BCEL==monkeypatching 用于 java 吗？
有一天，一位同事向我指出了BCEL，我可以从他的解释和快速读取，一种在运行时修改字节码的方法。 我的第一个想法是这听起来很危险，第二个想法是这听起来很酷。 然后我又想了想，我想起了关于猴子修补的codinghorror帖子并意识到这基本上是同一件事。 有人用过 BCEL 做过任何实际的事情吗？ 我是否正确，这基本上是运行时猴子修补，还是我错过了一些东西？
a colleague pointed me the other day to BCEL which , as best I can tell from his explanation and a quick read, a way to modify at run time the byte code. My first thought was that it sounded dangerous, and my second thought was that it sounded cool. Then I gave it some more thought and I recalled the codinghorror post on monkey-patching and realized that this was basically the same thing. Has anyone ever used BCEL for anything practical? Am I right that this is basically run time monkey patching, or am I missing something?
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BCEL 不支持猴子修补，它只是使用字节码进行操作，并可能将其加载到自定义类加载器中。 但是，您可以使用 BCEL 和 Java 代理等库在 JVM 上实现猴子补丁。 Java 代理（由 -javaagent 参数加载）可以访问 Instrumentation API 并修改加载的类。 通过一些桥梁来实现它并不难。
但请记住：
BCEL does not support monkey patching, it just manipulates with bytecode and possibly loads it in a custom classloader. However you can implement monkeypatching on JVM using library like BCEL and Java agent. The Java agent (loaded by -javaagent argument) can access the Instrumentation API and modify loaded classes. It is not hard to implement it via some bridges.
But remember:
它比经典的猴子修补要低一些，根据我的阅读，已经加载到虚拟机中的类不会更新。 它只支持再次保存到类文件中，不支持修改运行时类。
It's a bit more low-level than classic monkey patching, and from what I read, the classes already loaded into the VM are not updated. It only supports saving it to class files again, not modifying run time classes.
您可能会将其视为猴子修补。 我宁愿不使用它（也许我从来没有遇到过它的良好用例？），但要熟悉它（了解 Spring 和 Hibenrate 如何使用它以及为什么）。
You might look at it as monkey patching. I prefer not to use it (maybe I never faced a good use case for it?), but be familiar with it (to have an idea how Spring and Hibenrate use it and why).
请参阅这个现实世界的示例：Jawk - 编译器模块。 BCEL 对于“编译”您的自定义语言很有用。
See this realworld example: Jawk - Compiler Module. BCEL is useful for "compilation" ur custom language.
来自 BCEL 的常见问题解答：
但是monkeypatching是......呃......有争议的，如果你的语言不支持它，你可能不应该使用它。
如果您有一个好的用例，我可以建议嵌入 Jython 吗？
From BCEL's FAQ:
But monkeypatching is... uhm... controversial, and you probably shouldn't use it if your language doesn't support it.
If you have a good use case for it, may I suggest embbededing Jython?