Class MessageParameterResolver

java.lang.Object
io.fluxzero.sdk.tracking.handling.MessageParameterResolver
All Implemented Interfaces:
HandlerInputResolver<Object>, ParameterResolver<Object>, PreparedParameterResolver<Object>
public class MessageParameterResolver extends Object implements PreparedParameterResolver<Object>, HandlerInputResolver<Object>
Resolves handler method parameters of type DeserializingMessage.

This allows handler methods to access the deserialization context, including message metadata, payload, and raw serialized content.

Useful when advanced information about the message is needed, such as the Fluxzero-assigned message index.

  • Constructor Details

    • MessageParameterResolver

      public MessageParameterResolver()

  • Method Details

    • resolve

      public Function<Object,Object> resolve(Parameter p, Annotation methodAnnotation)
      Description copied from interface: ParameterResolver
      Resolves a Parameter of a handler method into a value function based on the given message.

      If the parameter cannot be resolved by this resolver and ParameterResolver.matches(Parameter, Annotation, M) is not implemented, this method must return null.

      Specified by:
      resolve in interface ParameterResolver<Object>
      Parameters:
      p - the parameter to resolve
      methodAnnotation - the annotation present on the handler method (e.g., @HandleEvent)
      Returns:
      a function that takes a message and returns a value to be injected into the method parameter, or null if the parameter cannot be resolved and ParameterResolver.matches(Parameter, Annotation, M) is not implemented.

    • prepare

      public Function<Object,Object> prepare(Parameter parameter, Annotation methodAnnotation)
      Description copied from interface: ParameterResolver
      Prepares a resolver function when this resolver can determine compatibility from the parameter and method annotation alone.

      The default returns null, which keeps resolution message-dependent. Implementations should override this only when ParameterResolver.matches(Parameter, Annotation, Object) would always be true for the supplied parameter, regardless of the message instance. Dynamic resolvers such as payload, trigger, or entity resolvers should keep the default behavior.

      Specified by:
      prepare in interface ParameterResolver<Object>
      Parameters:
      parameter - the parameter to resolve
      methodAnnotation - the annotation present on the handler method
      Returns:
      a prepared resolver, or null when resolution must remain message-dependent

    • resolveIfPossible

      public Function<Object,Object> resolveIfPossible(Parameter parameter, Annotation methodAnnotation, Object value)
      Description copied from interface: PreparedParameterResolver
      Returns a prepared resolver for the given message, or null when this resolver cannot handle the parameter.
      Specified by:
      resolveIfPossible in interface PreparedParameterResolver<Object>

    • matches

      public boolean matches(Parameter parameter, Annotation methodAnnotation, Object value)
      Description copied from interface: ParameterResolver
      Indicates whether the resolved value is compatible with the declared parameter type.

      This method helps determine whether the parameter can be injected for a given message. It first invokes ParameterResolver.resolve(Parameter, Annotation) and then verifies that the returned value (if any) is assignable to the parameter type.

      Specified by:
      matches in interface ParameterResolver<Object>
      Parameters:
      parameter - the parameter being checked
      methodAnnotation - the annotation on the handler method
      value - the message instance to use for resolution
      Returns:
      true if the parameter can be resolved and assigned to, false otherwise

    • mayApply

      public boolean mayApply(Executable method, Class<?> targetClass)
      Description copied from interface: ParameterResolver
      Returns true if this resolver might apply to the given method. Implementations should perform only inexpensive checks and never throw.
      Specified by:
      mayApply in interface ParameterResolver<Object>
      Parameters:
      method - the handler method or constructor
      targetClass - the declaring or target class
      Returns:
      true if this resolver could apply, false otherwise

    • getInputCacheKey

      public Object getInputCacheKey(Parameter parameter, Annotation methodAnnotation, HandlerInput<Object> representative)
      Description copied from interface: HandlerInputResolver
      Returns a key containing every input property that can affect whether this resolver matches the parameter and how the parameter value is resolved.

      Return null when no safe reusable key can be provided. Fluxzero will then fall back to normal per-message resolution. Keys are compared using Object.equals(Object) and must be stable after they are returned.

      Specified by:
      getInputCacheKey in interface HandlerInputResolver<Object>
      Parameters:
      parameter - the handler parameter to resolve
      methodAnnotation - the annotation that marks the handler method, if present
      representative - an input representative of the group to be cached
      Returns:
      a stable, complete cache key, or null to disable prepared resolution for this input

    • isPayloadClassKey

      public boolean isPayloadClassKey(Parameter parameter, Annotation methodAnnotation, HandlerInput<Object> representative)
      Description copied from interface: HandlerInputResolver
      Returns whether the payload's runtime class alone determines this resolver's successful result for the supplied parameter.

      Return true only if every payload of that class produces the same match decision and may use the same prepared resolver. This enables a faster class-based lookup.

      Specified by:
      isPayloadClassKey in interface HandlerInputResolver<Object>
      Returns:
      true if the result can safely be reused for every payload of the same runtime class

    • isNoMatchPayloadClassKey

      public boolean isNoMatchPayloadClassKey(Parameter parameter, Annotation methodAnnotation, HandlerInput<Object> representative)
      Description copied from interface: HandlerInputResolver
      Returns whether an unmatched result is guaranteed to remain unmatched for every payload with the same runtime class.

      This is separate from HandlerInputResolver.isPayloadClassKey(Parameter, Annotation, HandlerInput) because matching and non-matching inputs may require different cache guarantees.

      Specified by:
      isNoMatchPayloadClassKey in interface HandlerInputResolver<Object>
      Returns:
      true if the non-match can safely be reused for the entire payload class

    • prepareInput

      public HandlerInputResolver.Resolution<Object> prepareInput(Parameter parameter, Annotation methodAnnotation, HandlerInput<Object> representative)
      Description copied from interface: HandlerInputResolver
      Determines whether this resolver handles the parameter and, when it does, creates the function that supplies the parameter value during invocation.

      The result must agree with normal ParameterResolver selection, including any contribution the resolver makes to handler specificity.

      Specified by:
      prepareInput in interface HandlerInputResolver<Object>
      Parameters:
      parameter - the handler parameter to resolve
      methodAnnotation - the annotation that marks the handler method, if present
      representative - an input representative of the cache key returned for this parameter
      Returns:
      an unmatched, rejected, or successfully resolved result