Annotation Interface Advice.FieldValue

Enclosing class:
Advice

@Documented @Retention(RUNTIME) @Target(PARAMETER) public static @interface Advice.FieldValue

Indicates that the annotated parameter should be mapped to a field in the scope of the instrumented method.

Setting value() is optional. If the value is not set, the field value attempts to bind a setter's or getter's field if the intercepted method is an accessor method. Otherwise, the binding renders the target method to be an illegal candidate for binding.

Important: Parameters with this option must not be used when from a constructor in combination with Advice.OnMethodEnter and a non-static field where the this reference is not available.

Note: As the mapping is virtual, Byte Buddy might be required to reserve more space on the operand stack than the optimal value when accessing this parameter. This does not normally matter as the additional space requirement is minimal. However, if the runtime performance of class creation is secondary, one can require ASM to recompute the optimal frames by setting ClassWriter.COMPUTE_MAXS. This is however only relevant when writing to a non-static field.

Important: Don't confuse this annotation with FieldValue annotation. This annotation should be used only in combination with Advice ASM visitor. For method delegation (MethodDelegation.to(...)) use alternative annotation from net.bytebuddy.implementation.bind package.

See Also:
  • Optional Element Summary

    Optional Elements
    Modifier and Type
    Optional Element
    Description
    Returns the type that declares the field that should be mapped to the annotated parameter.
    boolean
    Indicates if it is possible to write to this parameter.
    The typing that should be applied when assigning the field value.
    Returns the name of the field.
  • Element Details

    • value

      String value
      Returns the name of the field.
      Returns:
      The name of the field.
      Default:
      ""
    • declaringType

      Class<?> declaringType
      Returns the type that declares the field that should be mapped to the annotated parameter. If this property is set to void, the field is looked up implicitly within the instrumented class's class hierarchy. The value can also be set to TargetType in order to look up the type on the instrumented type.
      Returns:
      The type that declares the field, void if this type should be determined implicitly or TargetType for the instrumented type.
      Default:
      void.class
    • readOnly

      boolean readOnly

      Indicates if it is possible to write to this parameter. If this property is set to false, the annotated type must be equal to the type declaring the instrumented method if the typing is not also set to Assigner.Typing.DYNAMIC. If this property is set to true, the annotated parameter can be any super type of the instrumented method's declaring type.

      Important: This property must be set to true if the advice method is not inlined.

      Returns:
      true if this parameter is read-only.
      Default:
      true
    • typing

      The typing that should be applied when assigning the field value.
      Returns:
      The typing to apply upon assignment.
      Default:
      STATIC