AnonymousClassLoader位置咨询：OpenJDK8中无法定位该类的问题

Hey there, let's break down why you can't find AnonymousClassLoader in your OpenJDK 8 environment, and what you can use instead.

First: Why the class doesn't exist in OpenJDK 8 #

The AnonymousClassLoader you're looking for (whether under sun.dyn.anon or java.dyn.anon) was never part of the public, stable API in any official JDK 8 release. It started as an experimental component in early prototypes for JVM dynamic language support (like the Da Vinci Machine project), but by the time JDK 8 launched, this class was either removed entirely or its functionality was absorbed into other existing mechanisms.

OpenJDK 8's official dynamic language support focuses on invokedynamic, MethodHandle, CallSite, and related public APIs—there's no formal AnonymousClassLoader provided for general use.

Alternative approaches for dynamic class loading #

If you need to dynamically generate and load classes (which is likely what you wanted AnonymousClassLoader for), you can easily achieve this with a custom subclass of ClassLoader:

public class DynamicClassLoader extends ClassLoader {
    // Load a class from generated bytecode
    public Class<?> loadDynamicClass(String className, byte[] bytecode) {
        return super.defineClass(className, bytecode, 0, bytecode.length);
    }
}

This simple implementation lets you load bytecode (e.g., generated with ASM) directly, just like the hypothetical AnonymousClassLoader would have. For most use cases, this is the recommended approach since it relies on stable, public Java APIs.

A quick note on internal APIs #

Avoid relying on any sun.* or non-public JDK classes—they're not part of the official specification, can change or disappear between releases, and aren't supported by Oracle or the OpenJDK community. Stick to the public java.lang.ClassLoader and related APIs for long-term compatibility.

内容的提问来源于stack exchange，提问作者kiv_apple