Java的动态代理如何实际工作？

Question

I understand how to use Dynamic Proxies in Java but what I don't understand is how the VM actually creates a dynamic proxy. Does it generate bytecode and load it? Or something else? Thanks.

Answer 1

至少对于Sun的实现，如果你看一下java.lang.reflect.Proxy的源代码，你会看到是的，它会动态生成字节代码（使用类sun.misc.ProxyGenerator ）。

Answer 2

I suggest that you read Dynamic Proxy Classes :

The Proxy.getProxyClass method returns the java.lang.Class object for a proxy class given a class loader and an array of interfaces. The proxy class will be defined in the specified class loader and will implement all of the supplied interfaces. If a proxy class for the same permutation of interfaces has already been defined in the class loader, then the existing proxy class will be returned; otherwise, a proxy class for those interfaces will be generated dynamically and defined in the class loader. [emphasis mine]

Answer 3

The proxy class is generated on-the fly (hence dynamic proxy) and loaded by the classloader. That's why if you debug applications that relies on JDK proxying you'll see bunch of classes named ' com.sun.proxy.$Proxy0 '.

To test my theory you can use an example from Dynamic proxy classes along with the VM parameter which will tell you the loaded classes by the classloader and you shall notice among the classes loaded the .