{"id":10008017,"date":"2023-06-29T12:59:27","date_gmt":"2023-06-29T04:59:27","guid":{"rendered":"https:\/\/ityet.com\/?p=10008017"},"modified":"2023-06-29T12:59:27","modified_gmt":"2023-06-29T04:59:27","slug":"java%e5%8f%8d%e5%b0%84%e6%ba%90%e7%a0%81%e5%ad%a6%e4%b9%a0%e4%b9%8b%e6%97%85-%e4%ba%ac%e4%b8%9c%e4%ba%91%e6%8a%80%e6%9c%af%e5%9b%a2%e9%98%9f","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10008017","title":{"rendered":"Java\u53cd\u5c04\u6e90\u7801\u5b66\u4e60\u4e4b\u65c5 | \u4eac\u4e1c\u4e91\u6280\u672f\u56e2\u961f"},"content":{"rendered":"<h2>1 \u80cc\u666f<\/h2>\n<p>\u524d\u6bb5\u65f6\u95f4\u7ec4\u5185\u9488\u5bf9\u201c\u62f7\u8d1d\u5b9e\u4f8b\u5c5e\u6027\u662f\u5e94\u8be5\u7528BeanUtils.copyProperties\uff08\uff09\u8fd8\u662fMapStruct\u201d\u8fd9\u4e2a\u95ee\u9898\u8fdb\u884c\u4e86\u4e00\u6b21\u6fc0\u70c8\u7684battle\u3002\u652f\u6301MapStruct\u7684\u540c\u5b66\u7ed9\u51fa\u4e86\u4ed6\u5acc\u5f03BeanUtils\u7684\u7406\u7531\uff1a\u56e0\u4e3a\u7528\u4e86\u53cd\u5c04\uff0c\u6240\u4ee5\u6162\u3002<\/p>\n<p>\u8fd9\u4e2a\u7406\u7531\u4e00\u4e0b\u5b50\u62c9\u56de\u4e86\u6211\u9065\u8fdc\u7684\u8bb0\u5fc6\uff0c\u5728\u6211\u521a\u5f00\u59cb\u4e86\u89e3\u53cd\u5c04\u8fd9\u4e2aJava\u7279\u6027\u7684\u65f6\u5019\uff0c\u51e0\u4e4e\u770b\u5230\u7684\u6bcf\u4e00\u7bc7\u6587\u7ae0\u90fd\u4f1a\u6709\u201cJava\u53cd\u5c04\u4e0d\u80fd\u9891\u7e41\u4f7f\u7528\u201d\u3001\u201c\u53cd\u5c04\u5f71\u54cd\u6027\u80fd\u201d\u4e4b\u7c7b\u7684\u8bdd\u8bed\uff0c\u5f53\u65f6\u53ea\u662f\u5f53\u4e00\u4e2a\u7ed3\u8bba\u8bb0\u4e0b\u4e86\u8fd9\u4e9b\u8bdd\uff0c\u5374\u6ca1\u6709\u6df1\u7a76\u8fc7\u4e3a\u4ec0\u4e48\uff0c\u6240\u4ee5\u6b63\u597d\u501f\u6b64\u673a\u4f1a\u6765\u63a2\u7a76\u4e00\u4e0bJava\u53cd\u5c04\u7684\u4ee3\u7801\u3002<\/p>\n<h2>2 \u53cd\u5c04\u5305\u7ed3\u6784\u68b3\u7406<\/h2>\n<p>\u53cd\u5c04\u76f8\u5173\u7684\u4ee3\u7801\u4e3b\u8981\u5728jdk rt.jar\u4e0b\u7684java.lang.reflect\u5305\u4e0b\uff0c\u8fd8\u6709\u4e00\u4e9b\u76f8\u5173\u7c7b\u5728\u5176\u4ed6\u5305\u8def\u5f84\u4e0b\uff0c\u8fd9\u91cc\u5148\u6309\u4e0b\u4e0d\u8868\u3002\u6309\u7167\u7ee7\u627f\u548c\u5b9e\u73b0\u7684\u5173\u7cfb\u5148\u7b80\u5355\u5212\u5206\u4e0bjava.lang.reflect\u5305\uff1a<\/p>\n<p>\u2460 Constructor\u3001Method\u3001Field\u4e09\u4e2a\u7c7b\u578b\u5206\u522b\u53ef\u4ee5\u63cf\u8ff0\u5b9e\u4f8b\u7684\u6784\u9020\u65b9\u6cd5\u3001\u666e\u901a\u65b9\u6cd5\u548c\u5b57\u6bb5\u3002\u4e09\u79cd\u7c7b\u578b\u90fd\u76f4\u63a5\u6216\u95f4\u63a5\u7ee7\u627f\u4e86AccessibleObject\u8fd9\u4e2a\u7c7b\u578b\uff0c\u6b64\u7c7b\u578b\u91cc\u4e3b\u8981\u5b9a\u4e49\u4e24\u79cd\u65b9\u6cd5\uff0c\u4e00\u79cd\u662f\u901a\u7528\u7684\u3001\u5bf9\u8bbf\u95ee\u6743\u9650\u8fdb\u884c\u5904\u7406\u7684\u65b9\u6cd5\uff0c\u7b2c\u4e8c\u79cd\u662f\u53ef\u4f9b\u7ee7\u627f\u91cd\u5199\u7684\u3001\u4e0e\u6ce8\u89e3\u76f8\u5173\u7684\u65b9\u6cd5\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043948618\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u2461 \u53ea\u770b\u9009\u4e2d\u7684\u4e94\u79cd\u7c7b\u578b\uff0c\u6211\u4eec\u5e73\u5e38\u6240\u7528\u5230\u7684\u666e\u901a\u7c7b\u578b\uff0c\u8b6c\u5982Integer\u3001String\uff0c\u53c8\u6216\u8005\u662f\u6211\u4eec\u81ea\u5b9a\u4e49\u7684\u7c7b\u578b\uff0c\u90fd\u53ef\u4ee5\u7528Class\u7c7b\u578b\u7684\u5b9e\u4f8b\u6765\u8868\u793a\u3002Java\u5f15\u5165\u6cdb\u578b\u4e4b\u540e\uff0c\u5728JDK1.5\u4e2d\u6269\u5145\u4e86\u5176\u4ed6\u56db\u79cd\u7c7b\u578b\uff0c\u7528\u4e8e\u6cdb\u578b\u7684\u8868\u793a\u3002\u5206\u522b\u662fParameterizedType(\u53c2\u6570\u5316\u7c7b\u578b)\u3001WildcardType\uff08\u901a\u914d\u7b26\u7c7b\u578b\uff09\u3001TypeVariable\uff08\u7c7b\u578b\u53d8\u91cf\uff09\u3001GenericArrayType\uff08\u6cdb\u578b\u6570\u7ec4\uff09\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043948619\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u2462 \u4e0e\u2461\u4e2d\u63cf\u8ff0\u7684\u4e94\u79cd\u57fa\u672c\u7c7b\u578b\u5bf9\u5e94\uff0c\u4e0b\u56fe\u8fd9\u4e94\u4e2a\u63a5\u53e3\/\u7c7b\u5206\u522b\u7528\u6765\u8868\u793a\u4e94\u79cd\u57fa\u672c\u7c7b\u578b\u7684\u6ce8\u89e3\u76f8\u5173\u6570\u636e\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043948620\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u2463 \u4e0b\u56fe\u4e3a\u5b9e\u73b0\u52a8\u6001\u4ee3\u7406\u7684\u76f8\u5173\u7c7b\u4e0e\u63a5\u53e3\u3002java.lang.reflect.Proxy\u4e3b\u8981\u662f\u5229\u7528\u53cd\u5c04\u7684\u4e00\u4e9b\u65b9\u6cd5\u83b7\u53d6\u4ee3\u7406\u7c7b\u7684\u7c7b\u5bf9\u8c61\uff0c\u83b7\u53d6\u5176\u6784\u9020\u65b9\u6cd5\uff0c\u7531\u6b64\u6784\u9020\u51fa\u4e00\u4e2a\u5b9e\u4f8b\u3002 <\/p>\n<p>java.lang.reflect.InvocationHandler\u662f\u4ee3\u7406\u7c7b\u9700\u8981\u5b9e\u73b0\u7684\u63a5\u53e3\uff0c\u7531\u4ee3\u7406\u7c7b\u5b9e\u73b0\u63a5\u53e3\u5185\u7684invoke\u65b9\u6cd5\uff0c\u6b64\u65b9\u6cd5\u4f1a\u8d1f\u8d23\u4ee3\u7406\u6d41\u7a0b\u548c\u88ab\u4ee3\u7406\u6d41\u7a0b\u7684\u6267\u884c\u987a\u5e8f\u7ec4\u7ec7\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043948621\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043948622\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<h2>3 \u76ee\u6807\u7c7b\u5b9e\u4f8b\u7684\u6784\u9020\u6e90\u7801<\/h2>\n<p>\u4ee5String\u7c7b\u7684\u5bf9\u8c61\u5b9e\u4f8b\u5316\u4e3a\u4f8b\uff0c\u770b\u4e00\u4e0b\u53cd\u5c04\u662f\u5982\u4f55\u8fdb\u884c\u5bf9\u8c61\u5b9e\u4f8b\u5316\u7684\u3002<\/p>\n<pre><code>Class&lt;?&gt; clz = Class.forName(&quot;java.lang.String&quot;);\nString s  =(String)clz.newInstance();<\/code><\/pre>\n<p>Class\u5bf9\u8c61\u7684\u6784\u9020\u7531native\u65b9\u6cd5\u5b8c\u6210\uff0c\u4ee5java.lang.String\u7c7b\u4e3a\u4f8b\uff0c\u5148\u770b\u770b\u6784\u9020\u597d\u7684Class\u5bf9\u8c61\u90fd\u6709\u54ea\u4e9b\u5c5e\u6027\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043948623\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u53ef\u4ee5\u770b\u5230\u76ee\u524d\u53ea\u6709name\u4e00\u4e2a\u5c5e\u6027\u6709\u503c\uff0c\u5176\u4f59\u5c5e\u6027\u6682\u65f6\u90fd\u662fnull\u6216\u8005\u9ed8\u8ba4\u503c\u7684\u72b6\u6001\u3002  <br \/>\u4e0b\u56fe\u662f clz.newInstance() \u65b9\u6cd5\u903b\u8f91\u7684\u6d41\u7a0b\u56fe\uff0c\u63a5\u4e0b\u6765\u5bf9\u5176\u4e2d\u4e3b\u8981\u7684\u4e24\u4e2a\u65b9\u6cd5\u8fdb\u884c\u8bf4\u660e\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043948624\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u4ece\u4e0a\u56fe\u53ef\u4ee5\u770b\u51fa\u6574\u4e2a\u6d41\u7a0b\u6709\u4e24\u4e2a\u6838\u5fc3\u90e8\u5206\u3002\u56e0\u4e3a\u901a\u5e38\u60c5\u51b5\u4e0b\uff0c\u5bf9\u8c61\u7684\u6784\u9020\u90fd\u9700\u8981\u4f9d\u9760\u7c7b\u91cc\u7684\u6784\u9020\u65b9\u6cd5\u6765\u5b9e\u73b0\uff0c\u6240\u4ee5\u7b2c\u4e00\u90e8\u5206\u5c31\u662f\u62ff\u5230\u76ee\u6807\u7c7b\u5bf9\u5e94\u7684Constructor\u5bf9\u8c61\uff1b\u7b2c\u4e8c\u90e8\u5206\u5c31\u662f\u5229\u7528Constructor\u5bf9\u8c61\uff0c\u6784\u9020\u76ee\u6807\u7c7b\u7684\u5b9e\u4f8b\u3002<\/p>\n<h3>3.1 \u83b7\u53d6Constructor\u5bf9\u8c61<\/h3>\n<p>\u9996\u5148\u4e0a\u4e00\u5f20Constructor\u5bf9\u8c61\u7684\u5c5e\u6027\u56fe\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043948625\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>java.lang.Class#getConstructor0<\/p>\n<p>\u6b64\u65b9\u6cd5\u4e2d\u4e3b\u8981\u505a\u7684\u5de5\u4f5c\u662f\u9996\u5148\u62ff\u5230\u76ee\u6807\u7c7b\u7684Constructor\u5b9e\u4f8b\u6570\u7ec4(\u4e3b\u8981\u7531native\u65b9\u6cd5\u5b9e\u73b0)\uff0c\u6570\u7ec4\u91cc\u6bcf\u4e00\u4e2a\u5bf9\u8c61\u90fd\u4ee3\u8868\u4e86\u76ee\u6807\u7c7b\u7684\u4e00\u4e2a\u6784\u9020\u65b9\u6cd5\u3002\u7136\u540e\u5bf9\u6570\u7ec4\u8fdb\u884c\u904d\u5386\uff0c\u6839\u636e\u65b9\u6cd5\u5165\u53c2\u63d0\u4f9b\u7684parameterTypes,\u627e\u5230\u7b26\u5408\u7684Constructor\u5bf9\u8c61\uff0c\u7136\u540e\u91cd\u65b0\u521b\u9020\u4e00\u4e2aConstructor\u5bf9\u8c61\uff0c\u5c5e\u6027\u503c\u4e0e\u539fConstructor\u4e00\u81f4\uff08\u79f0\u4e3a\u526f\u672cConstructor\uff09\uff0c\u5e76\u4e14\u526f\u672cConstructor\u7684\u5c5e\u6027 root \u6307\u5411\u6e90Constructor\uff0c\u76f8\u5f53\u4e8e\u5bf9\u6e90Constructor\u5bf9\u8c61\u8fdb\u884c\u4e86\u4e00\u5c42\u5c01\u88c5\u3002<\/p>\n<p>\u7531\u4e8e\u5728getConstructor0()\u65b9\u6cd5\u5c06\u8fd4\u56de\u503c\u8fd4\u56de\u7ed9\u8c03\u7528\u65b9\u4e4b\u540e\uff0c\u8c03\u7528\u65b9\u5728\u540e\u7eed\u7684\u6d41\u7a0b\u91cc\u8fdb\u884c\u4e86constructor.setAccesssible(true)\u7684\u64cd\u4f5c\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u7684\u4f5c\u7528\u662f\u5173\u95ed\u5bf9constructor\u8fd9\u4e2a\u5bf9\u8c61\u8bbf\u95ee\u65f6\u7684Java\u8bed\u8a00\u8bbf\u95ee\u68c0\u67e5\u3002\u8bed\u8a00\u8bbf\u95ee\u68c0\u67e5\u662f\u4e2a\u8017\u65f6\u7684\u64cd\u4f5c\uff0c\u6240\u4ee5\u5408\u7406\u731c\u6d4b\u662f\u4e3a\u4e86\u63d0\u9ad8\u53cd\u5c04\u6027\u80fd\u5173\u95ed\u4e86\u8fd9\u4e2a\u68c0\u67e5\uff0c\u53c8\u51fa\u4e8e\u5b89\u5168\u8003\u8651\uff0c\u6240\u4ee5\u5c06\u6700\u539f\u59cb\u7684\u5bf9\u8c61\u8fdb\u884c\u4e86\u5c01\u88c5\u3002<\/p>\n<pre><code>private Constructor&lt;T&gt; getConstructor0(Class&lt;?&gt;[] parameterTypes,\n                                    int which) throws NoSuchMethodException\n{\n\/\/1\u3001\u62ff\u5230Constructor\u5b9e\u4f8b\u6570\u7ec4\u5e76\u8fdb\u884c\u7b5b\u9009\n    Constructor&lt;T&gt;[] constructors = privateGetDeclaredConstructors((which == Member.PUBLIC));\n \/\/2\u3001\u901a\u8fc7\u5bf9\u5165\u53c2\u7684\u6bd4\u8f83\u7b5b\u9009\u51fa\u7b26\u5408\u6761\u4ef6\u7684Constructor\n    for (Constructor&lt;T&gt; constructor : constructors) {\n        if (arrayContentsEq(parameterTypes,\n                            constructor.getParameterTypes())) {\n\/\/3\u3001\u521b\u5efa\u526f\u672cConstructor\n            return getReflectionFactory().copyConstructor(constructor);\n        }\n    }\n    throw new NoSuchMethodException(getName() + &quot;.&lt;init&gt;&quot; + argumentTypesToString(parameterTypes));\n}<\/code><\/pre>\n<h3>3.2 \u76ee\u6807\u7c7b\u5b9e\u4f8b\u7684\u6784\u9020<\/h3>\n<p>sun.reflect.ConstructorAccessor#newInstance<\/p>\n<p>\u6b64\u65b9\u6cd5\u4e3b\u8981\u662f\u5229\u7528\u4e0a\u4e00\u6b65\u521b\u5efa\u51fa\u6765\u7684Constructor\u5bf9\u8c61\uff0c\u8fdb\u884c\u76ee\u6807\u7c7b\u5b9e\u4f8b\u7684\u6784\u9020\u3002Java\u4e3a\u4e86\u63d0\u9ad8\u53cd\u5c04\u7684\u6027\u80fd\uff0c\u4e3a\u7c7b\u5b9e\u4f8b\u7684\u6784\u9020\u63d0\u4f9b\u4e86\u4e24\u79cd\u65b9\u6848\uff0c\u4e00\u79cd\u662f\u865a\u62df\u673a\u81ea\u5df1\u5b9e\u73b0\u7684native\u65b9\u6cd5\uff0c\u4e00\u79cd\u662fJDK\u5305\u91cc\u7684Java\u65b9\u6cd5\u3002<\/p>\n<p>\u9996\u5148\u6765\u770b\u4ee3\u7801\u91cc\u5bf9ConstructorAccessor\u5bf9\u8c61\u7684\u6784\u9020\uff0c\u901a\u8fc7\u4ee3\u7801\u53ef\u4ee5\u770b\u51fa\u5728\u65b9\u6cd5newConstructorAccessor\u4e2d\u6784\u9020\u4e86ConstructorAccessor\u63a5\u53e3\u7684\u4e24\u4e2a\u5b9e\u73b0\u7c7b\uff0c\u4e24\u4e2a\u5bf9\u8c61\u8fdb\u884c\u4e86\u76f8\u4e92\u5f15\u7528\uff0c\u50cf\u8fd9\u6837\u5b50\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043948626\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<pre><code>\/\/\u6784\u9020ConstructorAccessor\u5bf9\u8c61\npublic ConstructorAccessor newConstructorAccessor(Constructor&lt;?&gt; var1) {\n        if (Modifier.isAbstract(var2.getModifiers())) {\n      ......\n        } else {\n            NativeConstructorAccessorImpl var3 = new NativeConstructorAccessorImpl(var1);\n            DelegatingConstructorAccessorImpl var4 = new DelegatingConstructorAccessorImpl(var3);\n            var3.setParent(var4);\n            return var4;\n        }\n    }<\/code><\/pre>\n<p>\u5728\u8c03\u7528DelegatingConstructorAccessorImpl\u7684newInstance\u65b9\u6cd5\u65f6\uff0c\u76f8\u5f53\u4e8e\u4e3aNativeConstructorAccessorImpl\u505a\u4e86\u4e00\u5c42\u4ee3\u7406\uff0c\u5b9e\u9645\u8c03\u7528\u7684\u662fNativeConstructorAccessorImpl\u7c7b\u5b9e\u73b0\u7684\u65b9\u6cd5\u3002<\/p>\n<pre><code> public Object newInstance(Object[] var1) throws InstantiationException, IllegalArgumentException, InvocationTargetException {\n        return this.delegate.newInstance(var1);\n    }<\/code><\/pre>\n<p>newInstance\u65b9\u6cd5\u4e2d\u51b3\u5b9a\u4f7f\u7528\u54ea\u79cd\u65b9\u6cd5\u7684\u662f\u4e00\u4e2a\u540d\u4e3anumInvocations\u7684int\u7c7b\u578b\u7684\u53d8\u91cf\uff0c\u6bcf\u6b21\u8c03\u7528\u5230newInstance\u65b9\u6cd5\u65f6\uff0c\u8fd9\u4e2a\u53d8\u91cf\u90fd\u4f1a+1\uff0c\u5f53\u53d8\u91cf\u503c\u8d85\u8fc7\u9608\u503c\uff0815\uff09\u65f6\uff0c\u5c31\u4f1a\u4f7f\u7528Java\u65b9\u5f0f\u8fdb\u884c\u76ee\u6807\u7c7b\u5b9e\u4f8b\u7684\u521b\u9020\uff0c\u53cd\u4e4b\u5c31\u4f1a\u4f7f\u7528\u865a\u62df\u673a\u5b9e\u73b0\u7684\u65b9\u5f0f\u8fdb\u884c\u76ee\u6807\u7c7b\u5b9e\u4f8b\u7684\u521b\u9020\u3002  <\/p>\n<p>\u8fd9\u6837\u505a\u662f\u56e0\u4e3aJava\u7248\u672c\u7684\u5b9e\u73b0\u6d41\u7a0b\u5f88\u957f\uff0c\u5176\u4e2d\u8fd8\u5305\u542b\u4e86\u5b57\u8282\u7801\u6784\u9020\u7684\u6d41\u7a0b\uff0c\u6240\u4ee5\u521d\u6b21\u6784\u9020\u6bd4\u8f83\u8017\u65f6\uff0c\u4f46\u662f\u957f\u4e45\u6765\u8bf4\u6027\u80fd\u66f4\u597d\uff0c\u800cnative\u7248\u672c\u662f\u521d\u671f\u4f7f\u7528\u901f\u5ea6\u8f83\u5757\uff0c\u8c03\u7528\u9891\u7e41\u7684\u8bdd\u6027\u80fd\u4f1a\u6709\u6240\u4e0b\u964d\uff0c\u6240\u4ee5\u505a\u4e86\u6839\u636e\u9608\u503c\u6765\u5224\u65ad\u4f7f\u7528\u54ea\u4e2a\u7248\u672c\u7684\u8bbe\u8ba1\u3002<\/p>\n<pre><code>    public Object newInstance(Object[] var1) throws InstantiationException, IllegalArgumentException, InvocationTargetException {\n        if (++this.numInvocations &gt; ReflectionFactory.inflationThreshold() &amp;&amp; !ReflectUtil.isVMAnonymousClass(this.c.getDeclaringClass())) {\n\/\/Java\u65b9\u6cd5\u6784\u9020\u5bf9\u8c61\n            ConstructorAccessorImpl var2 = (ConstructorAccessorImpl)(new MethodAccessorGenerator()).generateConstructor(this.c.getDeclaringClass(), this.c.getParameterTypes(), this.c.getExceptionTypes(), this.c.getModifiers());\n            this.parent.setDelegate(var2);\n        }\n\/\/native\u65b9\u6cd5\u5b9e\u73b0\u5b9e\u4f8b\u5316\n        return newInstance0(this.c, var1);\n    }<\/code><\/pre>\n<p>\u91cd\u70b9\u5173\u6ce8\u4ee5\u4e0bJava\u7248\u672c\u7684\u5b9e\u73b0\u6d41\u7a0b\uff0c\u9996\u5148\u6784\u9020\u4e86\u4e00\u4e2aConstructorAccessorImpl\u7c7b\u7684\u5bf9\u8c61\u3002\u8fd9\u4e2a\u5bf9\u8c61\u7684\u6784\u9020\u4e3b\u8981\u662f\u4f9d\u9760\u5728\u4ee3\u7801\u91cc\u6309\u7167\u5b57\u8282\u7801\u6587\u4ef6\u7684\u683c\u5f0f\u6784\u9020\u51fa\u6765\u4e00\u4e2a\u5b57\u8282\u6570\u7ec4\u5b9e\u73b0\u7684\u3002\u9996\u5148\u521b\u5efa\u4e86\u4e00\u4e2aByteVactor\u63a5\u53e3\u7684\u5b9e\u73b0\u7c7b\u5bf9\u8c61\uff0c\u6b64\u7c7b\u6709\u4e24\u4e2a\u5c5e\u6027\uff0c\u4e00\u4e2a\u5b57\u8282\u6570\u7ec4\uff0c\u4e00\u4e2aint\u7c7b\u578b\u7684\u6570\u7528\u6765\u6807\u8bc6\u4f4d\u7f6e\u3002ClassFileAssembler\u7c7b\u4e3b\u8981\u8d1f\u8d23\u628a\u5404\u7c7b\u503c\u8f6c\u5316\u6210\u5b57\u8282\u7801\u7684\u683c\u5f0f\u7136\u540e\u586b\u5145\u5230ByteVactor\u7684\u5b9e\u73b0\u7c7b\u5bf9\u8c61\u91cc\u3002\u6700\u540e\u7531ClassDefiner.defineClass\u65b9\u6cd5\u5bf9\u5b57\u8282\u7801\u6570\u7ec4\u8fdb\u884c\u5904\u7406\uff0c\u6784\u9020\u51faConstructorAccessorImpl\u5bf9\u8c61\u3002 \u6700\u540eConstructorAccessorImpl\u5b9e\u4f8b\u8fd8\u662f\u4f1a\u88ab\u4f20\u7ed9newInstance0()\u8fd9\u4e2anative\u65b9\u6cd5\uff0c\u4ee5\u6b64\u6765\u6784\u9020\u6700\u7ec8\u7684\u76ee\u6807\u7c7b\u5b9e\u4f8b<\/p>\n<pre><code>private MagicAccessorImpl generate(final Class&lt;?&gt; var1, String var2, Class&lt;?&gt;[] var3, Class&lt;?&gt; var4, Class&lt;?&gt;[] var5, int var6, boolean var7, boolean var8, Class&lt;?&gt; var9) {\n \/\/\u521b\u5efaByteVectorImpl\u5bf9\u8c61\n ByteVector var10 = ByteVectorFactory.create();\n \/\/\u521b\u5efaClassFileAssembler\u5bf9\u8c61\n    this.asm = new ClassFileAssembler(var10);\n......\n        var10.trim();\n\/\/\u62ff\u51fa\u6784\u9020\u597d\u7684\u5b57\u8282\u6570\u7ec4\uff08\u5c31\u662f\u5b57\u8282\u7801\u6587\u4ef6\u7684\u683c\u5f0f\uff09\n        final byte[] var17 = var10.getData();\n        return (MagicAccessorImpl)AccessController.doPrivileged(new PrivilegedAction&lt;MagicAccessorImpl&gt;() {\n            public MagicAccessorImpl run() {\n                try {\n\/\/\u8c03\u7528native\u65b9\u6cd5\uff0c\u521b\u5efaConstructorAccessorImpl\u7c7b\u7684\u5b9e\u4f8b\n\/\/\u6700\u540eConstructorAccessorImpl\u5b9e\u4f8b\u8fd8\u662f\u4f1a\u88ab\u4f20\u7ed9newInstance0()\u8fd9\u4e2anative\u65b9\u6cd5\uff0c\u4ee5\u6b64\u6765\u6784\u9020\u6700\u7ec8\u7684\u76ee\u6807\u7c7b\u5b9e\u4f8b\n                    return (MagicAccessorImpl)ClassDefiner.defineClass(var13, var17, 0, var17.length, var1.getClassLoader()).newInstance();\n                } catch (IllegalAccessException | InstantiationException var2) {\n                    throw new InternalError(var2);\n                }\n            }\n        });\n    }\n}<\/code><\/pre>\n<h2>4 \u5c0f\u7ed3<\/h2>\n<p>\u6700\u540e\u6839\u636e\u4e0a\u8ff0\u5b66\u4e60\u601d\u8003\u4e0bJava\u53cd\u5c04\u5230\u5e95\u6162\u4e0d\u6162\u8fd9\u4e2a\u95ee\u9898\u3002\u9996\u5148\u53ef\u4ee5\u770b\u5230JDK\u4e3a\u201c\u53cd\u5c04\u65f6\u521b\u5efa\u5bf9\u8c61\u7684\u8fc7\u7a0b\u201d\u63d0\u4f9b\u4e86\u4e24\u5957\u5b9e\u73b0\uff0cnative\u7248\u672c\u66f4\u5feb\u4f46\u662f\u4e5f\u4f7f\u5f97JVM\u65e0\u6cd5\u5bf9\u5176\u8fdb\u884c\u4e00\u4e9b\u4f18\u5316\uff08\u8b6c\u5982JIT\u7684\u65b9\u6cd5\u5185\u8054\uff09\uff0c\u5f53\u65b9\u6cd5\u6210\u4e3a\u70ed\u70b9\u65f6\uff0c\u8f6c\u7528Java\u7248\u672c\u6765\u8fdb\u884c\u5b9e\u73b0\u5219\u4f18\u5316\u4e86\u8fd9\u4e2a\u95ee\u9898\u3002\u4f46Java\u7248\u672c\u7684\u5b9e\u73b0\u8fc7\u7a0b\u4e2d\u9700\u8981\u52a8\u6001\u751f\u6210\u5b57\u8282\u7801\uff0c\u8fd8\u8981\u52a0\u8f7d\u4e00\u4e9b\u989d\u5916\u7684\u7c7b\uff0c\u9020\u6210\u4e86\u5185\u5b58\u7684\u6d88\u8017\uff0c\u6240\u4ee5\u4f7f\u7528\u53cd\u5c04\u7684\u65f6\u5019\u8fd8\u662f\u5e94\u5f53\u6ce8\u610f\u4e00\u4e9b\u662f\u5426\u4f1a\u56e0\u4e3a\u4f7f\u7528\u8fc7\u591a\u800c\u9020\u6210\u5185\u5b58\u6ea2\u51fa\u3002<\/p>\n<p>\u4e00\u6b21\u4e0d\u6210\u719f\u7684\u6e90\u7801\u5b66\u4e60\u5386\u7a0b\uff0c\u5982\u6709\u9519\u8bef\u8fd8\u8bf7\u6307\u6b63\u3002<\/p>\n<p>\u53c2\u8003\u8d44\u6599\uff1a  <br \/><a href=\"https:\/\/link.segmentfault.com\/?enc=sPg%2Fh7VtfNkUwI6BH30lgg%3D%3D.7junsU%2FhQZzfRhCTnSceV7vvcJoqVlTd4ilfdvySTnXjuvbnd3Cs3tJv%2FEavsuhP\" rel=\"nofollow\">https:\/\/rednaxelafx.iteye.com\/blog\/548536<\/a><\/p>\n<blockquote>\n<p>\u4f5c\u8005\uff1a\u4eac\u4e1c\u7269\u6d41 \u79e6\u66cc\u6021<\/p>\n<p>\u6765\u6e90\uff1a\u4eac\u4e1c\u4e91\u5f00\u53d1\u8005\u793e\u533a<\/p>\n<\/blockquote>\n<p><a href=\"https:\/\/segmentfault.com\/a\/1190000043948616\">https:\/\/segmentfault.com\/a\/1190000043948616<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>1 \u80cc\u666f \u524d\u6bb5\u65f6\u95f4\u7ec4\u5185\u9488\u5bf9\u201c\u62f7\u8d1d\u5b9e\u4f8b\u5c5e\u6027\u662f\u5e94\u8be5\u7528BeanUtils.copyProperties\uff08\uff09\u8fd8\u662fMap [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10008017","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008017","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10008017"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008017\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10008017"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10008017"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10008017"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}