Byte Buddy 中的拦截器类可见性

Question

即使我提供了实际实例，Byte Buddy 似乎也只将公共类视为拦截器实现；我经常发现自己想做这样的事情：

import static MethodDelegation.to;

new ByteBuddy().subclass(Object.class).method(any()).intercept(to(new Object() {
  @RuntimeType
  public Object intercept(@Origin Method m, @AllArguments Object[] a) {
    return null;
  }
});

然而，这会导致如下异常：

Exception in thread "main" java.lang.IllegalStateException: class net.bytebuddy.renamed.java.lang.Object$ByteBuddy$pUmdGhyP cannot access class us.levk.guice.vs.Scopes$1Builder$1

可见性强制执行背后是否有任何原因？

编辑：虽然我仍然遇到问题；我得到了一个不同的例外，这是我的代码：

package us.levk.guice.vs;

import static net.bytebuddy.implementation.MethodDelegation.to;
import static net.bytebuddy.matcher.ElementMatchers.any;

import java.lang.reflect.Method;
import java.util.function.Function;
import java.util.function.Supplier;

import net.bytebuddy.ByteBuddy;
import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
import net.bytebuddy.implementation.bind.annotation.AllArguments;
import net.bytebuddy.implementation.bind.annotation.Origin;
import net.bytebuddy.implementation.bind.annotation.RuntimeType;

public class Bar {

  Function<Supplier<?>, Class<?>> wrapper () {
    return s -> {
      return new ByteBuddy ().subclass (Object.class)
                             .name (Bar.class.getPackage ().getName () + ".Foo")
                             .method (any ())
                             .intercept (to (new Object () {
                               @RuntimeType
                               public Object intercept (@Origin Method method,
                                                        @AllArguments Object[] args) {
                                 System.out.println (method);
                                 return null;
                               }
                             }))
                             .make ()
                             .load (getClass ().getClassLoader (),
                                    ClassLoadingStrategy.Default.WRAPPER)
                             .getLoaded ();
    };
  }

  public static void main (String[] args) throws InstantiationException, IllegalAccessException {
    new Bar ().wrapper ().apply ( () -> new Integer (1)).newInstance ().toString ();
  }
}

现在的例外是：

Exception in thread "main" java.lang.IllegalAccessError: tried to access class us.levk.guice.vs.Bar$1 from class us.levk.guice.vs.Foo

编辑2：

如果我将类加载策略更改为 INJECTION，它工作正常

Answer 1

IllegalAccessException在这种情况下，Byte Buddy 会通知您可能在运行时导致的可见性约束。

即使您声明了您的方法，匿名类也会被javacpublic自动定义为包私有。因此，该方法对于生成的类不可见，因为不等于。net.bytebuddy.renamed.java.lang.Objectus.levk.guice.vs.Scopes

如果你这样做：

new ByteBuddy().subclass(Object.class).name("us.levk.guice.vs.Foo")
               .method(any()).intercept(to(new Object() {
  @RuntimeType
  public Object intercept(@Origin Method m, @AllArguments Object[] a) {
    return null;
  }
}));

一切都会成功。或者，您可以定义 - 例如 - 公共接口，例如：

public interface Foo {
  @RuntimeType
  Object intercept(@Origin Method m, @AllArguments Object[] a);
}

new ByteBuddy().subclass(Object.class).name("us.levk.guice.vs.Foo")
               .method(any()).intercept(to(new Foo() {
  @RuntimeType
  public Object intercept(@Origin Method m, @AllArguments Object[] a) {
    return null;
  }
}, Foo.class));