\u4e00\u3001Stream\u7b80\u4ecb
\n1\u3001\u4ec0\u4e48\u662fStream?
\nJava8 \u4e2d\uff0cCollection \u65b0\u589e\u4e86\u4e24\u4e2a\u6d41\u65b9\u6cd5\uff0c\u5206\u522b\u662f Stream() \u548c parallelStream()<\/p>\n
Java8 \u4e2d\u6dfb\u52a0\u4e86\u4e00\u4e2a\u65b0\u7684\u63a5\u53e3\u7c7b Stream\uff0c\u76f8\u5f53\u4e8e\u9ad8\u7ea7\u7248\u7684 Iterator\uff0c\u5b83\u53ef\u4ee5\u901a\u8fc7 Lambda \u8868\u8fbe\u5f0f\u5bf9\u96c6\u5408\u8fdb\u884c\u5927\u6279\u91cf\u6570\u636e\u64cd\u4f5c\uff0c\u6216 \u8005\u5404\u79cd\u975e\u5e38\u4fbf\u5229\u3001\u9ad8\u6548\u7684\u805a\u5408\u6570\u636e\u64cd\u4f5c\u3002<\/p>\n
2\u3001\u4e3a\u4ec0\u4e48\u8981\u4f7f\u7528Stream?
\n\u5728 Java8 \u4e4b\u524d\uff0c\u6211\u4eec\u901a\u5e38\u662f\u901a\u8fc7 for \u5faa\u73af\u6216\u8005 Iterator \u8fed\u4ee3\u6765\u91cd\u65b0\u6392\u5e8f\u5408\u5e76\u6570\u636e\uff0c\u53c8\u6216\u8005\u901a\u8fc7\u91cd\u65b0\u5b9a\u4e49 Collections.sorts \u7684 Comparator \u65b9\u6cd5\u6765\u5b9e\u73b0\uff0c\u8fd9\u4e24\u79cd\u65b9\u5f0f\u5bf9\u4e8e\u5927\u6570\u636e\u91cf\u7cfb\u7edf\u6765\u8bf4\uff0c\u6548\u7387\u5e76\u4e0d\u662f\u5f88\u7406\u60f3\u3002Stream \u7684\u805a\u5408\u64cd\u4f5c\u4e0e\u6570\u636e\u5e93 SQL \u7684\u805a\u5408\u64cd\u4f5c sorted\u3001filter\u3001map \u7b49\u7c7b\u4f3c\u3002\u6211\u4eec\u5728\u5e94\u7528\u5c42\u5c31\u53ef\u4ee5\u9ad8\u6548\u5730\u5b9e\u73b0\u7c7b\u4f3c\u6570\u636e\u5e93 SQL \u7684 \u805a\u5408\u64cd\u4f5c\u4e86\uff0c\u800c\u5728\u6570\u636e\u64cd\u4f5c\u65b9\u9762\uff0cStream \u4e0d\u4ec5\u53ef\u4ee5\u901a\u8fc7\u4e32\u884c\u7684\u65b9\u5f0f\u5b9e\u73b0\u6570\u636e\u64cd\u4f5c\uff0c\u8fd8\u53ef\u4ee5\u901a\u8fc7\u5e76\u884c\u7684\u65b9\u5f0f\u5904\u7406\u5927\u6279\u91cf\u6570\u636e\uff0c\u63d0\u9ad8\u6570\u636e \u7684\u5904\u7406\u6548\u7387\u3002<\/p>\n
\u4e8c\u3001Stream\u4f7f\u7528
\n1\u3001Stream\u64cd\u4f5c\u5206\u7c7b
\n\u5b98\u65b9\u5c06 Stream \u4e2d\u7684\u64cd\u4f5c\u5206\u4e3a\u4e24\u5927\u7c7b\uff1a\u7ec8\u7ed3\u64cd\u4f5c\uff08Terminal operations\uff09\u548c\u4e2d\u95f4\u64cd\u4f5c\uff08Intermediate operations\uff09\u3002<\/p>\n
\u4e2d\u95f4\u64cd\u4f5c\u4f1a\u8fd4\u56de\u4e00\u4e2a\u65b0\u7684\u6d41\uff0c\u4e00\u4e2a\u6d41\u53ef\u4ee5\u540e\u9762\u8ddf\u968f\u96f6\u4e2a\u6216\u591a\u4e2a\u4e2d\u95f4\u64cd\u4f5c\u3002\u5176\u76ee\u7684\u4e3b\u8981\u662f\u6253\u5f00\u6d41\uff0c\u505a\u51fa\u67d0\u79cd\u7a0b\u5ea6\u7684\u6570\u636e\u6620\u5c04\/\u8fc7\u6ee4\uff0c\u7136\u540e\u4f1a\u8fd4\u56de\u4e00\u4e2a\u65b0\u7684\u6d41\uff0c\u4ea4\u7ed9\u4e0b\u4e00\u4e2a\u64cd\u4f5c\u4f7f\u7528\u3002\u8fd9\u7c7b\u64cd\u4f5c\u90fd\u662f\u60f0\u6027\u5316\u7684\uff08lazy\uff09\uff0c\u5c31\u662f\u8bf4\uff0c\u4ec5\u4ec5\u8c03\u7528\u5230\u8fd9\u7c7b\u65b9\u6cd5\uff0c\u5e76\u6ca1\u6709\u771f\u6b63\u5f00\u59cb\u6d41\u7684\u904d\u5386\u3002\u800c\u662f\u5728\u7ec8\u7ed3\u64cd\u4f5c\u5f00\u59cb\u7684\u65f6\u5019\u624d\u771f\u6b63\u5f00\u59cb\u6267\u884c\u3002<\/p>\n
\u4e2d\u95f4\u64cd\u4f5c\u53c8\u53ef\u4ee5\u5206\u4e3a\u65e0\u72b6\u6001\uff08Stateless\uff09\u4e0e\u6709\u72b6\u6001\uff08Stateful\uff09\u64cd\u4f5c:<\/p>\n
\u65e0\u72b6\u6001\u662f\u6307\u5143\u7d20\u7684\u5904\u7406\u4e0d\u53d7\u4e4b\u524d\u5143\u7d20\u7684\u5f71\u54cd\uff1b
\n\u6709\u72b6\u6001\u662f\u6307\u8be5\u64cd\u4f5c\u53ea\u6709\u62ff\u5230\u6240\u6709\u5143\u7d20\u4e4b\u540e\u624d\u80fd\u7ee7\u7eed\u4e0b\u53bb\u3002
\n\u7ec8\u7ed3\u64cd\u4f5c\u662f\u6307\u8fd4\u56de\u6700\u7ec8\u7684\u7ed3\u679c\u3002\u4e00\u4e2a\u6d41\u53ea\u80fd\u6709\u4e00\u4e2a\u7ec8\u7ed3\u64cd\u4f5c\uff0c\u5f53\u8fd9\u4e2a\u64cd\u4f5c\u6267\u884c\u540e\uff0c\u8fd9\u4e2a\u6d41\u5c31\u88ab\u4f7f\u7528\u201c\u5149\u201d\u4e86\uff0c\u65e0\u6cd5\u518d\u88ab\u64cd\u4f5c\u3002\u6240\u4ee5\u8fd9\u5fc5\u5b9a\u8fd9\u4e2a\u6d41\u7684\u6700\u540e\u4e00\u4e2a\u64cd\u4f5c\u3002\u7ec8\u7ed3\u64cd\u4f5c\u7684\u6267\u884c\u624d\u4f1a\u771f\u6b63\u5f00\u59cb\u6d41\u7684\u904d\u5386\uff0c\u5e76\u4e14\u4f1a\u751f\u6210\u4e00\u4e2a\u7ed3\u679c\u3002<\/p>\n
\u7ec8\u7ed3\u64cd\u4f5c\u53c8\u53ef\u4ee5\u5206\u4e3a\u77ed\u8def\uff08Short-circuiting\uff09\u4e0e\u975e\u77ed\u8def\uff08Unshort-circuiting\uff09\u64cd\u4f5c\uff0c<\/p>\n
\u77ed\u8def\u662f\u6307\u9047\u5230\u67d0\u4e9b\u7b26\u5408\u6761\u4ef6\u7684\u5143\u7d20\u5c31\u53ef\u4ee5\u5f97\u5230\u6700\u7ec8\u7ed3\u679c\uff0c
\n\u975e\u77ed\u8def\u662f\u6307\u5fc5\u987b\u5904\u7406\u5b8c\u6240\u6709\u5143\u7d20\u624d\u80fd\u5f97\u5230\u6700\u7ec8\u7ed3\u679c\u3002\u64cd\u4f5c\u5206\u7c7b\u8be6\u60c5\u5982\u4e0b\u56fe\u6240\u793a\uff1a<\/p>\n
2.Steam\u6d41\u5e38\u7528\u65b9\u6cd5<\/p>\n
\u4e09\u3001Stream\u6027\u80fd
\n1\u3001\u6027\u80fd\u5206\u6790
\n\u5728\u5c11\u6570\u636e\u91cf\u7684\u5904\u7406\u573a\u666f\u4e2d\uff08size <= 1000\uff09
\nstream \u7684\u5904\u7406\u6548\u7387\u662f\u4e0d\u5982\u4f20\u7edf\u7684 iterator \u5916\u90e8\u8fed\u4ee3\u5668\u5904\u7406\u901f\u5ea6\u5feb\u7684\uff0c\u4f46\u662f\u5b9e\u9645\u4e0a\u8fd9\u4e9b\u5904\u7406\u4efb\u52a1\u672c\u8eab\u8fd0\u884c\u65f6\u95f4\u90fd\u4f4e\u4e8e\u6beb\u79d2\uff0c\u8fd9\u70b9\u6548\u7387\u7684\u5dee\u8ddd\u5bf9\u666e\u901a\u4e1a\u52a1\u51e0\u4e4e\u6ca1\u6709\u5f71\u54cd\uff0c\u53cd\u800c stream \u53ef\u4ee5\u4f7f\u5f97\u4ee3\u7801\u66f4\u52a0\u7b80\u6d01\uff1b<\/p>\n
\u5728\u5927\u91cf\u6570\u636e\uff08size > 10000\uff09
\nstream \u7684\u5904\u7406\u6548\u7387\u4f1a\u9ad8\u4e8e iterator\uff0c\u7279\u522b\u662f\u4f7f\u7528\u4e86\u5e76\u884c\u6d41\uff0c\u5728 cpu \u6070\u597d\u5c06\u7ebf\u7a0b\u5206\u914d\u5230\u591a\u4e2a\u6838\u5fc3\u7684\u6761\u4ef6\u4e0b\uff08\u5f53\u7136 parallel stream \u5e95\u5c42\u4f7f\u7528\u7684\u662f JVM \u7684 ForkJoinPool\uff0c\u8fd9\u4e1c\u897f\u5206\u914d\u7ebf\u7a0b\u672c\u8eab\u5c31\u5f88\u7384\u5b66\uff09\uff0c\u53ef\u4ee5\u8fbe\u5230\u4e00\u4e2a\u5f88\u9ad8\u7684\u8fd0\u884c\u6548\u7387\uff0c\u7136\u800c\u5b9e\u9645\u666e\u901a\u4e1a\u52a1\u4e00\u822c\u4e0d\u4f1a\u6709\u9700\u8981\u8fed\u4ee3\u9ad8\u4e8e 10000 \u6b21\u7684\u8ba1\u7b97\uff1b<\/p>\n
Parallel Stream \uff08\u5e76\u884c\u6d41\uff09
\nParallel Stream \u53d7\u5f15 CPU \u73af\u5883\u5f71\u54cd\u5f88\u5927\uff0c\u5f53\u6ca1\u5206\u914d\u5230\u591a\u4e2a cpu \u6838\u5fc3\u65f6\uff0c\u52a0\u4e0a\u5f15\u7528 forkJoinPool \u7684\u5f00\u9500\uff0c\u8fd0\u884c\u6548\u7387\u53ef\u80fd\u8fd8\u4e0d\u5982\u666e\u901a\u7684 Stream\uff1b<\/p>\n
2\u3001\u4f7f\u7528\u5efa\u8bae
\n\u7b80\u5355\u7684\u8fed\u4ee3\u903b\u8f91\uff0c\u53ef\u4ee5\u76f4\u63a5\u4f7f\u7528 iterator\uff0c\u5bf9\u4e8e\u6709\u591a\u6b65\u5904\u7406\u7684\u8fed\u4ee3\u903b\u8f91\uff0c\u53ef\u4ee5\u4f7f\u7528 stream\uff0c\u635f\u5931\u4e00\u70b9\u51e0\u4e4e\u6ca1\u6709\u7684\u6548\u7387\uff0c\u6362\u6765\u4ee3\u7801\u7684\u9ad8\u53ef\u8bfb\u6027\u662f\u503c\u5f97\u7684\uff1b<\/p>\n
\u5355\u6838 cpu \u73af\u5883\uff0c\u4e0d\u63a8\u8350\u4f7f\u7528 parallel stream\uff0c\u5728\u591a\u6838 cpu \u4e14\u6709\u5927\u6570\u636e\u91cf\u7684\u6761\u4ef6\u4e0b\uff0c\u63a8\u8350\u4f7f\u7528 paralle stream\uff1b<\/p>\n
stream \u4e2d\u542b\u6709\u88c5\u7bb1\u7c7b\u578b\uff0c\u5728\u8fdb\u884c\u4e2d\u95f4\u64cd\u4f5c\u4e4b\u524d\uff0c\u6700\u597d\u8f6c\u6210\u5bf9\u5e94\u7684\u6570\u503c\u6d41\uff0c\u51cf\u5c11\u7531\u4e8e\u9891\u7e41\u7684\u62c6\u7bb1\u3001\u88c5\u7bb1\u9020\u6210\u7684\u6027\u80fd\u635f\u5931\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e00\u3001Stream\u7b80\u4ecb 1\u3001\u4ec0\u4e48\u662f...<\/p>\n","protected":false},"author":1,"featured_media":621,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[11],"class_list":["post-43","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-22","tag-11"],"_links":{"self":[{"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=\/wp\/v2\/posts\/43","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=43"}],"version-history":[{"count":1,"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=\/wp\/v2\/posts\/43\/revisions"}],"predecessor-version":[{"id":45,"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=\/wp\/v2\/posts\/43\/revisions\/45"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=\/wp\/v2\/media\/621"}],"wp:attachment":[{"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=43"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=43"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.licaneku.fun\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=43"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}