如何通过电线发送课程 [英] How to send a Class over the wire

问题描述

我有以下问题：我想通过线路发送一个类型（java.lang.Class）并在另一侧'定义'该类。

I have the following problem: I want to send a type (java.lang.Class) over the wire and 'define' the class on the other side.

我试过这样：

ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bos);
oos.writeObject(MyClass.class);

和接收端：

ByteArrayInputStream bis = new ByteArrayInputStream(request.getBytes());
ObjectInputStream ois = new ObjectInputStream(bis);
Class c = (Class) ois.readObject(); // ClassNotFoundException

所以显然我需要发送类的原始字节码并做一个

so obviously I need to send the raw bytecode of the class and do a

ClassLoader.defineClass(bytes, ..

但不幸的是我没有看到如何检索已加载类的字节码。
我正在搜索类似的内容：

but unfortunately I fail to see how I can retrieve the bytcode of a loaded class. I'm searching for something like:

byte[] byteCode = MyClass.class.toByteArray();

这是否可以使用标准JDK或者是否有任何小型lib可以做到这一点？

Is this even possible with standard JDK or is there any small lib out there that can do that?

推荐答案

我不喜欢我认为你想要的东西是完全通用的。从字节码中定义一个类的行为是不可逆的。但你应该做的是直接读取字节码文件（假设它是 URLClassLoader ）：

I don't think what you want is possible in full generality. The act of defining a class from its bytecode is not reversible. What you should be able to do, however, is to directly read the bytecode file (assuming that it's an URLClassLoader):

MyClass.class.getResourceAsStream("Myclass.class")

或者，你可以通过HTTP访问类文件，并在接收方直接使用 URLClassLoader 。

Alternatively, you could just make the class files accessible via HTTP and directly use an URLClassLoader on the receiving side.

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