{"id":94577,"date":"2020-05-09T05:46:43","date_gmt":"2020-05-08T21:46:43","guid":{"rendered":"http:\/\/4563.org\/?p=94577"},"modified":"2020-05-09T05:46:43","modified_gmt":"2020-05-08T21:46:43","slug":"%e5%85%b3%e4%ba%8e-classloader-%e7%9a%84%e4%b8%80%e4%ba%9b%e7%96%91%e9%97%ae","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=94577","title":{"rendered":"\u5173\u4e8e ClassLoader \u7684\u4e00\u4e9b\u7591\u95ee"},"content":{"rendered":"
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\u5173\u4e8e ClassLoader \u7684\u4e00\u4e9b\u7591\u95ee <\/h1>\n

<\/p>\n

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\u8cc7\u6df1\u5927\u4f6c : yangyuhan12138 <\/span> <\/i> 17<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n

\u4f17\u6240\u5468\u77e5
<\/h1>\n

<\/p>\n

jvm \u91cc class \u7684\u552f\u4e00\u6807\u8bc6\u662f classloader+\u5305+\u7c7b
\u73b0\u5728\u6211\u81ea\u5b9a\u4e49\u4e86\u4e00\u4e2a classloader<\/p>\n

public class MyClassLoader extends ClassLoader <\/code><\/pre>\n
\u4ece\u5916\u90e8\u52a0\u8f7d\u6307\u5b9a\u7c7b\u8fdb\u5165 jvm<\/p>\n
        MyClassLoader mcl = new MyClassLoader();         Class<?> clazz = Class.forName(\"com.yuhan.demo.controller.People\", true, mcl);         obj = clazz.newInstance();         System.out.println(obj.getClass().getClassLoader());\/\/\u6253\u5370\u51fa\u6211\u4eec\u7684\u81ea\u5b9a\u4e49\u7c7b\u52a0\u8f7d\u5668  <\/code><\/pre>\n
\u8fd9\u79cd\u52a0\u8f7d\u65b9\u6cd5\u5e94\u8be5\u662f\u4f7f\u7528\u4e86\u53cc\u4eb2\u59d4\u6258\u673a\u5236\u5982\u679c AppClassLoader \u5df2\u7ecf\u52a0\u8f7d\u8fc7 People \u4e86\u5219\u4e0d\u4f1a\u91cd\u65b0\u52a0\u8f7d
 \u63a7\u5236\u53f0\u8f93\u51fa<\/p>\n
[email protected] <\/code><\/pre>\n
\u5982\u679c\u6211\u4eec\u5c06 People.class \u4ece classpath \u4e2d\u5220\u9664\u653e\u5230\u5176\u4ed6\u5730\u65b9,\u907f\u514d AppClassLoader \u76f4\u63a5\u52a0\u8f7d
 \u5219\u8f93\u51fa<\/p>\n
[email protected] <\/code><\/pre>\n
\u4f46\u662f\u5982\u679c\u6211\u4eec\u76f4\u63a5\u8fd9\u6837\u8c03\u7528<\/p>\n
       mcl = new MyClassLoader();        aClass = mcl.findClass(\"com.yuhan.demo.controller.People\");        obj =aClass.newInstance();        System.out.println(obj.getClass().getClassLoader());\/\/\u6253\u5370\u51fa\u6211\u4eec\u7684\u81ea\u5b9a\u4e49\u7c7b\u52a0\u8f7d\u5668 <\/code><\/pre>\n
\u5219\u4e0d\u7ba1 AppClassLoader \u662f\u5426\u52a0\u8f7d\u8fc7\u90fd\u4f1a\u7531 MyClassLoader \u6765\u52a0\u8f7d(\u76f8\u5f53\u4e8e\u7ed5\u8fc7\u4e86\u53cc\u4eb2?)<\/p>\n
\u73b0\u5728\u6211\u6709\u4e2a\u7591\u95ee\u5c31\u662f\u6211\u7528 findClass \u65b9\u6cd5\u52a0\u8f7d\u4e86\u4e00\u4e2a jvm \u4e2d\u5df2\u7ecf\u5b58\u5728\u7684 class(\u5305\u540d\u7c7b\u540d\u90fd\u76f8\u540c),\u76f8\u5f53\u4e8e jvm \u4e2d\u5c31\u6709\u4e24\u4e2a\u76f8\u540c\u7684 class \u4e86(jvm \u4e2d\u662f\u5141\u8bb8\u8fd9\u6837\u5b58\u5728\u7684\u56e0\u4e3a classloader \u4e0d\u540c) \u4f46\u662f java \u4e2d\u4f7f\u7528\u7c7b\u7684\u65f6\u5019\u53ea\u6307\u5b9a\u4e86\u5305\u540d\u548c\u7c7b\u540d\u5e76\u6ca1\u6709\u6307\u5b9a classloader \u90a3\u4e48 java \u662f\u5982\u4f55\u4fdd\u8bc1\u6211 new People \u7684\u65f6\u5019\u662f\u662f\u7528\u7684 AppClassLoader \u7684 People \u800c\u4e0d\u662f MyClassLoader \u7684 People \u5462<\/p>\n
\u6211\u7684\u731c\u6d4b\u662f\u6211\u4eec\u76f4\u63a5\u4f7f\u7528\u7c7b\u7684\u65f6\u5019 java \u52a0\u4e0a\u4e86\u9ed8\u8ba4\u7684 classloader \u4ece\u800c\u8fc7\u6ee4\u8c03\u4e86\u6211\u4eec\u81ea\u5df1\u52a0\u8f7d\u7684\u7c7b,\u800c\u6211\u4eec\u81ea\u5df1\u52a0\u8f7d\u7684\u7c7b\u5219\u53ea\u80fd\u901a\u8fc7\u53cd\u5c04\u6765\u8c03\u7528<\/p>\n<\/p><\/div>\n
 \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (12<\/span>)        <\/div>\n
 <\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : kaedea <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u7ebf\u7a0b ClassLoader \u4e86\u89e3\u4e00\u4e0b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : yangyuhan12138 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @kaedea 
    \u8c22\u8c22\u5927\u4f6c\u7684\u56de\u590d,\u6211\u53bb\u770b\u4e86\u4e0b context class loader \u5e76\u505a\u4e86\u5982\u4e0b\u5b9e\u9a8c
    “`
     MyClassLoader loader = new MyClassLoader();
     Thread.currentThread().setContextClassLoader(loader);
     obj = new People();
     System.out.println(obj.getClass());
     System.out.println(obj.getClass().getClassLoader());\/\/\u6253\u5370\u51fa\u6211\u4eec\u7684\u81ea\u5b9a\u4e49\u7c7b\u52a0\u8f7d\u5668
    “`
    \u8f93\u51fa
    class com.yuhan.demo.controller.People
    [email protected]<\/p>\n
    \u5f00\u59cb\u6211\u4ee5\u4e3a\u7684\u662f\u8bbe\u7f6e\u4e86 context class loader \u4e4b\u540e,\u4f1a\u53bb\u53d6\u6211\u8bbe\u7f6e\u7684 classloader load \u7684 class \u6765\u8fdb\u884c\u5b9e\u4f8b\u5316,\u4f46\u662f\u597d\u50cf\u5e76\u4e0d\u662f\u8fd9\u6837,\u8fd0\u884c\u7ed3\u679c\u4f9d\u7136\u4e3a AppClassLoader,\u5982\u679c\u6211\u60f3\u8981\u53d6 MyClassLoader load \u7684 People \u8fd8\u662f\u5f97 Thread.currentThread().getContextClassLoader() \u5c06 MyClassLoader \u53d6\u51fa\u6765\u4e4b\u540e\u518d loadclass,\u6240\u4ee5\u8fd9\u4e2a\u5730\u65b9\u5176\u5b9e\u76f8\u5f53\u4e8e\u53ea\u662f\u591a\u4e2a\u4e2a\u7ebf\u7a0b\u526f\u672c\u53d8\u91cf\u800c\u5df2,\u5982\u679c\u76f4\u63a5 new People()\u7684 People \u8fd8\u662f AppClassLoader load \u7684 People
    \u6240\u4ee5\u6211\u7684\u95ee\u9898\u7684\u7b54\u6848\u5e94\u8be5\u5c31\u662f\u6211\u5982\u679c\u4e0d\u4e3b\u52a8\u6307\u5b9a classloader \u6765 loadclass \u7684\u8bdd \u6211\u4eec\u662f\u4f7f\u7684\u6240\u6709\u7c7b\u90fd\u662f\u7531 Java \u4e2d\u7684\u7c7b\u52a0\u8f7d\u5668\u6765\u52a0\u8f7d\u7684?                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : james122333 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u679c\u7136\u5f88\u53ef\u7591\u963f haha \u6709\u8bb2\u4e0e\u6ca1\u8bb2\u5dee\u4e0d\u591a\u679c\u7136\u624d\u662f\u5bf9\u7684                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : sioncheng <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u53cc\u4eb2\u59d4\u6d3e\u6a21\u578b\uff0cBootstrap ClassLoader \/ExtClassLoader\/ AppClassLoader https:\/\/blog.csdn.net\/briblue\/article\/details\/54973413
    Thread Context Class Loader \u4e0e SPI https:\/\/blog.csdn.net\/liuchangqing123\/article\/details\/52304644                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : yangyuhan12138 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @james122333 \u554a?
    @sioncheng \u8fd9\u4e9b\u6211\u90fd\u770b\u4e86\u5440…\u7591\u95ee\u8fd8\u662f\u6ca1\u89e3\u51b3                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : mazai <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4f60\u8981\u627e\u7684\u7b54\u6848\u5c31\u5728 Launcher \u8fd9\u4e2a\u7c7b\u91cc\u9762\uff0c\u9996\u5148 JVM \u5728\u521d\u59cb\u5316\u7684\u65f6\u5019\u542f\u52a8\u7c7b\u52a0\u8f7d\u5668\u4f1a\u9996\u5148\u88ab\u865a\u62df\u673a\u6267\u884c\uff08\u4e00\u6bb5 C++\u4ee3\u7801\uff09\uff0c\u800c Launcher \u8fd9\u4e2a\u7c7b\u6b63\u662f\u542f\u52a8\u7c7b\u52a0\u8f7d\u5668\u6765\u52a0\u8f7d\u7684\u3002<\/p>\n
    \u4ed6\u6709\u4e00\u4e2a\u5168\u5c40\u9759\u6001\u53d8\u91cf private static Launcher launcher = new Launcher(); \u56e0\u6b64 Launcher \u7684\u6784\u9020\u51fd\u6570\u4f1a\u88ab\u8c03\u7528\uff0c\u4ee5\u4e0b\u6211\u622a\u51fa\u51e0\u6bb5\u6784\u9020\u51fd\u6570\u7684\u4ee3\u7801\u4f60\u5c31\u660e\u767d\u4e86\uff1a
    this.loader = Launcher.AppClassLoader.getAppClassLoader(var1);<\/p>\n
    Thread.currentThread().setContextClassLoader(this.loader);<\/p>\n
    var3 = (SecurityManager)this.loader.loadClass(var2).newInstance();<\/p>\n
    \u66f4\u8be6\u7ec6\u7684\u4f60\u81ea\u5df1\u53bb\u770b Launcher \u8fd9\u4e2a\u7c7b\u7684\u4ee3\u7801\u5c31\u597d\u4e86\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : fantastM <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4f60\u60f3\u95ee\u662f\u7684 ClassLoader A \u52a0\u8f7d\u4e86 Class A\uff0c\u4e3a\u4ec0\u4e48\u5728\u6ca1\u6709\u663e\u5f0f\u58f0\u660e\u4f7f\u7528 ClassLoader A \u7684\u60c5\u51b5\u4e0b\u5c31\u53ef\u4ee5\u52a0\u8f7d Class A \u4f9d\u8d56\u7684 Class B \u5417                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : yangyuhan12138 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @fantastM \u4e0d\u662f\u5440….\u6211\u7684\u610f\u601d\u662f\u540c\u540d class \u4e0d\u540c classloader \u52a0\u8f7d\u8fdb jvm \u7684 \u5728\u6211\u4eec\u76f4\u63a5 new \u7684\u65f6\u5019\u5230\u5e95\u662f\u4f7f\u7528\u7684\u90a3\u4e2a classloader \u52a0\u8f7d\u8fdb\u6765\u7684 class                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : pursuer <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 1 \u3001java \u4e0d\u9700\u8981\u4fdd\u8bc1\u7c7b\u662f\u4ece\u54ea\u4e2a classloader \u52a0\u8f7d\u7684
    2 \u3001\u5e76\u4e0d\u662f\u53ea\u80fd\u901a\u8fc7\u53cd\u5c04\u8c03\u7528\uff0c\u4f60\u751a\u81f3\u53ef\u4ee5\u81ea\u5b9a\u4e49 classloader \u7834\u574f\u53cc\u4eb2\u59d4\u6d3e\u66ff\u6362\u6389\u4e00\u4e2a\u672c\u6765\u5df2\u7ecf\u52a0\u8f7d\u7684\u7c7b\u53bb                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : fantastM <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u300c\u6211\u4eec\u76f4\u63a5 new \u7684\u65f6\u5019\u300d\u8fd9\u65f6\u5019\u7a0b\u5e8f\u5df2\u7ecf\u8fd0\u884c\u5728\u4e00\u4e2a\u88ab ClassLoader \u52a0\u8f7d\u7684\u7c7b\u91cc\u4e86\uff0c\u9ed8\u8ba4\u5c31\u4f1a\u7528\u8fd9\u4e2a ClassLoader \u53bb\u52a0\u8f7d\u5f53\u524d\u7c7b\u4f9d\u8d56\u7684\u8fd8\u6ca1\u6709\u88ab\u52a0\u8f7d\u7684\u5176\u5b83\u7c7b\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : yangyuhan12138 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @fantastM \u5df2\u52a0\u8f7d\u7684\u4e5f\u4f1a\u4f18\u5148\u4f7f\u7528\u5f53\u524d classloader \u52a0\u8f7d\u7684 \u6211\u521a\u8bd5\u7684\u5c31\u662f\u8fd9\u6837                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : yangyuhan12138 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @pursuer \u6211\u73b0\u5728\u4e0d\u5c31\u662f\u8fd9\u6837\u505a\u7684\u5417 \u52a0\u8f7d\u4e00\u4e2a\u5df2\u7ecf\u5b58\u5728\u7684\u7c7b \u53ea\u662f classloader \u4e0d\u540c                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"
    \u5173\u4e8e ClassLoader \u7684\u4e00…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/94577"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=94577"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/94577\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=94577"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=94577"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=94577"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}