ByteBuddy：如何进行方法委托/转发到可变字段

Question

我有这样的（伪代码）：

final Class<OUT> newClass = (Class<OUT>) new ByteBuddy()
.subclass(Object.class)
.name(newName)
.implement(SomeInterface.class, SomeOtherInterface.class)
.method(ElementMatchers.isMethod())                            
.intercept(
    ExceptionMethod.throwing(UnsupportedOperationException.class,
                            "calling this method is not supported"))
// in fact I am matching for more than a single method here
.method(ElementMatchers.named("getUuid"))
.intercept(
    MethodDelegation.toInstanceField(SomeOtherInterface.class, "delegate"))
.make()
.load(aBusinessEntityClass.getClassLoader(), ClassLoadingStrategy.Default.WRAPPER)
.getLoaded();

我当前的问题是：我需要我的 delegate 字段是 volatile。我怎样才能做到这一点？

Answer 1

好的，找到适合我的解决方案，以防有人感兴趣：

final Class<OUT> newClass = (Class<OUT>) new ByteBuddy()
.subclass(Object.class)
.name(newName)
.implement(SomeInterface.class, SomeOtherInterface.class)
.method(ElementMatchers.isMethod())                            
.intercept(
    ExceptionMethod.throwing(UnsupportedOperationException.class,
                        "calling this method is not supported"))
// in fact I am matching for more than a single method here
.method(ElementMatchers.named("getUuid"))
.intercept(
    MethodDelegation.toInstanceField(SomeOtherInterface.class, "delegate"))
// -- HERE THE FIELD IS MODIFIED AGAIN, IN THIS CASE AS  --
// -- PRIVATE & VOLATILE                                 --
.field(ElementMatchers.named("delegate"))                       
.transform(Transformer.ForField.withModifiers(FieldManifestation.VOLATILE, Visibility.PRIVATE))
.make()
.load(aBusinessEntityClass.getClassLoader(), ClassLoadingStrategy.Default.WRAPPER)
.getLoaded();

解决方案是随后通过调用 field() 和 transform() 并适当 Transformer.ForField.withModifiers().

希望对遇到这个问题的大家有所帮助。

Answer 2

toInstanceField API 已随 Byte Buddy 1.5.0 一起退役，取而代之的是新工具 API，您更愿意在其中明确定义字段：

new ByteBuddy()
  .defineField("delegate", SomeOtherInterface.class, VOLATILE)
  .method(ElementMatchers.named("getUuid"))
  .intercept(MethodDelegation.toField("delegate"));

这允许做其他事情，例如添加注释等

此方法现已应用于所有 Implementation。今天发布了新版本

ByteBuddy：如何进行方法委托/转发到可变字段

ByteBuddy: How to do method delegation / forwarding to a volatile field

java

byte-buddy