\u65e0\u4efb\u4f55\u6784\u9020\u5668\u7684\u7c7b\uff0c\u4f46\u662f\u8fd9\u5e76\u4e0d\u610f\u5473\u7740\u6b64\u7c7b\u6ca1\u6709\u6784\u9020\u5668\u3002\u6bd4\u5982\u8bf4\uff0c\u8ba9\u6211\u4eec\u770b\u4e00\u4e0b\u4e0b\u9762\u8fd9\u4e2a\u7c7b\u3002<\/p>\n

package com.javacodegeeks.advanced.construction;\npublic class NoConstructor {\n}<\/code><\/pre>\n
\u6b64\u7c7b\u6ca1\u6709\u6784\u9020\u5668\uff0c\u4f46\u662fJava\u7f16\u8bd1\u5668\u4f1a\u9690\u5f0f\u5730\uff08implicitly\uff09\u751f\u6210\u4e00\u4e2a\u6784\u9020\u5668\u5e76\u4e14\u5728\u4f7f\u7528new\u5173\u952e\u5b57\u521b\u5efa\u65b0\u7684\u7c7b\u5b9e\u4f8b\u65f6\u4f1a\u88ab\u8c03\u7528\u3002<\/p>\n
final NoConstructor noConstructorInstance = new NoConstructor();<\/code><\/pre>\n
2.2 \u65e0\u53c2\u6784\u9020\u5668\uff08Constructors without Arguments\uff09<\/h4>\n
\u65e0\u53c2\u6784\u9020\u5668\u662f\u663e\u5f0f\u6267\u884cJava\u7f16\u8bd1\u5668\u5de5\u4f5c\u7684\u6700\u7b80\u5355\u7684\u65b9\u6cd5\u3002<\/p>\n
package com.javacodegeeks.advanced.construction;\npublic class NoArgConstructor {\n    public NoArgConstructor() {\n        \/\/ Constructor body here\n    }\n}<\/code><\/pre>\n
\u5728\u4f7f\u7528new\u5173\u952e\u5b57\u521b\u5efa\u6b64\u7c7b\u7684\u65b0\u5b9e\u4f8b\u65f6\u4f1a\u6b64\u6784\u9020\u5668\u5c06\u4f1a\u88ab\u8c03\u7528\u3002<\/p>\n
final NoArgConstructor noArgConstructor = new NoArgConstructor();<\/code><\/pre>\n
2.3 \u6709\u53c2\u6784\u9020\u5668\uff08Constructors with Arguments\uff09<\/h4>\n
\u6709\u53c2\u6784\u9020\u5668\u662f\u53c2\u6570\u5316\u521b\u5efa\u7c7b\u5b9e\u4f8b\u7684\u4e00\u4e2a\u975e\u5e38\u6709\u610f\u601d\u548c\u6709\u7528\u7684\u65b9\u6cd5\u3002\u4e0b\u9762\u8fd9\u4e2a\u7c7b\u5b9a\u4e49\u4e86\u4e00\u4e2a\u5177\u6709\u4e24\u4e2a\u53c2\u6570\u7684\u6784\u9020\u5668\u3002<\/p>\n
package com.javacodegeeks.advanced.construction;\npublic class ConstructorWithArguments {\n    public ConstructorWithArguments(final String arg1,final String arg2) {\n        \/\/ Constructor body here\n    }\n}<\/code><\/pre>\n
\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u5f53\u4f7f\u7528new\u5173\u952e\u5b57\u521b\u5efa\u7c7b\u5b9e\u4f8b\u65f6\uff0c\u4e24\u4e2a\u6784\u9020\u53c2\u6570\u90fd\u5fc5\u987b\u63d0\u4f9b\u3002<\/p>\n
final ConstructorWithArguments constructorWithArguments = new ConstructorWithArguments( "arg1", "arg2" );<\/code><\/pre>\n
\u975e\u5e38\u6709\u610f\u601d\u7684\u662f\uff0c\u4f7f\u7528this\u5173\u952e\u5b57\uff0c\u6784\u9020\u5668\u4e4b\u95f4\u53ef\u4ee5\u76f8\u4e92\u8c03\u7528\u3002\u8fd9\u79cd\u8fde\u63a5\u6784\u9020\u51fd\u6570\u7684\u65b9\u5f0f\u5728\u4f5c\u4e3a\u51cf\u5c11\u4ee3\u7801\u91cd\u590d\u65b9\u9762\u662f\u4e00\u4e2a\u975e\u5e38\u597d\u7684\u5b9e\u8df5\uff0c\u5e76\u4e14\u4ece\u8ddf\u672c\u4e0a\u8bf4\u8fd9\u6837\u505a\u53ef\u4ee5\u8ba9\u4e00\u4e2a\u7c7b\u53ea\u6709\u4e00\u4e2a\u521d\u59cb\u5316\u5165\u53e3\u70b9\u3002\u63a5\u4e0a\u4f8b\uff0c\u6211\u4eec\u6dfb\u52a0\u4e00\u4e2a\u53ea\u6709\u4e00\u4e2a\u53c2\u6570\u7684\u6784\u9020\u5668\u3002<\/p>\n
public ConstructorWithArguments(final String arg1) {\nthis(arg1, null);\n}<\/code><\/pre>\n
2.4 \u521d\u59cb\u5316\u5757\uff08Initialization Blocks\uff09<\/h4>\n
Java\u4e5f\u63d0\u4f9b\u4e86\u53e6\u5916\u4e00\u79cd\u4f7f\u7528\u521d\u59cb\u5316\u5757\u7684\u65b9\u5f0f\u5b9e\u73b0\u521d\u59cb\u5316\u903b\u8f91\u3002\u8fd9\u4e2a\u7279\u6027\u5f88\u5c11\u4f7f\u7528\u4f46\u662f\u975e\u5e38\u6709\u5fc5\u8981\u4e86\u89e3\u4e00\u4e0b\u5b83\u7684\u5b58\u5728\u3002<\/p>\n
package com.javacodegeeks.advanced.construction;\n    public class InitializationBlock {\n    {\n        \/\/ initialization code here\n    }\n}<\/code><\/pre>\n
\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u521d\u59cb\u5316\u5757\u53ef\u4ee5\u5f25\u8865\u533f\u540d\u65e0\u53c2\u6784\u9020\u5668\u7684\u7f3a\u9677\u3002\u6709\u4e00\u4e9b\u7279\u6b8a\u7684\u7c7b\u53ef\u80fd\u4f1a\u6709\u5f88\u591a\u4e2a\u521d\u59cb\u5316\u5757\u5e76\u4e14\u4ed6\u4eec\u4f1a\u4f9d\u6b21\u6309\u7167\u4ed6\u4eec\u5728\u4ee3\u7801\u4e2d\u5b9a\u4e49\u7684\u987a\u5e8f\u88ab\u8c03\u7528\uff0c\u6bd4\u5982\uff1a<\/p>\n
package com.javacodegeeks.advanced.construction;\npublic class InitializationBlocks {\n    {\n        \/\/ initialization code here\n    } {\n        \/\/ initialization code here\n    }\n}<\/code><\/pre>\n
\u521d\u59cb\u5316\u5757\u5e76\u4e0d\u662f\u66ff\u4ee3\u6784\u9020\u5668\u5e76\u4e14\u4ed6\u4eec\u53ef\u4ee5\u72ec\u7acb\u4e8e\u6784\u9020\u5668\u800c\u5b58\u5728\u3002\u4f46\u662f\u9700\u8981\u63d0\u53ca\u7684\u6700\u91cd\u8981\u7684\u4e00\u70b9\u5c31\u662f\u521d\u59cb\u5316\u5757\u4f1a\u5728\u4efb\u4f55\u6784\u9020\u5668\u88ab\u8c03\u7528\u4e4b\u524d\u88ab\u6267\u884c\u3002<\/p>\n
package com.javacodegeeks.advanced.construction;\npublic class InitializationBlockAndConstructor {\n    {\n        \/\/ initialization code here\n    }\n    public InitializationBlockAndConstructor() {\n    }\n}<\/code><\/pre>\n
2.5 \u6784\u9020\u4fdd\u969c\uff08Construction guarantee\uff09<\/h4>\n
Java\u63d0\u4f9b\u4e86\u4e00\u4e9b\u5f00\u53d1\u8005\u6240\u4f9d\u8d56\u7684\u521d\u59cb\u5316\u4fdd\u969c\uff0c\u672a\u521d\u59cb\u5316\u7684\u5b9e\u4f8b\u548c\u7c7b\u53c2\u6570\u4f1a\u81ea\u52a8\u521d\u59cb\u5316\u4e3a\u5b83\u4eec\u7684\u9ed8\u8ba4\u503c\u3002<\/p>\n
\"\"<\/p>\n
\u8ba9\u6211\u4eec\u4f7f\u7528\u4e0b\u9762\u7684\u4f8b\u5b50\u6765\u786e\u8ba4\u4e00\u4e0b\u8fd9\u4e9b\u9ed8\u8ba4\u503c\u3002<\/p>\n
package com.javacodegeeks.advanced.construction;\npublic class InitializationWithDefaults {\n    private boolean booleanMember;\n    private byte byteMember;\n    private short shortMember;\n    private int intMember;\n    private long longMember;\n    private char charMember;\n    private float floatMember;\n    private double doubleMember;\n    private Object referenceMember;\n\n    public InitializationWithDefaults() {\n        System.out.println( "booleanMember = " + booleanMember );\n        System.out.println( "byteMember = " + byteMember );\n        System.out.println( "shortMember = " + shortMember );\n        System.out.println( "intMember = " + intMember );\n        System.out.println( "longMember = " + longMember );\n        System.out.println( "charMember = " +\n        Character.codePointAt( new char[] { charMember }, 0 ) );\n        System.out.println( "floatMember = " + floatMember );\n        System.out.println( "doubleMember = " + doubleMember );\n        System.out.println( "referenceMember = " + referenceMember );\n    }\n}<\/code><\/pre>\n
\u4e00\u65e6\u4f7f\u7528new\u5173\u952e\u5b57\u5b9e\u4f8b\u5316\uff1a<\/p>\n
inal InitializationWithDefaults initializationWithDefaults = new InitializationWithDefaults();<\/code><\/pre>\n
\u5c06\u4f1a\u5728\u63a7\u5236\u53f0\u8f93\u51fa\u5982\u4e0b\u7ed3\u679c\uff1a<\/p>\n
booleanMember = false\nbyteMember = 0\nshortMember = 0\nintMember = 0\nlongMember = 0\ncharMember = 0\nfloatMember = 0.0\ndoubleMember = 0.0\nreferenceMember = null<\/code><\/pre>\n
2.6 \u53ef\u89c1\u6027\uff08Visibility\uff09<\/h4>\n
\u6784\u9020\u5668\u53d7Java\u53ef\u89c1\u6027\u89c4\u5219\u7ea6\u675f\u5e76\u4e14\u53ef\u4ee5\u62e5\u6709\u8bbf\u95ee\u63a7\u5236\u4fee\u9970\u7b26\u6765\u51b3\u5b9a\u662f\u5426\u5176\u4ed6\u7c7b\u53ef\u4ee5\u8c03\u7528\u7279\u5b9a\u7684\u6784\u9020\u51fd\u6570\u3002<\/p>\n
\"\"<\/p>\n
2.7 \u5783\u573e\u56de\u6536\uff08Garbage collection\uff09<\/h4>\n
Java\uff08\u7279\u522b\u662fJVM\uff09\u4f7f\u7528\u81ea\u52a8\u5783\u573e\u56de\u6536\u673a\u5236\u3002\u7b80\u800c\u8a00\u4e4b\uff0c\u5f53\u65b0\u5bf9\u8c61\u88ab\u521b\u5efa\uff0cJVM\u5c31\u4f1a\u81ea\u52a8\u4e3a\u8fd9\u4e9b\u65b0\u521b\u5efa\u7684\u5bf9\u8c61\u5206\u914d\u5185\u5b58\u3002\u4e8e\u662f\uff0c\u5f53\u8fd9\u4e9b\u5bf9\u8c61\u6ca1\u6709\u4efb\u4f55\u5f15\u7528\u7684\u65f6\u5019\uff0c\u4ed6\u4eec\u5c31\u4f1a\u88ab\u9500\u6bc1\u5e76\u4e14\u4ed6\u4eec\u6240\u5360\u7528\u7684\u5185\u5b58\u5c31\u4f1a\u88ab\u56de\u6536\u3002<\/p>\n
Java\u5783\u573e\u56de\u6536\u662f\u5206\u4ee3\u7684\uff0c\u57fa\u4e8e\u8fd9\u79cd\u5047\u8bbe\uff08\u5206\u4ee3\u5047\u8bbe\uff09\u5927\u591a\u6570\u7684\u5bf9\u8c61\u5728\u5f88\u5e74\u8f7b\u7684\u65f6\u5019\u5c31\u5df2\u7ecf\u4e0d\u53ef\u8fbe\uff08\u5728\u4ed6\u4eec\u88ab\u521b\u5efa\u4e4b\u540e\u7684\u5f88\u77ed\u7684\u65f6\u95f4\u5185\u5c31\u6ca1\u6709\u4efb\u4f55\u5f15\u7528\u5e76\u4e14\u88ab\u5b89\u5168\u9500\u6bc1\uff09\u3002\u5927\u591a\u6570\u5f00\u53d1\u8005\u66fe\u7ecf\u76f8\u4fe1\u5728Java\u4e2d\u521b\u5efa\u5bf9\u8c61\u662f\u5f88\u6162\u7684\u5e76\u4e14\u5e94\u8be5\u5c3d\u53ef\u80fd\u5730\u907f\u514d\u65b0\u5bf9\u8c61\u7684\u5b9e\u4f8b\u5316\u3002<\/p>\n
\u5b9e\u9645\u4e0a\uff0c\u8fd9\u5e76\u4e0d\u6210\u7acb\uff1a\u5728Java\u4e2d\u521b\u5efa\u5bf9\u8c61\u7684\u5f00\u9500\u975e\u5e38\u7684\u5c0f\u5e76\u4e14\u5f88\u5feb\u3002\u867d\u7136\u5982\u6b64\uff0c\u4f46\u662f\u6ca1\u6709\u5fc5\u8981\u521b\u5efa\u751f\u547d\u5468\u671f\u6bd4\u8f83\u957f\u7684\u5bf9\u8c61\uff0c\u56e0\u4e3a\u521b\u5efa\u8fc7\u591a\u7684\u957f\u5bff\u547d\u5bf9\u8c61\u6700\u7ec8\u53ef\u80fd\u4f1a\u586b\u6ee1\u8001\u5e74\u4ee3\u7a7a\u95f4\u4ece\u800c\u5f15\u53d1stop-the-world\u7684\u5783\u573e\u56de\u6536\uff0c\u8fd9\u6837\u7684\u8bdd\u5f00\u9500\u5c31\u4f1a\u6bd4\u8f83\u5927\u3002<\/p>\n
2.8 \u7ec8\u7ed3\u5668\uff08Finalizers\uff09<\/h4>\n
\u5230\u76ee\u524d\u4e3a\u6b62\uff0c\u6211\u4eec\u5df2\u7ecf\u8c08\u5230\u4e86\u6784\u9020\u51fd\u6570\u548c\u5bf9\u8c61\u521d\u59cb\u5316\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u63d0\u5230\u4efb\u4f55\u5173\u4e8e\u5bf9\u8c61\u9500\u6bc1\u7684\u5185\u5bb9\u3002\u8fd9\u662f\u56e0\u4e3aJava\u4f7f\u7528\u5783\u573e\u6536\u96c6\u5668\u53bb\u7ba1\u7406\u5bf9\u8c61\u7684\u751f\u547d\u5468\u671f\uff0c\u5e76\u4e14\u5783\u573e\u6536\u96c6\u5668\u7684\u8d23\u4efb\u5c31\u662f\u53bb\u9500\u6bc1\u65e0\u7528\u5bf9\u8c61\u5e76\u56de\u6536\u8fd9\u4e9b\u5bf9\u8c61\u5360\u7528\u7684\u5185\u5b58\u3002<\/p>\n
\u7136\u800c\uff0c\u5728Java\u4e2d\u6709\u4e00\u4e2a\u88ab\u79f0\u4e3a\u7ec8\u7ed3\u5668\uff08Finalizers\uff09\u7684\u7279\u6b8a\u7279\u6027\uff0c\u5b83\u6709\u70b9\u7c7b\u4f3c\u4e8e\u6790\u6784\u51fd\u6570\uff0c\u4f46\u662f\u5728\u6267\u884c\u8d44\u6e90\u6e05\u7406\u65f6\u5b83\u6240\u89e3\u51b3\u7684\u662f\u4e0d\u540c\u7684\u610f\u56fe\u3002\u7ec8\u7ed3\u5668\uff08Finalizers\uff09\u662f\u88ab\u8003\u8651\u7528\u6765\u89e3\u51b3\u4e00\u4e9b\u5371\u9669\u7684\u7279\u5f81\uff08\u6bd4\u5982\u4f1a\u5bfc\u81f4\u65e0\u6570\u7684\u526f\u4f5c\u7528\u548c\u6027\u80fd\u95ee\u9898\u7684\u95ee\u9898\uff09\u3002<\/p>\n
\u4e00\u822c\u6765\u8bf4\uff0c\u4ed6\u4eec\u662f\u6ca1\u6709\u5fc5\u8981\u7684\uff0c\u5e94\u8be5\u907f\u514d\uff08\u9664\u4e86\u975e\u5e38\u7f55\u89c1\u7684\u60c5\u51b5\u4e0b\uff0c\u4e3b\u8981\u662f\u6709\u5173\u672c\u5730\u5bf9\u8c61\uff09\u3002Java 7\u8bed\u8a00\u5f15\u5165\u4e86\u4e00\u79cd\u540d\u4e3atry-with-resources\u7684\u66f4\u597d\u7684\u66ff\u4ee3\u65b9\u6cd5\u548cAutoCloseable\u63a5\u53e3\uff0c\u5b83\u5141\u8bb8\u50cf\u5982\u4e0b\u7684\u65b9\u5f0f\u8fd9\u6837\u5e72\u51c0\u7684\u5199\u4ee3\u7801\uff1a<\/p>\n
try ( final InputStream in = Files.newInputStream( path ) ) {\n    \/\/ code here\n}<\/code><\/pre>\n
3\u3001\u9759\u6001\u521d\u59cb\u5316\uff08Static initialization\uff09<\/h2>\n
\u5230\u76ee\u524d\u4e3a\u6b62\uff0c\uff0c\u6211\u4eec\u5df2\u7ecf\u8c08\u5230\u4e86\u6784\u9020\u51fd\u6570\u548c\u5bf9\u8c61\u521d\u59cb\u5316\u3002\u4f46\u662fJava\u4e5f\u652f\u6301\u7c7b\u7ea7\u522b\u7684\u521d\u59cb\u5316\u6784\u9020\uff0c\u6211\u4eec\u79f0\u4e4b\u4e3a\u9759\u6001\u521d\u59cb\u5316\uff08Static initialization\uff09\u3002<\/p>\n
\u9759\u6001\u521d\u59cb\u5316\uff08Static initialization\uff09\u6709\u70b9\u7c7b\u4f3c\u4e8e\u521d\u59cb\u5316\u5757\uff0c\u9664\u4e86\u9700\u8981\u6dfb\u52a0static\u5173\u952e\u5b57\u4e4b\u5916\u3002\u6ce8\u610f\u9759\u6001\u521d\u59cb\u5316\u5728\u6bcf\u6b21\u7c7b\u52a0\u8f7d\u7684\u65f6\u5019\u5b83\u53ea\u6267\u884c\u4e00\u6b21\u3002\u6bd4\u5982\uff1a<\/p>\n
package com.javacodegeeks.advanced.construction;\npublic class StaticInitializationBlock {\n    static {\n        \/\/ static initialization code here\n    }\n}<\/code><\/pre>\n
\u548c\u521d\u59cb\u5316\u5757\u7c7b\u4f3c\uff0c\u5728\u7c7b\u5b9a\u4e49\u65f6\u4f60\u53ef\u4ee5\u5305\u542b\u4efb\u610f\u6570\u91cf\u7684\u521d\u59cb\u5316\u5757\uff0c\u5b83\u4eec\u4f1a\u6839\u636e\u5728\u7c7b\u4ee3\u7801\u4e2d\u51fa\u73b0\u7684\u987a\u5e8f\u4f9d\u6b21\u6267\u884c\uff0c\u6bd4\u5982\uff1a<\/p>\n
package com.javacodegeeks.advanced.construction;\npublic class StaticInitializationBlocks {\n    static {\n        \/\/ static initialization code here\n    }\n    static {\n        \/\/ static initialization code here\n    }\n}<\/code><\/pre>\n
\u56e0\u4e3a\u9759\u6001\u521d\u59cb\u5316\uff08Static initialization\uff09\u5757\u53ef\u4ee5\u4ece\u591a\u4e2a\u5e76\u884c\u7ebf\u7a0b\u4e2d\u89e6\u53d1\uff08\u7b2c\u4e00\u6b21\u7c7b\u52a0\u8f7d\u53d1\u751f\uff09\uff0cJava\u8fd0\u884c\u65f6\u4fdd\u8bc1\u5728\u7ebf\u7a0b\u5b89\u5168\u7684\u524d\u63d0\u4e0b\u4ec5\u4ec5\u88ab\u6267\u884c\u4e00\u6b21\u3002<\/p>\n
4\u3001\u6784\u9020\u6a21\u5f0f\uff08Construction Patterns\uff09<\/h2>\n
\u8fc7\u53bb\u8fd9\u51e0\u5e74\u5f88\u591a\u6613\u4e8e\u7406\u89e3\u548c\u5e7f\u6cdb\u5e94\u7528\u7684\u6784\u9020\u6a21\u5f0f\u5728Java\u793e\u533a\u51fa\u73b0\u3002\u6211\u4eec\u5c06\u4f1a\u4ecb\u7ecd\u51e0\u4e2a\u6bd4\u8f83\u5e38\u7528\u7684\uff1a\u5355\u4f8b\u6a21\u5f0f\uff08singleton\uff09\u3001\u5e2e\u52a9\u5668\uff08helpers\uff09\u3001\u5de5\u5382\u6a21\u5f0f\uff08factory\uff09\u3001\u4f9d\u8d56\u6ce8\u5165\uff08dependency injection \uff09\u2014\u2014\u5927\u5bb6\u719f\u77e5\u7684\u63a7\u5236\u53cd\u8f6c\uff08inversion of control\uff09\u3002<\/p>\n
4.1 \u5355\u4f8b\u6a21\u5f0f\uff08Singleton\uff09<\/h4>\n
\u5355\u4f8b\u6a21\u5f0f\u662f\u8f6f\u4ef6\u5f00\u53d1\u8005\u793e\u533a\u4e2d\u6700\u8001\u4e5f\u662f\u6700\u5177\u4e89\u8bae\u6027\u7684\u6a21\u5f0f\u4e4b\u4e00\u3002\u57fa\u672c\u6765\u8bf4\uff0c\u5b83\u7684\u4e3b\u8981\u601d\u60f3\u5c31\u662f\u786e\u4fdd\u5728\u4efb\u4f55\u65f6\u5019\u7c7b\u4ec5\u4ec5\u53ea\u6709\u4e00\u4e2a\u5b9e\u4f8b\u88ab\u521b\u5efa\u3002\u601d\u60f3\u5c31\u662f\u5982\u6b64\u7b80\u5355\uff0c\u7136\u800c\u5355\u4f8b\u6a21\u5f0f\u5f15\u53d1\u4e86\u5f88\u591a\u5173\u4e8e\u5982\u4f55\u4f7f\u4e4b\u6b63\u786e\u7684\u8ba8\u8bba\uff0c\u7279\u522b\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\u8ba8\u8bba\u3002\u4e0b\u9762\u662f\u5355\u4f8b\u6a21\u5f0f\u539f\u751f\u7248\u672c\u7684\u4f8b\u5b50\uff1a<\/p>\n
package com.javacodegeeks.advanced.construction.patterns;\npublic class NaiveSingleton {\n    private static NaiveSingleton instance;\n\n    private NaiveSingleton() {\n    }\n\n    public static NaiveSingleton getInstance() {\n        if( instance == null ) {\n            instance = new NaiveSingleton();\n        }\n        return instance;\n    }\n}<\/code><\/pre>\n
\u8fd9\u6bb5\u4ee3\u7801\u81f3\u5c11\u6709\u4e00\u4e2a\u95ee\u9898\u5c31\u662f\u5982\u679c\u591a\u4e2a\u7ebf\u7a0b\u540c\u65f6\u8c03\u7528\uff0c\u90a3\u4e48\u6b64\u7c7b\u5c31\u80fd\u591f\u521b\u5efa\u591a\u4e2a\u5b9e\u4f8b\u3002\u8bbe\u8ba1\u5408\u9002\u7684\u5355\u4f8b\u6a21\u5f0f\u7684\u65b9\u6cd5\u4e4b\u4e00\u662f\u4f7f\u7528\u7c7b\u7684 static final\u5c5e\u6027\u3002<\/p>\n
final property of the class.\npackage com.javacodegeeks.advanced.construction.patterns;\npublic class EagerSingleton {\n    private static final EagerSingleton instance = new EagerSingleton();\n\n    private EagerSingleton() {\n    }\n\n    public static EagerSingleton getInstance() {\n        return instance;\n    }\n}<\/code><\/pre>\n
\u5982\u679c\u4f60\u4e0d\u60f3\u6d6a\u8d39\u8d44\u6e90\u5e76\u4e14\u5e0c\u671b\u5728\u5355\u4f8b\u5bf9\u8c61\u771f\u6b63\u9700\u8981\u7684\u65f6\u5019\u624d\u88ab\u5ef6\u8fdf\u521b\u5efa\u7684\u8bdd\uff0c\u8fd9\u5c31\u8981\u6c42\u663e\u793a\u540c\u6b65\u4e86\uff08explicit synchronization\uff09\uff0c\u8fd9\u5c31\u6709\u53ef\u80fd\u5bfc\u81f4\u591a\u7ebf\u7a0b\u73af\u5883\u4e2d\u7684\u5e76\u53d1\u6027\u964d\u4f4e\uff08\u5173\u4e8e\u5e76\u53d1\u7684\u8be6\u7ec6\u5185\u5bb9\u6211\u4eec\u5c06\u4f1a\u5728\u540e\u7eed\u7684\u6587\u7ae0\u4e2d\u8ba8\u8bba\uff09\u3002<\/p>\n
package com.javacodegeeks.advanced.construction.patterns;\npublic class LazySingleton {\nprivate static LazySingleton instance;\n    private LazySingleton() {\n    }\n\n    public static synchronized LazySingleton getInstance() {\n        if( instance == null ) {\n            instance = new LazySingleton();\n        }\n        return instance;\n    }\n}<\/code><\/pre>\n
\u5982\u4eca\uff0c\u5728\u5927\u591a\u6570\u7684\u6848\u4f8b\u4e2d\u5355\u4f8b\u6a21\u5f0f\u5e76\u4e0d\u88ab\u8003\u8651\u4f5c\u4e3a\u4e00\u4e2a\u5f88\u597d\u7684\u9009\u62e9\uff0c\u4e3b\u8981\u662f\u56e0\u4e3a\u5355\u4f8b\u6a21\u5f0f\u5c06\u4f1a\u5bfc\u81f4\u4ee3\u7801\u5f88\u96be\u6d4b\u8bd5\u3002\u4f9d\u8d56\u6ce8\u5165\u6a21\u5f0f\u8ba9\u5355\u4f8b\u6a21\u5f0f\u53d8\u5f97\u6ca1\u6709\u5fc5\u8981\u3002<\/p>\n
4.2 Utility\/Helper\u7c7b<\/h4>\n
utility\u6216\u8005helper\u7c7b\u662f\u88ab\u8bb8\u591a\u5f00\u53d1\u8005\u6240\u4f7f\u7528\u7684\u76f8\u5f53\u6d41\u884c\u7684\u4e00\u79cd\u6a21\u5f0f\u3002\u57fa\u672c\u6765\u8bf4\uff0c\u5b83\u6240\u4ee3\u8868\u7684\u662f\u65e0\u5b9e\u4f8b\uff08 non-instantiable\uff09\u7c7b\uff08\u6784\u9020\u5668\u88ab\u5b9a\u4e49\u6210private\uff09\uff0c\u4ec5\u4ec5\u53ef\u4ee5\u9009\u62e9\u5c06\u65b9\u6cd5\u5b9a\u4e49\u6210final\uff08\u540e\u7eed\u4f1a\u4ecb\u7ecd\u5982\u4f55\u5b9a\u4e49\u7c7b\uff09\u6216\u8005static\u3002\u6bd4\u5982;<\/p>\n
package com.javacodegeeks.advanced.construction.patterns;\npublic final class HelperClass {\n    private HelperClass() {\n    }\n\n    public static void helperMethod1() {\n        \/\/ Method body here\n    }\n\n    public static void helperMethod2() {\n        \/\/ Method body here\n    }\n}<\/code><\/pre>\n
\u7ad9\u5728\u5f00\u53d1\u8005\u7684\u89d2\u5ea6\uff0chelpers\u7c7b\u7ecf\u5e38\u6240\u626e\u6f14\u7684\u662f\u4e00\u4e2a\u5bb9\u5668\u7684\u89d2\u8272\uff0c\u8fd9\u4e2a\u5bb9\u5668\u4e2d\u653e\u4e86\u5f88\u591a\u5728\u5176\u4ed6\u5730\u65b9\u627e\u4e0d\u5230\u4f46\u662f\u5176\u4ed6\u7c7b\u9700\u8981\u76f8\u4e92\u5171\u4eab\u548c\u4f7f\u7528\u7684\u4e92\u76f8\u4e0d\u76f8\u5173\u7684\u65b9\u6cd5\u3002\u8fd9\u79cd\u8bbe\u8ba1\u51b3\u5b9a\u4e86\u5728\u5f88\u591a\u60c5\u51b5\u4e0b\u8981\u907f\u514d\u4f7f\u7528\uff1a\u603b\u80fd\u627e\u5230\u53e6\u4e00\u79cd\u91cd\u7528\u6240\u9700\u529f\u80fd\u7684\u65b9\u5f0f\uff0c\u4fdd\u6301\u4ee3\u7801\u7684\u7b80\u6d01\u548c\u6e05\u6670\u3002<\/p>\n
4.3 \u5de5\u5382\u6a21\u5f0f\uff08Factory\uff09<\/h4>\n
\u5de5\u5382\u6a21\u5f0f\u88ab\u8bc1\u660e\u662f\u8f6f\u4ef6\u5f00\u53d1\u4eba\u5458\u624b\u4e2d\u975e\u5e38\u6709\u7528\u7684\u6280\u672f\u3002\u56e0\u6b64\uff0cJava\u6709\u51e0\u79cd\u98ce\u683c\u5de5\u5382\u6a21\u5f0f\uff0c\u4ece\u5de5\u5382\u65b9\u6cd5\u5230\u62bd\u8c61\u5de5\u5382\u3002\u5de5\u5382\u6a21\u5f0f\u6700\u7b80\u5355\u7684\u4f8b\u5b50\u662f\u8fd4\u56de\u7279\u5b9a\u7c7b\u7684\u65b0\u5b9e\u4f8b\u7684\u9759\u6001\u65b9\u6cd5\uff08\u5de5\u5382\u65b9\u6cd5\uff09\u3002\u4f8b\u5982\uff1a<\/p>\n
package com.javacodegeeks.advanced.construction.patterns;\npublic class Book {\n    private Book( final String title) {\n    }\n    public static Book newBook( final String title ) {\n        return new Book( title );\n    }\n}<\/code><\/pre>\n
\u6709\u4eba\u53ef\u80fd\u4f1a\u4e89\u8fa9\u8bf4\uff0c\u4ecb\u7ecdnewBook\u5de5\u5382\u65b9\u6cd5\u5e76\u6ca1\u6709\u4ec0\u4e48\u610f\u4e49\uff0c\u4f46\u662f\u4f7f\u7528\u8fd9\u79cd\u6a21\u5f0f\u901a\u5e38\u4f1a\u4f7f\u4ee3\u7801\u66f4\u5177\u53ef\u8bfb\u6027\u3002\u5de5\u5382\u6a21\u5f0f\u7684\u53e6\u4e00\u4e2a\u53d8\u5316\u6d89\u53ca\u63a5\u53e3\u6216\u62bd\u8c61\u7c7b\uff08\u62bd\u8c61\u5de5\u5382\uff09\u3002\u4f8b\u5982\uff0c\u8ba9\u6211\u4eec\u5b9a\u4e49\u4e00\u4e2a\u5de5\u5382\u63a5\u53e3\uff1a<\/p>\n
public interface BookFactory {\n    Book newBook();\n}<\/code><\/pre>\n
\u4f9d\u8d56\u5e93\u7c7b\u578b\uff0c\u5b8c\u6210\u51e0\u79cd\u4e0d\u540c\u7684\u5b9e\u73b0\uff1a<\/p>\n
public class Library implements BookFactory {\n    @Override\n    public Book newBook() {\n        return new PaperBook();\n    }\n}\n\npublic class KindleLibrary implements BookFactory {\n@Override\n    public Book newBook() {\n        return new KindleBook();\n    }\n}<\/code><\/pre>\n
\u73b0\u5728\uff0cBook\u7684\u7279\u5b9a\u7c7b\u88ab\u9690\u85cf\u5728BookFactory\u63a5\u53e3\u5b9e\u73b0\u4e4b\u540e\uff0cBookFactory\u4ecd\u7136\u63d0\u4f9b\u521b\u5efabook\u7684\u901a\u7528\u65b9\u5f0f\u3002<\/p>\n
4.4 \u4f9d\u8d56\u6ce8\u5165\uff08Dependency Injection\uff09<\/h4>\n
\u4f9d\u8d56\u6ce8\u5165\uff08\u4e00\u8bf4\u63a7\u5236\u53cd\u8f6c\uff09\u88ab\u7c7b\u8bbe\u8ba1\u8005\u8ba4\u4e3a\u662f\u4e00\u4e2a\u5f88\u597d\u7684\u505a\u6cd5\uff1a\u5982\u679c\u67d0\u4e9b\u7c7b\u7684\u5b9e\u4f8b\u4f9d\u8d56\u5176\u4ed6\u7c7b\u7684\u5b9e\u4f8b\uff0c\u88ab\u4f9d\u8d56\u7684\u5b9e\u4f8b\u5e94\u8be5\u901a\u8fc7\u6784\u9020\uff08\u6bd4\u5982\u901a\u8fc7\u8bbe\u7f6e\u5668\u2014\u2014setters\uff0c\u6216\u8005\u7b56\u7565\u2014\u2014strategies\u6a21\u5f0f\u7b49\uff09\u7684\u601d\u60f3\u63d0\u4f9b\u7ed9\u4f9d\u8d56\u7684\u5b9e\u4f8b\uff0c\u800c\u4e0d\u662f\u4f9d\u8d56\u7684\u5b9e\u4f8b\u81ea\u884c\u521b\u5efa\u3002\u770b\u4e00\u4e0b\u4e0b\u9762\u8fd9\u79cd\u60c5\u51b5\uff1a<\/p>\n
package com.javacodegeeks.advanced.construction.patterns;\nimport java.text.DateFormat;\nimport java.util.Date;\npublic class Dependant {\n    private final DateFormat format = DateFormat.getDateInstance();\n\n    public String format( final Date date ) {\n        return format.format( date );\n    }\n}<\/code><\/pre>\n
\u7c7bDependant\u9700\u8981\u4e00\u4e2aDateFormat\u7684\u5b9e\u4f8b\uff0c\u5e76\u4e14\u5b83\u4ec5\u4ec5\u53ea\u662f\u5728\u6784\u9020\u65f6\u901a\u8fc7\u8c03\u7528DateFormat.getDateInstance() \u521b\u5efa\u3002\u6700\u597d\u7684\u8bbe\u8ba1\u65b9\u6848\u5e94\u8be5\u662f\u901a\u8fc7\u6784\u9020\u5668\u53c2\u6570\u7684\u5f62\u5f0f\u53bb\u5b8c\u6210\u76f8\u540c\u7684\u4e8b\u60c5\u3002<\/p>\n
package com.javacodegeeks.advanced.construction.patterns;\nimport java.text.DateFormat;\nimport java.util.Date;\npublic class Dependant {\n    private final DateFormat format;\n\n    public Dependant( final DateFormat format ) {\n        this.format = format;\n    }\n\n\n    public String format( final Date date ) {\n        return format.format( date );\n    }\n}<\/code><\/pre>\n
\u6309\u8fd9\u79cd\u65b9\u6848\u5b9e\u73b0\u7684\u8bdd\uff0c\u7c7b\u7684\u6240\u6709\u4f9d\u8d56\u90fd\u662f\u901a\u8fc7\u5916\u90e8\u63d0\u4f9b\uff0c\u8fd9\u6837\u5c31\u5f88\u5bb9\u6613\u7684\u4fee\u6539date format\u548c\u4e3a\u7c7b\u5199\u6d4b\u8bd5\u7528\u4f8b\u3002<\/p>\n
\u5728\u672c\u7cfb\u5217\u6587\u7ae0\u7684\u8fd9\u4e00\u90e8\u5206\u4e2d\uff0c\u6211\u4eec\u4e00\u76f4\u5728\u7814\u7a76\u7c7b\u548c\u7c7b\u7684\u5b9e\u4f8b\u6784\u9020\u4ee5\u53ca\u521d\u59cb\u5316\u6280\u672f\uff0c\u6db5\u76d6\u4e86\u51e0\u79cd\u5e7f\u6cdb\u4f7f\u7528\u7684\u6a21\u5f0f\u3002\u5728\u4e0b\u4e00\u90e8\u5206\u4e2d\uff0c\u6211\u4eec\u5c06\u5206\u6790Object\u7c7b\u4ee5\u53ca\u5176\u719f\u77e5\u65b9\u6cd5\u7684\u7528\u6cd5\uff1aequals\uff0chashCode\uff0ctoString\u548cclone\u3002<\/p>\n
\u539f\u6587\u94fe\u63a5\uff1ahttps:\/\/blog.csdn.net\/zyhlwzy…<\/a><\/p>\n
\u7248\u6743\u58f0\u660e\uff1a\u672c\u6587\u4e3aCSDN\u535a\u4e3b\u300cRonTech\u300d\u7684\u539f\u521b\u6587\u7ae0\uff0c\u9075\u5faaCC 4.0 BY-SA\u7248\u6743\u534f\u8bae\uff0c\u8f6c\u8f7d\u8bf7\u9644\u4e0a\u539f\u6587\u51fa\u5904\u94fe\u63a5\u53ca\u672c\u58f0\u660e\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
5.\u300aJava\u5f00\u53d1\u624b\u518c\uff08\u5d69\u5c71\u7248\uff09\u300b\u6700\u65b0\u53d1\u5e03\uff0c\u901f\u901f\u4e0b\u8f7d\uff01<\/a><\/p>\n
\u89c9\u5f97\u4e0d\u9519\uff0c\u522b\u5fd8\u4e86\u968f\u624b\u70b9\u8d5e+\u8f6c\u53d1\u54e6\uff01<\/p>\n
https:\/\/segmentfault.com\/a\/1190000042888119<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e00\u3001\u4ecb\u7ecd Java\u7531Sun Microsystems\u53d1\u660e\u5e76\u57281995\u5e74\u53d1\u5e03\uff0c\u662f\u4e16\u754c\u4e0a\u4f7f\u7528\u6700\u5e7f\u6cdb\u7684\u7f16\u7a0b\u8bed\u8a00\u4e4b\u4e00\u3002 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10006911","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006911","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10006911"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006911\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10006911"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10006911"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10006911"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}