java如何在第一个MethodCall的第一个参数上使用另一个MethodCall调用MethodCall？

1 年，5 月 Questions & Answers 140

我正试图实现这一点：

@Override // java.util.Function
public Object apply(final ThingWithParameters thing) {
  return bozo(thing.getParameters());
}
private Object bozo(final Object[] parameters) {
  // Use magic ByteBuddy stuff to "spread" the parameters out
  return this.object.baz(parameter0, parameter1); // ...where these are the first two parameters in the array
}

我试过：

builder = builder
  .defineMethod("bozo" ...)
  .implement(MethodCall.invoke(bazDescription)
             .onField(thisObjectFieldDescription)
             .withArgumentArrayElements(0, 2))

  .implement(parameterizedTypeFunctionThingWithParametersObject) // Function<ThingWithParameters, Object>
  .intercept(MethodCall.invoke(bozoDescription) // implement apply(ThingWithParameters thing): call bozo()...
             .withMethodCall(MethodCall.invoke(getParametersMethodDescription) // ...with the result of invoking getParameters()...
                             .onArgument(0))); // ...on thing (except see below)

…但这不起作用。这个错误消息非常奇怪，让我相信参数0不是指thing，而是指完全其他的东西（可能是某种接收器类型？）。以下是堆栈中的一个片段：

java.lang.IllegalStateException: Cannot invoke public java.lang.Object[] com.foo.ThingWithParameters.getParameters() on java.util.function.Function<? super V, ? extends com.foo.ThingWithParameters>
    at net.bytebuddy.implementation.MethodCall$TargetHandler$ForMethodParameter$Resolved.toStackManipulation(MethodCall.java:2530)
    at net.bytebuddy.implementation.MethodCall$Appender.toStackManipulation(MethodCall.java:3548)
    at net.bytebuddy.implementation.MethodCall$ArgumentLoader$ForMethodCall.toStackManipulation(MethodCall.java:1687)
    at net.bytebuddy.implementation.MethodCall$Appender.toStackManipulation(MethodCall.java:3545)
    at net.bytebuddy.implementation.MethodCall$Appender.apply(MethodCall.java:3509)
    at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod$WithBody.applyCode(TypeWriter.java:708)
    at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod$WithBody.applyBody(TypeWriter.java:693)
    at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod.apply(TypeWriter.java:600)
    at net.bytebuddy.dynamic.scaffold.TypeWriter$Default$ForCreation.create(TypeWriter.java:5660)
    at net.bytebuddy.dynamic.scaffold.TypeWriter$Default.make(TypeWriter.java:2166)
    at net.bytebuddy.dynamic.scaffold.subclass.SubclassDynamicTypeBuilder.make(SubclassDynamicTypeBuilder.java:232)

注意，虽然我的代理类实际上实现了Function，但它实际上实现了Function<ThingWithParameters, Object>。而且，我从不定义V。我假设ByteBuddy在内部某个地方这样做

我应该用什么配方

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java如何在第一个MethodCall的第一个参数上使用另一个MethodCall调用MethodCall？

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