Package org.springframework.messaging.handler.annotation.reactive

Class AbstractNamedValueMethodArgumentResolver

java.lang.Object
org.springframework.messaging.handler.annotation.reactive.AbstractNamedValueMethodArgumentResolver
All Implemented Interfaces:
HandlerMethodArgumentResolver, SyncHandlerMethodArgumentResolver
Direct Known Subclasses:
DestinationVariableMethodArgumentResolver, HeaderMethodArgumentResolver
public abstract class AbstractNamedValueMethodArgumentResolver extends Object implements SyncHandlerMethodArgumentResolver
Abstract base class to resolve method arguments from a named value, e.g. message headers or destination variables. Named values could have one or more of a name, a required flag, and a default value.

Subclasses only need to define specific steps such as how to obtain named value details from a method parameter, how to resolve to argument values, or how to handle missing values.

A default value string can contain ${...} placeholders and Spring Expression Language #{...} expressions which will be resolved if a ConfigurableBeanFactory is supplied to the class constructor.

A ConversionService is used to convert a resolved String argument value to the expected target method parameter type.

Since:
5.2
Author:
Rossen Stoyanchev

  • Constructor Details

    • AbstractNamedValueMethodArgumentResolver

      protected AbstractNamedValueMethodArgumentResolver(org.springframework.core.convert.ConversionService conversionService, @Nullable org.springframework.beans.factory.config.ConfigurableBeanFactory beanFactory)
      Constructor with a ConversionService and a BeanFactory.
      Parameters:
      conversionService - conversion service for converting String values to the target method parameter type
      beanFactory - a bean factory for resolving ${...} placeholders and #{...} SpEL expressions in default values

  • Method Details

    • resolveArgumentValue

      @Nullable public Object resolveArgumentValue(org.springframework.core.MethodParameter parameter, Message<?> message)
      Description copied from interface: SyncHandlerMethodArgumentResolver
      Resolve the value for the method parameter synchronously.
      Specified by:
      resolveArgumentValue in interface SyncHandlerMethodArgumentResolver
      Parameters:
      parameter - the method parameter
      message - the currently processed message
      Returns:
      the resolved value, if any

    • createNamedValueInfo

      protected abstract AbstractNamedValueMethodArgumentResolver.NamedValueInfo createNamedValueInfo(org.springframework.core.MethodParameter parameter)
      Create the AbstractNamedValueMethodArgumentResolver.NamedValueInfo object for the given method parameter. Implementations typically retrieve the method annotation by means of MethodParameter.getParameterAnnotation(Class).
      Parameters:
      parameter - the method parameter
      Returns:
      the named value information

    • resolveArgumentInternal

      @Nullable protected abstract Object resolveArgumentInternal(org.springframework.core.MethodParameter parameter, Message<?> message, String name)
      Resolves the given parameter type and value name into an argument value.
      Parameters:
      parameter - the method parameter to resolve to an argument value
      message - the current request
      name - the name of the value being resolved
      Returns:
      the resolved argument. May be null

    • handleMissingValue

      protected abstract void handleMissingValue(String name, org.springframework.core.MethodParameter parameter, Message<?> message)
      Invoked when a value is required, but resolveArgumentInternal(org.springframework.core.MethodParameter, org.springframework.messaging.Message<?>, java.lang.String) returned null and there is no default value. Subclasses can throw an appropriate exception for this case.
      Parameters:
      name - the name for the value
      parameter - the target method parameter
      message - the message being processed