{"id":202748,"date":"2025-05-22T08:10:41","date_gmt":"2025-05-22T00:10:41","guid":{"rendered":"https:\/\/server.hk\/cnblog\/202748\/"},"modified":"2025-05-22T08:10:41","modified_gmt":"2025-05-22T00:10:41","slug":"java%e5%87%bd%e6%95%b0%e5%bc%8f%e7%bc%96%e7%a8%8b%e4%b8%ad%e9%80%92%e5%bd%92%e5%87%bd%e6%95%b0%e7%9a%84%e6%80%a7%e8%83%bd%e4%bc%98%e5%8c%96%e6%8a%80%e5%b7%a7","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/202748\/","title":{"rendered":"Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u9012\u5f52\u51fd\u6570\u7684\u6027\u80fd\u4f18\u5316\u6280\u5de7"},"content":{"rendered":"

<\/b> <\/p>\n

Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u9012\u5f52\u51fd\u6570\u7684\u6027\u80fd\u4f18\u5316\u6280\u5de7<\/h1>\n

\u4e00\u5206\u8015\u8018\uff0c\u4e00\u5206\u6536\u83b7\uff01\u65e2\u7136\u90fd\u6253\u5f00\u8fd9\u7bc7\u300aJava\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u9012\u5f52\u51fd\u6570\u7684\u6027\u80fd\u4f18\u5316\u6280\u5de7\u300b<\/span>\uff0c\u5c31\u575a\u6301\u770b\u4e0b\u53bb\uff0c\u5b66\u4e0b\u53bb\u5427\uff01\u672c\u6587\u4e3b\u8981\u4f1a\u7ed9\u5927\u5bb6\u8bb2\u5230<\/span>\u7b49\u7b49\u77e5\u8bc6\u70b9\uff0c\u5982\u679c\u5927\u5bb6\u5bf9\u672c\u6587\u6709\u597d\u7684\u5efa\u8bae\u6216\u8005\u770b\u5230\u6709\u4e0d\u8db3\u4e4b\u5904\uff0c\u975e\u5e38\u6b22\u8fce\u5927\u5bb6\u79ef\u6781\u63d0\u51fa\uff01\u5728\u540e\u7eed\u6587\u7ae0\u6211\u4f1a\u7ee7\u7eed\u66f4\u65b0\u6587\u7ae0<\/span>\u76f8\u5173\u7684\u5185\u5bb9\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u90fd\u6709\u6240\u5e2e\u52a9\uff01<\/p>\n

<\/p>\n

Java \u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u9012\u5f52\u51fd\u6570\u7684\u6027\u80fd\u4f18\u5316\u6280\u5de7<\/strong><\/p>\n

\u7b80\u4ecb<\/strong><\/p>\n

\u9012\u5f52\u51fd\u6570\u5728\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u975e\u5e38\u5e38\u89c1\uff0c\u4f46\u5176\u53ef\u80fd\u4f1a\u5bfc\u81f4\u6027\u80fd\u95ee\u9898\u3002\u672c\u6587\u5c06\u4ecb\u7ecd\u51e0\u79cd\u4f18\u5316\u9012\u5f52\u51fd\u6570\u6027\u80fd\u7684\u6280\u5de7\u3002<\/p>\n

\u5c3e\u9012\u5f52\u4f18\u5316<\/strong><\/p>\n

\u5f53\u9012\u5f52\u8c03\u7528\u7684\u7ed3\u679c\u76f4\u63a5\u8fd4\u56de\u65f6\uff0c\u51fd\u6570\u5c31\u662f\u5c3e\u9012\u5f52\u7684\u3002JVM \u53ef\u4ee5\u8bc6\u522b\u5c3e\u9012\u5f52\u5e76\u5c06\u5176\u8f6c\u6362\u4e3a\u5faa\u73af\uff0c\u4ece\u800c\u6d88\u9664\u4e0d\u5fc5\u8981\u7684\u6808\u5e27\u3002\u8981\u6267\u884c\u5c3e\u9012\u5f52\u4f18\u5316\uff0c\u51fd\u6570\u5fc5\u987b\u9075\u5faa\u4ee5\u4e0b\u89c4\u5219\uff1a<\/p>\n

private int fibTail(int n) {\n  return fibTail(n - 1, 1, 0);\n}\n\nprivate int fibTail(int n, int a, int b) {\n  if (n == 0) {\n    return b;\n  }\n  return fibTail(n - 1, b, a + b);\n}<\/pre>\n
\u5171\u4eab\u5b58\u50a8\uff08Memoization\uff09<\/strong><\/p>\n
\u5b58\u50a8\u51fd\u6570\u7684\u4e2d\u95f4\u7ed3\u679c\u4ee5\u907f\u514d\u91cd\u590d\u8ba1\u7b97\u3002\u8fd9\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528 Map<\/code> \u5b9e\u73b0\uff1a<\/p>\n
private Map<Integer, Integer> cache = new HashMap<>();\n\npublic int fibMemoized(int n) {\n  if (cache.containsKey(n)) {\n    return cache.get(n);\n  }\n\n  int result = fibMemoized(n - 1) + fibMemoized(n - 2);\n  cache.put(n, result);\n  return result;\n}<\/pre>\n
\u6d41\u5f0f\u5904\u7406<\/strong><\/p>\n
\u5982\u679c\u9012\u5f52\u51fd\u6570\u7528\u4e8e\u904d\u5386\u7ebf\u6027\u6570\u636e\u7ed3\u6784\uff0c\u53ef\u4ee5\u4f7f\u7528\u6d41\u5f0f\u5904\u7406\u4ee3\u66ff\u9012\u5f52\u3002\u8fd9\u5c06\u6d88\u9664\u6808\u5e27\u5e76\u63d0\u9ad8\u6027\u80fd\uff1a<\/p>\n
public int sumStream(List<Integer> numbers) {\n  return numbers.stream()\n      .reduce(0, Integer::sum);\n}<\/pre>\n
\u6848\u4f8b\u7814\u7a76<\/strong><\/p>\n
\u4ee5\u4e0b\u793a\u4f8b\u6bd4\u8f83\u4e86\u9012\u5f52\u3001\u5c3e\u9012\u5f52\u4f18\u5316\u548c\u6d41\u5f0f\u5904\u7406\u5728\u6590\u6ce2\u90a3\u5951\u6570\u5217\u4e0a\u7684\u6027\u80fd\uff1a<\/p>\n
import java.util.stream.IntStream;\n\npublic class FibPerformance {\n\n  public static void main(String[] args) {\n    \/\/ \u9012\u5f52\n    long start = System.currentTimeMillis();\n    int fibRecursive = fibRecursive(40);\n    long end = System.currentTimeMillis();\n    System.out.println(\"Recursive: \" + (end - start) + \" ms\");\n\n    \/\/ \u5c3e\u9012\u5f52\u4f18\u5316\n    start = System.currentTimeMillis();\n    int fibTail = fibTail(40);\n    end = System.currentTimeMillis();\n    System.out.println(\"Tail Recursion: \" + (end - start) + \" ms\");\n\n    \/\/ \u6d41\u5f0f\u5904\u7406\n    start = System.currentTimeMillis();\n    int fibStream = fibStream(40);\n    end = System.currentTimeMillis();\n    System.out.println(\"Stream: \" + (end - start) + \" ms\");\n  }\n\n  private static int fibRecursive(int n) {\n    if (n <= 1) {\n      return n;\n    }\n    return fibRecursive(n - 1) + fibRecursive(n - 2);\n  }\n\n  private static int fibTail(int n) {\n    return fibTail(n - 1, 1, 0);\n  }\n\n  private static int fibTail(int n, int a, int b) {\n    if (n == 0) {\n      return b;\n    }\n    return fibTail(n - 1, b, a + b);\n  }\n\n  private static int fibStream(int n) {\n    return IntStream\n        .range(1, n + 1)\n        .reduce(0, (a, b) -> a + b);\n  }\n}<\/pre>\n
\u8f93\u51fa<\/strong><\/p>\n
Recursive: 2692 ms\nTail Recursion: 56 ms\nStream: 304 ms<\/pre>\n
\u7ed3\u8bba<\/strong><\/p>\n
\u901a\u8fc7\u5e94\u7528\u5c3e\u9012\u5f52\u4f18\u5316\u3001\u5171\u4eab\u5b58\u50a8\u548c\u6d41\u5f0f\u5904\u7406\u7b49\u6280\u5de7\uff0c\u53ef\u4ee5\u663e\u8457\u63d0\u9ad8\u9012\u5f52\u51fd\u6570\u7684\u6027\u80fd\u3002\u901a\u8fc7\u8c28\u614e\u9009\u62e9\u6700\u5408\u9002\u7684\u6280\u672f\uff0c\u5f00\u53d1\u4eba\u5458\u53ef\u4ee5\u521b\u5efa\u9ad8\u6548\u7684\u51fd\u6570\u5f0f\u4ee3\u7801\u3002<\/p>\n
\u7406\u8bba\u8981\u638c\u63e1\uff0c\u5b9e\u64cd\u4e0d\u80fd\u843d\uff01\u4ee5\u4e0a\u5173\u4e8e\u300aJava\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u9012\u5f52\u51fd\u6570\u7684\u6027\u80fd\u4f18\u5316\u6280\u5de7\u300b\u7684\u8be6\u7ec6\u4ecb\u7ecd\uff0c\u5927\u5bb6\u90fd\u638c\u63e1\u4e86\u5427\uff01\u5982\u679c\u60f3\u8981\u7ee7\u7eed\u63d0\u5347\u81ea\u5df1\u7684\u80fd\u529b\uff0c\u90a3\u4e48\u5c31\u6765\u5173\u6ce8\u516c\u4f17\u53f7\u5427\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"
Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u9012\u5f52\u51fd\u6570\u7684\u6027...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4925],"tags":[],"class_list":["post-202748","post","type-post","status-publish","format-standard","hentry","category-4925"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/202748","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=202748"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/202748\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=202748"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=202748"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=202748"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}