{"id":645,"date":"2022-09-26T16:51:12","date_gmt":"2022-09-26T08:51:12","guid":{"rendered":"https:\/\/22pig.com\/?p=645"},"modified":"2022-09-26T16:51:12","modified_gmt":"2022-09-26T08:51:12","slug":"java%e9%ab%98%e6%95%88%e8%af%bb%e5%8f%96%e5%a4%a7%e6%96%87%e4%bb%b6","status":"publish","type":"post","link":"http:\/\/22pig.com\/?p=645","title":{"rendered":"java\u9ad8\u6548\u8bfb\u53d6\u5927\u6587\u4ef6"},"content":{"rendered":"<pre class=\"has-pre-numbering\"><code class=\"language-\"><\/code><\/pre>\n<p><strong>BufferReader<\/strong><\/p>\n<pre class=\"has-pre-numbering\"><code class=\"language-\"><\/code><\/pre>\n<p>\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528 BufferReader#readLine \u9010\u884c\u8bfb\u53d6\u6570\u636e\u3002<code class=\"language-\"><\/p>\n<p><\/code><\/p>\n<pre class=\"has-pre-numbering\"><code class=\"language-\">try\u00a0(BufferedReader\u00a0fileBufferReader\u00a0=\u00a0new\u00a0BufferedReader(new\u00a0FileReader(<span class=\"string\">\"temp\/test.txt\"<\/span>)))\u00a0{\u00a0\n\u00a0\u00a0\u00a0\u00a0String\u00a0fileLineContent;\u00a0\n\u00a0\u00a0\u00a0\u00a0while\u00a0((fileLineContent\u00a0=\u00a0fileBufferReader.readLine())\u00a0!=\u00a0<span class=\"op\">null<\/span>)\u00a0{\u00a0\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0process\u00a0the\u00a0line.\u00a0\n\u00a0\u00a0\u00a0\u00a0}\u00a0\n}\u00a0catch\u00a0(FileNotFoundException\u00a0e)\u00a0{\u00a0\n\u00a0\u00a0\u00a0\u00a0e.printStackTrace();\u00a0\n}\u00a0catch\u00a0(IOException\u00a0e)\u00a0{\u00a0\n\u00a0\u00a0\u00a0\u00a0e.printStackTrace();\u00a0\n}\u00a0<\/code>\n\n\n\n<\/pre>\n<p><strong>Apache Commons IOCommon-IO<\/strong><\/p>\n<p>\u4e2d\u6709\u4e00\u4e2a\u65b9\u6cd5 FileUtils#lineIterator\u53ef\u4ee5\u5b9e\u73b0\u9010\u884c\u8bfb\u53d6\u65b9\u5f0f,\u4f7f\u7528\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<p>&nbsp;<\/p>\n<pre class=\"has-pre-numbering\"><code class=\"language-\">Stopwatch\u00a0stopwatch\u00a0=\u00a0Stopwatch.createStarted();\u00a0\nLineIterator\u00a0fileContents\u00a0=\u00a0FileUtils.lineIterator(new\u00a0File(<span class=\"string\">\"temp\/test.txt\"<\/span>),\u00a0StandardCharsets.UTF_8.<span class=\"keyword\">name<\/span>());\u00a0\nwhile\u00a0(fileContents.hasNext())\u00a0{\u00a0\n\u00a0\u00a0\u00a0\u00a0fileContents.nextLine();\u00a0\n\u00a0\u00a0\u00a0\u00a0\/\/\u00a0\u00a0pass\u00a0\n}\u00a0\nlogMemory();\u00a0\nfileContents.<span class=\"keyword\">close<\/span>();\u00a0\nstopwatch.stop();\u00a0\nSystem.<span class=\"keyword\">out<\/span>.println(<span class=\"string\">\"read\u00a0all\u00a0lines\u00a0spend\u00a0\"<\/span>\u00a0+\u00a0stopwatch.elapsed(TimeUnit.SECONDS)\u00a0+\u00a0<span class=\"string\">\"\u00a0s\"<\/span>);<\/code>\n\n\n\n<\/pre>\n<p><strong>Java8 stream<\/strong><\/p>\n<p>Java8 Files \u7c7b\u65b0\u589e\u4e86\u4e00\u4e2a lines\uff0c\u53ef\u4ee5\u8fd4\u56de Stream\u6211\u4eec\u53ef\u4ee5\u9010\u884c\u5904\u7406\u6570\u636e\u3002<\/p>\n<p>&nbsp;<\/p>\n<pre class=\"has-pre-numbering\"><code class=\"language-\">Stopwatch\u00a0stopwatch\u00a0=\u00a0Stopwatch.createStarted();\u00a0\n\/\/\u00a0lines(Path\u00a0path,\u00a0Charset\u00a0cs)\u00a0\ntry\u00a0(Stream&lt;String&gt;\u00a0inputStream\u00a0=\u00a0Files.lines(Paths.get(<span class=\"string\">\"temp\/test.txt\"<\/span>),\u00a0StandardCharsets.UTF_8))\u00a0{\u00a0\n\u00a0\u00a0\u00a0\u00a0inputStream\u00a0\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0.filter(str\u00a0-&gt;\u00a0str.length()\u00a0&gt;\u00a05)\/\/\u00a0\u8fc7\u6ee4\u6570\u636e\u00a0\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0.forEach(o\u00a0-&gt;\u00a0{\u00a0\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0pass\u00a0do\u00a0sample\u00a0logic\u00a0\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0});\u00a0\n}\u00a0\nlogMemory();\u00a0\nstopwatch.stop();\u00a0\nSystem.<span class=\"keyword\">out<\/span>.println(<span class=\"string\">\"read\u00a0all\u00a0lines\u00a0spend\u00a0\"<\/span>\u00a0+\u00a0stopwatch.elapsed(TimeUnit.SECONDS)\u00a0+\u00a0<span class=\"string\">\"\u00a0s\"<\/span>);\u00a0<\/code>\n\n\n<\/pre>\n<p>\u4f7f\u7528\u8fd9\u4e2a\u65b9\u6cd5\u6709\u4e2a\u597d\u5904\u5728\u4e8e\uff0c\u6211\u4eec\u53ef\u4ee5\u65b9\u4fbf\u4f7f\u7528 Stream \u94fe\u5f0f\u64cd\u4f5c\uff0c\u505a\u4e00\u4e9b\u8fc7\u6ee4\u64cd\u4f5c\u3002<\/p>\n<p>\u6ce8\u610f\uff1a\u8fd9\u91cc\u6211\u4eec\u4f7f\u7528 try-with-resources \u65b9\u5f0f\uff0c\u53ef\u4ee5\u5b89\u5168\u7684\u786e\u4fdd\u8bfb\u53d6\u7ed3\u675f\uff0c\u6d41\u53ef\u4ee5\u88ab\u5b89\u5168\u7684\u5173\u95ed\u3002<\/p>\n<p><code class=\"language-\">\u00a0<\/code><\/p>\n","protected":false},"excerpt":{"rendered":"<p>BufferReader \u6211\u4eec\u53ef\u4ee5\u4f7f\u7528 BufferReader#readLine \u9010\u884c\u8bfb\u53d6\u6570\u636e\u3002 try\u00a0(BufferedReader\u00a0fileBufferReader\u00a0=\u00a0new\u00a0BufferedReader(new\u00a0FileReader(&#8220;temp\/test.txt&#8221;)))\u00a0{\u00a0 \u00a0\u00a0\u00a0\u00a0String\u00a0fileLineContent;\u00a0 \u00a0\u00a0\u00a0\u00a0while\u00a0((fileLineContent\u00a0=\u00a0fileBufferReader.readLine())\u00a0!=\u00a0null)\u00a0{\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0process\u00a0the\u00a0line.\u00a0 \u00a0\u00a0\u00a0\u00a0}\u00a0 }\u00a0catch\u00a0(FileNotFoundException\u00a0e)\u00a0{\u00a0 \u00a0\u00a0\u00a0\u00a0e.printStackTrace();\u00a0 }\u00a0catch\u00a0(IOException\u00a0e)\u00a0{\u00a0 \u00a0\u00a0\u00a0\u00a0e.printStackTrace();\u00a0 }\u00a0 Apache Commons IOCommon-IO \u4e2d\u6709\u4e00\u4e2a\u65b9\u6cd5 FileUtils#lineIterator\u53ef\u4ee5\u5b9e\u73b0\u9010\u884c\u8bfb\u53d6\u65b9\u5f0f,\u4f7f\u7528\u4ee3\u7801\u5982\u4e0b\uff1a &nbsp; Stopwatch\u00a0stopwatch\u00a0=\u00a0Stopwatch.createStarted();\u00a0 LineIterator\u00a0fileContents\u00a0=\u00a0FileUtils.lineIterator(new\u00a0File(&#8220;temp\/test.txt&#8221;),\u00a0StandardCharsets.UTF_8.name());\u00a0 while\u00a0(fileContents.hasNext())\u00a0{\u00a0 \u00a0\u00a0\u00a0\u00a0fileContents.nextLine();\u00a0 \u00a0\u00a0\u00a0\u00a0\/\/\u00a0\u00a0pass\u00a0 }\u00a0 logMemory();\u00a0 fileContents.close();\u00a0 stopwatch.stop();\u00a0 System.out.println(&#8220;read\u00a0all\u00a0lines\u00a0spend\u00a0&#8221;\u00a0+\u00a0stopwatch.elapsed(TimeUnit.SECONDS)\u00a0+\u00a0&#8221;\u00a0s&#8221;); Java8 stream Java8 Files \u7c7b\u65b0\u589e\u4e86\u4e00\u4e2a lines\uff0c\u53ef\u4ee5\u8fd4\u56de Stream\u6211\u4eec\u53ef\u4ee5\u9010\u884c\u5904\u7406\u6570\u636e\u3002 &nbsp; Stopwatch\u00a0stopwatch\u00a0=\u00a0Stopwatch.createStarted();\u00a0 \/\/\u00a0lines(Path\u00a0path,\u00a0Charset\u00a0cs)\u00a0 try\u00a0(Stream&lt;String&gt;\u00a0inputStream\u00a0=\u00a0Files.lines(Paths.get(&#8220;temp\/test.txt&#8221;),\u00a0StandardCharsets.UTF_8))\u00a0{\u00a0 \u00a0\u00a0\u00a0\u00a0inputStream\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0.filter(str\u00a0-&gt;\u00a0str.length()\u00a0&gt;\u00a05)\/\/\u00a0\u8fc7\u6ee4\u6570\u636e\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0.forEach(o\u00a0-&gt;\u00a0{\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0pass\u00a0do\u00a0sample\u00a0logic\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0});\u00a0 }\u00a0 logMemory();\u00a0 stopwatch.stop();\u00a0 System.out.println(&#8220;read\u00a0all\u00a0lines\u00a0spend\u00a0&#8221;\u00a0+\u00a0stopwatch.elapsed(TimeUnit.SECONDS)\u00a0+\u00a0&#8221;\u00a0s&#8221;);\u00a0 \u4f7f\u7528\u8fd9\u4e2a\u65b9\u6cd5\u6709\u4e2a\u597d\u5904\u5728\u4e8e\uff0c\u6211\u4eec\u53ef\u4ee5\u65b9\u4fbf\u4f7f\u7528 Stream \u94fe\u5f0f\u64cd\u4f5c\uff0c\u505a\u4e00\u4e9b\u8fc7\u6ee4\u64cd\u4f5c\u3002 \u6ce8\u610f\uff1a\u8fd9\u91cc\u6211\u4eec\u4f7f\u7528 try-with-resources &#8230; <a title=\"java\u9ad8\u6548\u8bfb\u53d6\u5927\u6587\u4ef6\" class=\"read-more\" href=\"http:\/\/22pig.com\/?p=645\" aria-label=\"More on java\u9ad8\u6548\u8bfb\u53d6\u5927\u6587\u4ef6\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-645","post","type-post","status-publish","format-standard","hentry","category-java"],"_links":{"self":[{"href":"http:\/\/22pig.com\/index.php?rest_route=\/wp\/v2\/posts\/645","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/22pig.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/22pig.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/22pig.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/22pig.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=645"}],"version-history":[{"count":0,"href":"http:\/\/22pig.com\/index.php?rest_route=\/wp\/v2\/posts\/645\/revisions"}],"wp:attachment":[{"href":"http:\/\/22pig.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=645"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/22pig.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=645"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/22pig.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=645"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}