{"id":11308,"date":"2023-11-28T21:59:25","date_gmt":"2023-11-28T13:59:25","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=11308"},"modified":"2023-12-08T11:43:57","modified_gmt":"2023-12-08T03:43:57","slug":"jvm-zhong-zhi-jie-nei-cun-shi-shen-me","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/11\/28\/jvm-zhong-zhi-jie-nei-cun-shi-shen-me\/","title":{"rendered":"JVM\u4e2d\u76f4\u63a5\u5185\u5b58\u662f\u4ec0\u4e48\uff1f"},"content":{"rendered":"<p>\u76f4\u63a5\u5185\u5b58\uff08Direct Memory\uff09\u6307\u7684\u662f\u5728Java\u7a0b\u5e8f\u4e2d\u901a\u8fc7 <code>ByteBuffer<\/code> \u7c7b\u7684 <code>allocateDirect<\/code> \u65b9\u6cd5\u5206\u914d\u7684\u4e00\u5757\u5185\u5b58\uff0c\u800c\u4e0d\u662f\u901a\u8fc7\u4f20\u7edf\u7684 Java \u5806\u5185\u5b58\uff08\u901a\u8fc7 <code>new<\/code> \u64cd\u4f5c\u7b26\u521b\u5efa\u5bf9\u8c61\uff09\u5206\u914d\u3002\u8fd9\u79cd\u76f4\u63a5\u5185\u5b58\u7684\u4f7f\u7528\u65b9\u5f0f\u4e0e\u666e\u901a\u7684\u5806\u5185\u5b58\u6709\u4e00\u4e9b\u533a\u522b\u3002<\/p>\n<p>\u4e3b\u8981\u7684\u533a\u522b\u5728\u4e8e\uff0c\u76f4\u63a5\u5185\u5b58\u7684\u5206\u914d\u548c\u91ca\u653e\u5e76\u4e0d\u53d7 Java \u5806\u5927\u5c0f\u7684\u9650\u5236\uff0c\u800c\u662f\u53d7\u5236\u4e8e\u672c\u5730\u5185\u5b58\u7684\u5927\u5c0f\u3002\u5b83\u662f\u4f7f\u7528\u672c\u5730\u65b9\u6cd5\u5e93\u6765\u76f4\u63a5\u5206\u914d\u5185\u5b58\uff0c\u56e0\u6b64\u4e0d\u53d7Java\u5806\u5927\u5c0f\u7684\u9650\u5236\uff0c\u4e5f\u4e0d\u4f1a\u53d7\u5230Java\u5806\u5783\u573e\u56de\u6536\u7684\u5f71\u54cd\u3002\u76f4\u63a5\u5185\u5b58\u7684\u5206\u914d\u548c\u91ca\u653e\u662f\u6bd4\u8f83\u6602\u8d35\u7684\uff0c\u56e0\u4e3a\u6d89\u53ca\u5230\u672c\u5730\u65b9\u6cd5\u7684\u8c03\u7528\uff0c\u4f46\u5728\u4e00\u4e9b\u7279\u5b9a\u573a\u666f\u4e0b\uff0c\u5b83\u53ef\u4ee5\u63d0\u4f9b\u66f4\u9ad8\u6548\u7684I\/O \u64cd\u4f5c\u3002<\/p>\n<p><code>ByteBuffer<\/code> \u7c7b\u63d0\u4f9b\u4e86\u4e00\u79cd\u76f4\u63a5\u8bbf\u95ee\u76f4\u63a5\u5185\u5b58\u7684\u65b9\u5f0f\uff0c\u901a\u8fc7\u8be5\u7c7b\u7684 <code>allocateDirect<\/code> \u65b9\u6cd5\u521b\u5efa\u7684 <code>ByteBuffer<\/code> \u5bf9\u8c61\u5b9e\u9645\u4e0a\u662f\u5bf9\u76f4\u63a5\u5185\u5b58\u7684\u5c01\u88c5\u3002\u4f7f\u7528\u76f4\u63a5\u5185\u5b58\u53ef\u4ee5\u5728\u8fdb\u884c\u5927\u91cf\u6570\u636e\u4f20\u8f93\u65f6\u63d0\u9ad8\u6027\u80fd\uff0c\u5c24\u5176\u5728 I\/O \u64cd\u4f5c\u4e2d\uff0c\u53ef\u4ee5\u901a\u8fc7 <code>java.nio<\/code> \u5305\u4e2d\u7684\u901a\u9053\uff08Channel\uff09\u8fdb\u884c\u96f6\u62f7\u8d1d\u64cd\u4f5c\uff0c\u51cf\u5c11\u4e86\u6570\u636e\u4ece\u5806\u5185\u5b58\u5230\u76f4\u63a5\u5185\u5b58\u7684\u590d\u5236\u5f00\u9500\u3002<\/p>\n<p>\u4ee5\u4e0b\u662f\u4f7f\u7528 <code>ByteBuffer<\/code> \u5206\u914d\u76f4\u63a5\u5185\u5b58\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code class=\"language-java\">import java.nio.ByteBuffer;\n\npublic class DirectMemoryExample {\n    public static void main(String[] args) {\n        \/\/ \u5206\u914d\u76f4\u63a5\u5185\u5b58\uff0c\u5927\u5c0f\u4e3a 1MB\n        ByteBuffer directBuffer = ByteBuffer.allocateDirect(1024 * 1024);\n        \n        \/\/ \u4f7f\u7528\u76f4\u63a5\u5185\u5b58\u8fdb\u884c\u4e00\u4e9b\u64cd\u4f5c\n        \/\/ ...\n        \n        \/\/ \u91ca\u653e\u76f4\u63a5\u5185\u5b58\uff0c\u6ce8\u610f\uff1a\u76f4\u63a5\u5185\u5b58\u7684\u91ca\u653e\u4e0d\u7531\u5783\u573e\u56de\u6536\u5668\u8d1f\u8d23\uff0c\u9700\u8981\u624b\u52a8\u91ca\u653e\n        directBuffer.clear(); \/\/ \u6e05\u7a7a\u7f13\u51b2\u533a\n        sun.misc.Cleaner cleaner = ((sun.nio.ch.DirectBuffer) directBuffer).cleaner();\n        if (cleaner != null) {\n            cleaner.clean();\n        }\n    }\n}\n<\/code><\/pre>\n<p>\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u4e0a\u8ff0\u793a\u4f8b\u4e2d\u7684 <code>sun.misc.Cleaner<\/code> \u662f\u7528\u4e8e\u624b\u52a8\u91ca\u653e\u76f4\u63a5\u5185\u5b58\u7684\uff0c\u5b83\u662f\u4e00\u79cd\u975e\u6807\u51c6\u7684 API\uff0c\u56e0\u6b64\u5728\u5b9e\u9645\u751f\u4ea7\u4ee3\u7801\u4e2d\uff0c\u6700\u597d\u8003\u8651\u4f7f\u7528\u66f4\u7a33\u5b9a\u7684\u624b\u6bb5\u6765\u7ba1\u7406\u76f4\u63a5\u5185\u5b58\u7684\u91ca\u653e\u3002\u5728Java 9\u53ca\u4ee5\u540e\u7684\u7248\u672c\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>java.lang.ref.Cleaner<\/code> \u7c7b\u6765\u66ff\u4ee3\u4e0a\u8ff0\u7684 <code>sun.misc.Cleaner<\/code>\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u76f4\u63a5\u5185\u5b58\uff08Direct Memory\uff09\u6307\u7684\u662f\u5728Java\u7a0b\u5e8f\u4e2d\u901a\u8fc7 ByteBuffer \u7c7b\u7684 allocate [&hellip;]<\/p>\n","protected":false},"author":9,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[119],"tags":[],"class_list":["post-11308","post","type-post","status-publish","format-standard","hentry","category-jvm"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/11308","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=11308"}],"version-history":[{"count":2,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/11308\/revisions"}],"predecessor-version":[{"id":16990,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/11308\/revisions\/16990"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=11308"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=11308"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=11308"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}