{"id":10175,"date":"2023-11-28T21:28:09","date_gmt":"2023-11-28T13:28:09","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=10175"},"modified":"2023-12-07T10:57:28","modified_gmt":"2023-12-07T02:57:28","slug":"jvm-ru-he-pan-duan-yi-ge-lei-shi-wu-yong-de-lei","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/11\/28\/jvm-ru-he-pan-duan-yi-ge-lei-shi-wu-yong-de-lei\/","title":{"rendered":"JVM\u5982\u4f55\u5224\u65ad\u4e00\u4e2a\u7c7b\u662f\u65e0\u7528\u7684\u7c7b\uff1f"},"content":{"rendered":"

\u5728Java\u865a\u62df\u673a\u4e2d\uff0c\u5224\u65ad\u4e00\u4e2a\u7c7b\u662f\u5426\u662f\u65e0\u7528\u7684\u7c7b\u901a\u5e38\u901a\u8fc7\u7c7b\u7684\u7c7b\u52a0\u8f7d\u5668<\/strong>\u548c\u7c7b\u7684\u5f15\u7528\u5173\u7cfb<\/strong>\u6765\u8fdb\u884c\u5224\u65ad\u3002\u5982\u679c\u4e00\u4e2a\u7c7b\u6ee1\u8db3\u4ee5\u4e0b\u6761\u4ef6\uff0c\u53ef\u4ee5\u8ba4\u4e3a\u5b83\u662f\u65e0\u7528\u7684\u7c7b\uff0c\u5373\u53ef\u4ee5\u88ab\u5783\u573e\u56de\u6536\uff1a<\/p>\n

    \n
  1. \n\u7c7b\u52a0\u8f7d\u5668\u88ab\u56de\u6536\uff1a<\/strong> \u5982\u679c\u4e00\u4e2a\u7c7b\u7684ClassLoader<\/code>\u88ab\u56de\u6536\uff0c\u8bf4\u660e\u8fd9\u4e2a\u7c7b\u5df2\u7ecf\u4e0d\u518d\u88ab\u9700\u8981\uff0c\u56e0\u4e3a\u7c7b\u52a0\u8f7d\u5668\u7684\u751f\u547d\u5468\u671f\u6bd4\u7c7b\u7684\u751f\u547d\u5468\u671f\u66f4\u77ed\u3002\n<\/li>\n
  2. \n\u6ca1\u6709\u6d3b\u52a8\u7684\u5b9e\u4f8b\uff1a<\/strong> \u5982\u679c\u4e00\u4e2a\u7c7b\u6ca1\u6709\u4efb\u4f55\u6d3b\u52a8\u7684\u5b9e\u4f8b\uff0c\u4e5f\u5c31\u662f\u6ca1\u6709\u88ab\u4efb\u4f55\u5bf9\u8c61\u5f15\u7528\uff0c\u90a3\u4e48\u8fd9\u4e2a\u7c7b\u5c31\u662f\u65e0\u7528\u7684\u3002\n<\/li>\n
  3. \n\u6ca1\u6709\u6d3b\u52a8\u7684\u7c7b\u5f15\u7528\uff1a<\/strong> \u5982\u679c\u4e00\u4e2a\u7c7b\u6ca1\u6709\u88ab\u5176\u4ed6\u7c7b\u5f15\u7528\uff0c\u4e5f\u5c31\u662f\u6ca1\u6709\u5176\u4ed6\u7c7b\u4e2d\u7684\u5b57\u6bb5\u3001\u65b9\u6cd5\u7b49\u5f15\u7528\u5230\u5b83\uff0c\u90a3\u4e48\u8fd9\u4e2a\u7c7b\u4e5f\u53ef\u4ee5\u88ab\u5224\u5b9a\u4e3a\u65e0\u7528\u7684\u3002\n<\/li>\n<\/ol>\n

    \u5728Java 8\u4e4b\u524d\uff0c\u8981\u5224\u65ad\u4e00\u4e2a\u7c7b\u662f\u5426\u88ab\u52a0\u8f7d\u548c\u521d\u59cb\u5316\uff0c\u53ef\u4ee5\u4f7f\u7528java.lang.management.ClassLoadingMXBean<\/code>\u63a5\u53e3\u3002\u5728Java 8\u53ca\u4e4b\u540e\u7684\u7248\u672c\uff0c\u53ef\u4ee5\u901a\u8fc7java.lang.invoke.MethodHandles.Lookup<\/code>\u6765\u5b9e\u73b0\u3002<\/p>\n

    \u4e0b\u9762\u662f\u4e00\u4e2a\u7b80\u5355\u7684\u793a\u4f8b\uff0c\u6f14\u793a\u4e86\u5982\u4f55\u4f7f\u7528ClassLoader<\/code>\u548cClassLoadingMXBean<\/code>\u6765\u5224\u65ad\u4e00\u4e2a\u7c7b\u662f\u5426\u662f\u65e0\u7528\u7684\u7c7b\uff1a<\/p>\n

    import java.lang.management.ClassLoadingMXBean;\nimport java.lang.management.ManagementFactory;\n\npublic class UnloadClassExample {\n\n    public static void main(String[] args) throws Exception {\n        \/\/ \u52a0\u8f7d\u7c7b\n        ClassLoader classLoader = new CustomClassLoader();\n        Class<?> loadedClass = classLoader.loadClass("ExampleClass");\n\n        \/\/ \u5b9e\u4f8b\u5316\u7c7b\n        Object instance = loadedClass.newInstance();\n\n        \/\/ \u6253\u5370\u7c7b\u52a0\u8f7d\u4fe1\u606f\n        printClassLoadingInfo();\n\n        \/\/ \u8bbe\u7f6e\u5f15\u7528\u4e3anull\uff0c\u4f7f\u5f97\u8be5\u7c7b\u53d8\u6210\u65e0\u7528\u7684\u7c7b\n        instance = null;\n\n        \/\/ \u6267\u884c\u5783\u573e\u56de\u6536\n        System.gc();\n\n        \/\/ \u518d\u6b21\u6253\u5370\u7c7b\u52a0\u8f7d\u4fe1\u606f\n        printClassLoadingInfo();\n    }\n\n    private static void printClassLoadingInfo() {\n        ClassLoadingMXBean classLoadingMXBean = ManagementFactory.getClassLoadingMXBean();\n        System.out.println("Total Loaded Class Count: " + classLoadingMXBean.getTotalLoadedClassCount());\n        System.out.println("Unloaded Class Count: " + classLoadingMXBean.getUnloadedClassCount());\n    }\n}\n\nclass CustomClassLoader extends ClassLoader {\n    \/\/ \u81ea\u5b9a\u4e49\u7c7b\u52a0\u8f7d\u5668\u5b9e\u73b0\n}\n\nclass ExampleClass {\n    \/\/ \u793a\u4f8b\u7c7b\n}\n<\/code><\/pre>\n
    \u5728\u4e0a\u8ff0\u793a\u4f8b\u4e2d\uff0c\u901a\u8fc7\u52a0\u8f7d\u4e00\u4e2a\u7c7b\u3001\u5b9e\u4f8b\u5316\u8be5\u7c7b\u3001\u5c06\u5f15\u7528\u7f6e\u4e3anull\uff0c\u7136\u540e\u6267\u884c\u5783\u573e\u56de\u6536\uff0c\u901a\u8fc7ClassLoadingMXBean<\/code>\u7684\u4fe1\u606f\u53ef\u4ee5\u89c2\u5bdf\u5230\u7c7b\u662f\u5426\u88ab\u5378\u8f7d\u3002\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u5783\u573e\u56de\u6536\u662f\u7531\u5783\u573e\u56de\u6536\u5668\u81ea\u52a8\u89e6\u53d1\u7684\uff0c\u8c03\u7528System.gc()<\/code>\u5e76\u4e0d\u4e00\u5b9a\u4f1a\u7acb\u5373\u6267\u884c\u5783\u573e\u56de\u6536\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
    \u5728Java\u865a\u62df\u673a\u4e2d\uff0c\u5224\u65ad\u4e00\u4e2a\u7c7b\u662f\u5426\u662f\u65e0\u7528\u7684\u7c7b\u901a\u5e38\u901a\u8fc7\u7c7b\u7684\u7c7b\u52a0\u8f7d\u5668\u548c\u7c7b\u7684\u5f15\u7528\u5173\u7cfb\u6765\u8fdb\u884c\u5224\u65ad\u3002\u5982\u679c\u4e00\u4e2a\u7c7b\u6ee1\u8db3\u4ee5\u4e0b\u6761 […]<\/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-10175","post","type-post","status-publish","format-standard","hentry","category-jvm"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/10175","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=10175"}],"version-history":[{"count":2,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/10175\/revisions"}],"predecessor-version":[{"id":16810,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/10175\/revisions\/16810"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=10175"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=10175"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=10175"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}