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JVM上的所有“Magic”方法都标记为Native吗？

[英]Are all the “Magic” methods on the JVM marked as Native?

原文 2012-11-06 05:24:46 5 2 java/ jvm/ java-native-interface/ native/ bytecode

By "Magic" I mean the methods which have semantics which are not expressed in pure Java. “魔术”是指具有语义的方法，这些语法不是用纯Java表达的。

I know all native methods are magic, in that their implementation is provided by the underlying runtime and not by Java bytecodes. 我知道所有native方法都很神奇，因为它们的实现是由底层运行时提供的，而不是由Java字节码提供的。

Is the reverse true? 反之亦然吗？ Are all magic methods native , or are there some magic methods apparently implemented in pure Java, but with some extra help from some JVM-special-casing? 所有魔法方法都是native ，还是有一些神奇的方法显然是用纯Java实现的，但是有一些JVM特殊外壳的额外帮助？

The use case is that I want to modify the semantics of Java by instrumenting its bytecodes. 用例是我想通过检测其字节码来修改Java的语义。 All these magic methods are special cases which I will have to handle some way or another. 所有这些神奇的方法都是特殊情况，我将不得不以某种方式处理。 The native ones are all obvious, but I was wondering if there are any unmarked magic methods I have to watch out and special case for. native的都很明显，但我想知道是否有任何无标记的魔术方法我需要注意和特殊情况。

2 个解决方案

Unfortunately there are "magic" methods outside of native methods. 不幸的是，在本机方法之外存在“神奇”方法。 Take a look at intrinsic methods - these methods are known to the JIT, which uses hand rolled implementations when a method is compiled, and include heavily called methods such as String.indexOf, Integer.numberOfLeadingZeros , etc. 看看内部方法 - 这些方法是JIT已知的，它在编译方法时使用手动实现，并包括大量调用的方法，如String.indexOf， Integer.numberOfLeadingZeros等。

Take a look at here , under Intrinsics, for some details and how to determine which methods are intrinsified on your JVM. 在Intrinsics下查看这里的一些细节以及如何确定哪些方法在JVM上进行了内部化。 I'm not sure if injecting bytecode will turn off intrisification, but there is a DisableIntrinsic XX option you can use to disable selected intrinsics. 我不确定注入字节码是否会关闭内部化，但是有一个DisableIntrinsic XX选项可用于禁用选定的内在函数。

You may find that a lot of details have already been handled in AspectJ . 您可能会发现AspectJ已经处理了很多细节。 I would take a look at it before doing manual bytecode manipulation. 在进行手动字节码操作之前，我会先看看它。