將參數傳遞給bytebuddy攔截器

Question

我有一個使用Byte Buddy的攔截器，並且想將參數傳遞給攔截器。 我怎樣才能做到這一點？

ExpressionHandler expressionHandler = ... // a handler 
Method method = ... // the method that will be intercepted
ByteBuddy bb = new ByteBuddy();
bb.subclass(theClazz)
   .method(ElementMatchers.is(method))
   .intercept(MethodDelegation.to(MethodInterceptor.class));
   .make()
   .load(theClazz.getClassLoader(), ClassLoadingStrategy.Default.WRAPPER);

MethodInterceptor的攔截方法為：

@RuntimeType
public static Attribute intercept(@Origin Method method, @AllArguments Object[] args) throws Exception {       
    String name = method.getName();
    Class<? extends Attribute> type = (Class<? extends Attribute>) method.getReturnType();
    ExpressionHandler expressionHandler= // ??? 
    expressionHandler.attachStuff(name, type);
    return expressionHandler;
}

如何將expressionHandler從構建器傳遞到攔截器方法？

Answer 1

只需使用實例委托而不是類級委托即可：

MethodDelegation.to(new MethodInterceptor(expressionHandler))

與

public class MethodInterceptor {

  private final ExpressionHandler expressionHandler;

  public MethodInterceptor(ExpressionHandler expressionHandler) {
    this.expressionHandler = expressionHandler;
  }

  @RuntimeType
  public Attribute intercept(@Origin Method method, @AllArguments Object[] args) throws Exception {       
    String name = method.getName();
    Class<? extends Attribute> type = (Class<? extends Attribute>) method.getReturnType();
    this.expressionHandler.attachStuff(name, type);
    return expressionHandler;
  }
}